Compilations and updates on residual feed intake in sheep

The increasing global demand for food and the strong effect of climate change have forced animal science to advance regarding new methods of selection in search of more efficient animals in production systems. Feed consumption represents more than 70% of the costs of sheep farms, and more efficient animals can increase the farmers' profitability. One of the main measures of feed efficiency is estimated residual feed intake (RFI), created in 1963 by Robert Koch for estimation in cattle and later adapted for sheep. Animals with negative RFI values (RFI-) are more efficient than animals with positive values (RFI+), with influence on the variables of performance, carcass quality and production of enteric gases. The RFI is the most common and accepted metric of the feed efficiency trait for genetic selection, since it is independent of growth traits, unlike the feed conversion ratio. The purpose of this review article was to present updated literature information on the relationship of RFI estimates with performance measures, molecular markers, greenhouse gas production and feed efficiency, the technical aspects and physiological basis of metabolic in sheep.

Carcass traits and morphometry, typification of the Longissimus dorsi muscle and non-carcass components of hair lambs: can biscuit bran completely replace corn? A machine learning approach

Biscuit bran (BB) is a co-product with worldwide distribution, with Brazil as the second largest cookie producer in the world with 1,157,051 tons. We evaluate the impact of completely replacing corn with BB on the characteristics and morphometry of carcass of purebred and crossbred Morada Nova lambs using machine learning techniques as an auxiliary method. Twenty male lambs from two genetic groups (GG) were used: purebred red-coated Morada Nova (MNR) and crossbred MNR × white-coated Morada Nova (MNF1). Supervised and unsupervised machine learning techniques were used. No interaction (P > 0.05) was observed between diets (D) and genetic groups (GG) and no simple isolated effect was observed for carcass characteristics, qualitative-quantitative typification of the Longissimus dorsi muscle, weight of non-carcass components, weight and yield of commercial cuts and carcass morphometric measurements. The formation of two horizontal clusters was verified: (i) crossed lambs with corn and BB and (ii) purebred lambs fed corn and BB. Vertically, three clusters were formed based on carcass and meat characteristics of native lambs: (i) thermal insulation, body capacity, true yield, and commercial cuts; (ii) choice, performance, physical carcass traits, and palatability; and (iii) yield cuts and non-carcass components. The heatmap also allowed us to observe that pure MN lambs had a greater body capacity when fed BB, while those fed corn showed superiority in commercial cuts, true yields, and non-carcass components. Crossbred lambs, regardless of diet, showed a greater association of physical characteristics of the carcass, performance, palatability, and less noble cuts. Crossbred lambs, regardless of diet, showed a greater association of physical characteristics of the carcass, performance, palatability, and less noble cuts. BB can be considered an alternative energy source in total replacement of corn. Integrating of machine learning techniques is a useful statistical tool for studies with large numbers of variables, especially when it comes to analyzing complex data with multiple effects in the search for data patterns and insights in decision-making on the farm.

Nutrient utilization, growth performance, and antioxidative status of Barki lambs fed diets supplemented with black (Nigella sativa) and rocket (Eruca sativa) seeds

The current study aimed to determine the polyphenol compounds in Nigella sativa (NS) and Eruca sativa (ES) seeds, and evaluate the impact of their addition either as a sole additive or in combination on the growth performance, digestibility, some rumen and blood parameters and antioxidative status of Barki lambs. Forty-eight male lambs (27.18 ± 0.22 kg, 5-6 months), were divided into 4 balanced groups. The experimental diets were randomly distributed to the control group (CON); fed alfalfa hay plus concentrate feed mixture at a ratio of 30:70% without additives, while, NSD, ESD, and NESD groups: fed CON diet plus 2% NS, 2% ES or 1% NS + 1% ES, respectively as a ratio from total mixed ration (TMR). Results indicated that rutin and catechin were the most phenolic compounds observed either in NS or ES seeds. The NS and ES-supplemented groups recorded the highest (P < 0.05) values for dry matter digestibility, nutritive values, average daily gain, and the best feed conversion ratio. However, growth performance, nutritive value, and all nutrient digestibility except for dry matter were not significantly altered with the NESD group. Concentrations of ruminal NH3-N and TVFA were significantly (P < 0.05) reduced with the NESD group, with no significant differences in pH values among different groups. Values of blood parameters showed significant increases in WBCs, PCV, and T-AOC, and decreases in cholesterol, triglycerides, and MDA with the addition of NS and ES seeds or both. Therefore, the addition of NS and ES seeds is recommended to improve lambs' health and antioxidant status.

Supplementation of Acacia dealbata versus Acacia mearnsii leaf-meal has potential to maintain growth performance of lambs grazing low-quality communal rangelands in South Africa

Supplementing livestock grazing communal rangelands with leaf-meals from Acacia trees, which are currently considered as problematic invasive alien plants globally, may be a sustainable way of exploiting their desirable nutritional and anthelmintic properties. The current study evaluated worm burdens and growth performance of lambs grazing low-quality communal rangelands supplemented with leaf-meals prepared from the invasive alien plant species; Acacia mearnsii or A. dealbata. Forty, three-month-old ewe lambs weighing an average of 18.9 ± 0.60 kg were randomly allocated to four supplementary diets: (1) rangeland hay only (control), (2) commercial protein supplement plus rangeland hay, (3) A. mearnsii leaf-meal plus rangeland hay and (4) A. dealbata leaf-meal plus rangeland hay. All the supplementary diets were formulated to meet the lambs' minimum maintenance requirements for protein. All the lambs were grazed on communal rangelands daily from 0800 to 1400 after which they were penned to allow them access to their respective supplementary diets until 08:00 the following morning. The respective supplementary diets were offered at the rate of 400 g ewe- 1 day- 1 for 60 days. Lambs fed the commercial protein supplement had the highest dry matter intake followed by those fed the Acacia leaf-meals and the control diet, respectively (P ≤ 0.05). Relative to the other supplementary diets, lambs fed the commercial protein supplement and A. dealbata leaf-meal had higher (P ≤ 0.05) final body weight and average daily gains. Dietary supplementation did not affect lamb faecal worm egg counts over the study period (P > 0.05). There was no association between supplementary diets and lamb FAMACHA© scores (P > 0.05). It was concluded that supplementation of Acacia dealbata versus Acacia mearnsii has the potential to emulate commercial protein in maintaining growth performance of lambs grazing communal rangelands in the dry season.

Human social enrichment is linked with reduced mortality in artificially reared ewe lambs

Growth of lambs in an artificial rearing system is key to the economic success of sheep-milking farms. Social enrichment in the form of quiet human contact has been shown to increase growth rates of lambs after weaning, perhaps by reducing stress and enhancing immune function. One hundred fourteen artificially reared dairy ewe lambs were assigned either to a Social condition receiving quiet human company in three 20-min segments per day, or a Control condition without quiet human contact. Feeding and housing conditions were otherwise identical. Starting weights for the Social (M = 6.29 kg; SD = 1.19 kg) and Control (M = 6.38 kg; SD = 0.93 kg) lambs were the same, as were their weights after 3 weeks (Mcontrol  = 8.89 kg, SD = 2.55 kg, Msocial  = 8.63 kg, SD = 2.16 kg). Mortality rates were significantly lower (p = 0.041) in the Social condition (0%) than Control (8%). Thus, social enrichment may be important for the wellbeing of lambs and for economic viability in lamb-rearing.

Economic values of reproductive and growth traits in Chinese Yiling sheep

This study aimed to calculate the economic value (EV) of reproductive and growth traits for Yiling sheep. A bio-economic model was developed to assess the economic value of litter size (LS), litter size at weaning (LSW), age at first lambing (AFL), lambing interval (LI), birth weight (BW), weaning weight (WW), and 6-month body weight (6MW). The sensitivity of the economic value of traits to changes in market prices was also analyzed. In this study, the trait with the highest EV was LSW (427.97 ¥), followed by LS (419.96 ¥), BW (52.13 ¥), 6MW (14.46 ¥), WW (11.03 ¥), AFL (-0.51 ¥), and LI (-9.09 ¥). LS was the most important trait in the production system with a relative economic weight of 22.81%, followed by 6MW and LSW with relative economic weights of 18.98% and 19.01%, respectively. All traits assessed, except AFL and LI, had positive economic values, indicating that genetic improvement of these traits would have a positive impact on profitability. The results of the sensitivity analysis showed that the economic value of AFL was not sensitive to price changes. All growth traits were unaffected by price changes in labor and medical costs. In addition, the LS, LSW, LI, WW, and 6MW were sensitive to changes in liveweight and feed prices. Generally, as feed prices increased, the economic value of all traits except LI and BW decreased. Except for LI and BW, the economic value of all traits increased due to the rise in liveweight prices. This suggested that liveweight and feed prices significantly affect the profitability of the production system.

Developing ovine mammary terminal duct lobular units have a dynamic mucosal and stromal immune microenvironment

The human breast and ovine mammary gland undergo striking levels of postnatal development, leading to formation of terminal duct lobular units (TDLUs). Here we interrogate aspects of sheep TDLU growth as a model of breast development and to increase understanding of ovine mammogenesis. The distributions of epithelial nuclear Ki67 positivity differ significantly between younger and older lambs. Ki67 expression is polarised to the leading edge of the developing TDLUs. Intraepithelial ductal macrophages exhibit periodicity and considerably increased density in lambs approaching puberty. Stromal macrophages are more abundant centrally than peripherally. Intraepithelial T lymphocytes are more numerous in older lambs. Stromal hotspots of Ki67 expression colocalize with immune cell aggregates that exhibit distinct organisation consistent with tertiary lymphoid structures. The lamb mammary gland thus exhibits a dynamic mucosal and stromal immune microenvironment and constitutes a valuable model system that provides new insights into postnatal breast development.

Evolution of the sheep industry and genetic research in the United States: opportunities for convergence in the twenty-first century

The continuous development and application of technology for genetic improvement is a key element for advancing sheep production in the United States. The US sheep industry has contracted over time but appears to be at a juncture where a greater utilization of technology can facilitate industry expansion to new markets and address inefficiencies in traditional production practices. Significant transformations include the increased value of lamb in relation to wool, and a downtrend in large-scale operations but a simultaneous rise in small flocks. Additionally, popularity of hair breeds not requiring shearing has surged, particularly in semi-arid and subtropical US environments. A variety of domestically developed composite breeds and newly established technological approaches are now widely available for the sheep industry to use as it navigates these ongoing transformations. These genetic resources can also address long-targeted areas of improvement such as growth, reproduction and parasite resistance. Moderate progress in production efficiency has been achieved by producers who have employed estimated breeding values, but widespread adoption of this technology has been limited. Genomic marker panels have recently shown promise for reducing disease susceptibility, identifying parentage and providing a foundation for marker-assisted selection. As the ovine genome is further explored and genomic assemblies are improved, the sheep research community in the USA can capitalize on new-found information to develop and apply genetic technologies to improve the production efficiency and profitability of the sheep industry.

On-farm evaluation of growth and reproductive performances of Washera and Gumuz sheep in northwestern Ethiopia: Basics for setting up breeding objectives/goals

Growth and reproductive performance traits are traits of economic importance for sheep selection and productivity improvement interventions. This study aimed at comparative evaluation of growth and reproductive performance traits of sheep in the highland and lowland agro-ecologies of northwestern Ethiopia. Data on growth performance traits were collected from 144 Washera (78 males and 66 females) lambs and 72 Gumuz (37 males and 35 females) lambs. Data on reproductive performance traits were collected from 260 Washera (130 rams and 130 ewes) sheep and 150 Gumuz (75 rams and 75 ewes) sheep. General linear model univariate procedure was employed to analyze the collected data. Breed, the interaction effect between breed and season of birth as well as the interaction effect between breed and type of birth all exerted very high significant effect (P<0.001) on live weight at all age groups. Breed type affected pre-weaning average daily weight gain significantly (P<0.01). Pre-weaning average daily weight gain of Washera (70 g/day) was found much better performance than 60 g/day of Gumuz. Breed type exerts significant (P<0.05) effect on age at first lambing, lambing interval, annual reproductive rate and number of lambs born per ewe life time. Average age at first lambing and lambing interval of Washera sheep were 11.69 months and 9.27 months, respectively. The corresponding values for Gumuz sheep were 12.51 months and 10.43 months, respectively. Production and reproduction performance values of traits varied across the two breeds and sexes as well. These values can be used to set up breeding objectives or goals for selective breeding of sheep giving special emphasis to growth traits believed to have medium heritability values.

Prediction of carcass composition through measurements in vivo and measurements of the carcass of growing Santa Inês sheep

In vivo and carcass measurements were evaluated to predict carcass physical and chemical composition and to list the measurements that best fit the prediction of the composition of growing Santa Inês sheep carcasses. Thirty-three animals were used to measure the loin eye area by ultrasound in vivo (LEAu) and in the carcass. We used 39 animals for biometric measurement in vivo and 42 sheep for morphometric measurement in the carcass. For the physical and chemical compositions of carcasses, dissection of the half left carcass was carried out in 42 animals. The data were submitted to Pearson’s correlation analysis and t test. Simple and multiple linear regressions were performed using a stepwise procedure. All correlations between in vivo measurements and the physical and chemical compositions of carcasses (in kg) were significant, except for LEAu. Biometric measurements and hot (HCW) and cold (CCW) carcass weights were considered as predictors of the carcasses’ physical and chemical compositions. Slaughter body weight (SBW) was the variable that most influenced the equations in the assessment of in vivo measurements and HCW and CCW most influenced the equations for measurements on carcasses. Biometric measurements of Santa Inês sheep can be used together with the SBW to estimate the physical and chemical compositions of carcasses, with emphasis on body compactness index, breast width, wither height, and croup height. The morphometric measurements can be used together with carcass weight to estimate the physical and chemical compositions of carcasses, with emphasis on croup width, carcass compactness index, croup perimeter, external and internal carcass lengths, chest width, and leg length and perimeter. The HCW can be used to predict the physical and chemical composition of carcasses without affecting the accuracy of the prediction model.

Breeding practices and trait preferences of smallholder farmers for indigenous sheep in the northwest highlands of Ethiopia: Inputs to design a breeding program

The aim of this study was to identify breeding practices and trait preferences for indigenous sheep in three districts (Estie, Farta and Lay Gayient) located in the northwest highlands of Ethiopia. Questionnaire survey and choice experiment methods were used to collect data from 370 smallholder farmers. Respondents were selected randomly among smallholder farmers who own sheep in the aforementioned districts. A generalized multinomial logit model was employed to examine preferences for sheep attributes, while descriptive statistics and index values were computed to describe sheep breeding practices. Having the highest index value of 0.36, income generation was ranked as the primary reason for keeping sheep, followed by meat and manure sources. The average flock size per smallholder farmer was 10.21 sheep. The majority of the smallholder farmers (91%) have the experience of selecting breeding rams and ewes within their own flock using diverse criteria. Given the highest index value of 0.34, body size was ranked as a primary ram and ewe selection criteria, followed by coat color. Furthermore, choice modeling results revealed that tail type, body size, coat color, growth rate, horn and ear size have shown significant influences on smallholder farmers' preference for breeding rams (P<0.01). The part-worth utility coefficients were positive for all ram attributes except ear size. For breeding ewes, mothering ability, coat color, body size, lambing interval, growth rate, tail type and litter size have shown significant effects on choice preferences of smallholder farmers (P<0.05). Moreover, significant scale heterogeneity was observed among respondents for ewe attributes (P<0.001). Overall, the results implied that sheep breeding objectives suitable for the northwest highlands of the country can be derived from traits such as linear body measurement, weight and survival at different ages, and lambing intervals. However, selection decisions at the smallholder level should not only be based on estimated breeding values of traits included in the breeding objective but instead, incorporate ways to address farmers' preference for qualitative traits.

Influence of Ascophyllum nodosum algae extract on finishing growth performance and nutrient digestibility of buffalo calves in warm climates

The present experiment was conducted to investigate the effect of using an extract of Ascophyllum nodosum algae (Tasco®, AN) on feed digestibility and finishing performance of buffalo calves. Twenty-four buffalo calves (263.4 ± 7.1 kg, 6 ± 1.2-month-old) were allocated to three treatments as a completely randomized design. The experimental treatments included (1) basal diet without supplement (control diet, AN0), (2) basal diet supplemented with 1% (AN1), and (3) basal diet supplemented with 2% (AN2). The gas production parameters and digestibility of feed as well as growth performance of buffalo calves were investigated. The gas production parameters of the experimental diets were not affected by treatments. The average feed intake on the whole period of experiment in the control and AN1 was maximum and minimum, respectively. The AN1 buffalo calves had the largest final weight, total weight gain throughout the entire period (day 0 to 75) and from day 30 to 60 of the experiment (P < 0.05). In comparison with the control (i.e., AN0), overall, the feed conversion ratio in AN1 and AN2 calves improved by about 21.4 and 16.3%, with the AN1 indicating the most suitable feed conversion ratio (P < 0.05). In comparison with the control, supplementation of diets with algae extract linearly improved (P < 0.05) the digestibility of nutrients. Data suggested that inclusion of algae extract had the best beneficial effects on the performance and digestibility of nutrients in finishing buffaloes. Therefore, it may be beneficial to use algae extract especially in warm or hot regions of the world such as the Khuzestan province, though more experiment is required to ensure its effect on heat stress.

Inclusion of the aerial part and condensed tannin extract from Cistus ladanifer L. in lamb diets - Effects on growth performance, carcass and meat quality and fatty acid composition of intramuscular and subcutaneous fat

Thirty-six lambs were used to evaluate the effect of three levels of Cistus ladanifer condensed tannins (CT; 0, 1.25 and 2.5%) and two ways of CT supply (C. ladanifer aerial parts and C. ladanifer CT extract) on lamb growth performance, carcass composition, meat quality and FA composition of intramuscular and subcutaneous fat. The basal diet was composed of dehydrated lucerne supplemented with 60 g/kg of soybean oil. The highest amount of CT (2.5%) had detrimental effects on growth performance, particularly when the aerial part of C. ladanifer was used. Conversely, 1.25% CT in diets did not affect growth performance and meat quality, and inclusion of C. ladanifer CT extract in diet at this level increased t11-18:1, but not c9,t11-18:2 content in fat. Feeding C. ladanifer CT extract might be a good approach for enhancing the nutritional value of ruminant fat, but further studies are needed to ensure upregulation of endogenous synthesis of c9,t11-18:2.

The effect of including argane by-products (meal and pulp) in dairy ewe diet on milk quality and production, and lamb growth performance

The objective of this work was to study the effect of the incorporation of argane by-products (meal and pulp) in ewe's diet on the production and quality of milk and the performance of lambs in the lactation phase. Twenty ewes were divided into two equal groups. The first one has been fed with argane by-product diet (AD), and the second with a control diet (CD). The results showed an improvement in milk production with an average of 26.3% for AD compared with the CD group. AD group lambs showed a significant difference (p < 0.05) compared with the CD group during lactation phase. The ash and protein levels were not affected by treatments; however, fat, lactose, density, and fusion point content show more fluctuations for both treatments (p < 0.05). The physicochemical parameters of sheep milk showed high (p < 0.01) to very high (p < 0.001) significant change, along the lactation weeks. Except the Zn which showed no significant difference (p > 0.05), the mineral composition of both milks (Na, K, Ca, Mg, P, and Fe) was significant (p < 0.05). It is concluded that, in terms of performances, argane by-products could replace the conventional diet for ewes without substantial detrimental effects. Therefore, argane by-product could be used as a cost-effective feed for sheep in dry areas.

Effect of Texel crossbreeding on productive traits, carcass and meat quality of Segureña lambs

BACKGROUND

The present study aimed to assess the effect of crossbreeding a local breed (Segureña, S × S) with Texel as the sire line (Texel × Segureña crossbred, T × S) on productive traits and meat quality attributes. Sixty-eight lambs (both males and females) from each genotype, weaned at about 45 days old and intensively fed with concentrates and cereal straw ad libitum until they were 72 days old, were used to assess productive traits, and ten animals from each genotype were used to assess meat quality.

RESULTS

The crossbreeding with Texel improves productivity, with a greater weight at birth (+1 kg) and at slaughter (+3 kg) and a greater average daily gain (+29 g). T × S lambs had a better conformation, less carcass fatness, and higher content of muscle (+45 g kg^-1 ) as opposed to a lower fat content (-50.6 g kg^-1 ). With regard to meat quality, crossbreeding with Texel provided a meat with a higher protein content (+4 g kg^-1 ) and a lower oleic acid content (21% less), although the differences were very scarce from a sensory point of view, and non-existent with respect to instrumental quality.

CONCLUSION

Crossbreeding could comprise a useful tool in the production of ovine meat in local breeds, such as Segureña, within the Mediterranean Area, and, consequently, a way of increasing the profitability of the farms. © 2018 Society of Chemical Industry.

Influence of dietary cardoon meal on growth performance and selected meat quality parameters of lambs, and the antioxidant potential of cardoon extract in ovine muscle homogenates

Fatty acids and oxidative stability were determined in meat from lambs fed a diet containing 15% dehydrated alfalfa (CON, n = 8) or cardoon meal (CMD, n = 7). Furthermore, the antioxidant activity of a phenolic-rich cardoon meal extract (1.32 GAE mg/ml) was examined in muscle homogenates (0, 0.5, 1, 5% v/w) subjected to iron/ascorbate-induced oxidation. Feeding CMD did not affect lamb performances and carcass traits but reduced (P < 0.05) the vaccenic and rumenic acids and increased stearic acid in muscle. Lipid oxidation was higher in raw meat from the CMD-fed lambs after 7 days of storage (P < 0.05). Feeding CMD did not affect the colour stability of raw meat and the oxidative stability of cooked meat and of muscle homogenates incubated with pro-oxidant catalysts. Adding 5% cardoon extract in muscle homogenates increased (+114.3%; P = 0.03) the total phenolic content and reduced (-77.6%; P < 0.01) lipid oxidation, demonstrating the antioxidant potential of compounds present in cardoon meal.

A pilot study of the effects of Mycoplasma ovipneumoniae exposure on domestic lamb growth and performance

Mycoplasma ovipneumoniae is a globally distributed pathogen that has been associated with pneumonia in both domestic and wild Caprinae. It is closely related to M. hyopneumoniae, a respiratory pathogen of swine that is associated with decreased growth rates of pigs as well as clinical respiratory disease. In order to assess the effects of M. ovipneumoniae on lamb performance, we generated a cohort of lambs free of M. ovipneumoniae by segregation of test negative ewes after lambing, then compared the growth and carcass quality traits of M. ovipneumoniae-free and -colonized lambs from weaning to harvest. Some signs of respiratory disease were observed during the feeding trial in both lamb groups, but the M. ovipneumoniae-exposed group included more affected lambs and higher average disease scores. At harvest, lungs of lambs in both groups showed few grossly visible lesions, although the M. ovipneumoniae-exposed group did exhibit increased microscopic lung lesions (P<0.05). In addition, M. ovipneumoniae exposed lambs produced lower average daily gains (P<0.05), and lower yield grade carcasses (P<0.05) compared to those of non-exposed lambs. The results demonstrated the feasibility of test and segregation for elimination of M. ovipneumoniae from groups of sheep and suggested that this pathogen may impair lamb growth and productivity even in the absence of overt respiratory disease.

Effect of dietary neutral detergent fibre source on lambs growth, meat quality and biohydrogenation intermediates

With this trial we have tested the effects of structural and chemical composition of neutral detergent fibre (NDF) of the diet on lamb fatty acid composition of meat and subcutaneous fat. Twenty lambs, were fed complete diets with low starch and similar NDF content of different origin (ground alfalfa or soybean hulls). Animal performance and product quality were not affected by treatments. Rumen pH increased and parakeratosis intensity decreased with the level of alfalfa in the diet. Increasing the alfalfa proportion in the diet decreased t10-18:1 (P = .023), increased t11-18:1 (P = .003) and decreased the t10/t11 ratio according to a quadratic pattern (P = .020). Chemical composition and structure of the diet's fibrous fraction influenced the BI pattern of the final product. Forty percent of alfalfa in diet reduced the severity of t10-shift, but for its full resolution, other factors should be considered including forage particle size and buffering capacity of the diet.

Grape pomace (Vitis vinifera L. cv. Pinotage) supplementation in lamb diets: Effects on growth performance, carcass and meat quality

This study investigated the effects of feeding graded levels of sun-dried red grape pomace (GP; 0, 5, 10, 15 and 20%) on growth, carcass and meat physico-chemical quality attributes of Dohne Merino lambs for 42 days. Dry matter intake increased quadratically with a critical value (i.e., optimum inclusion level) of 11.3% GP (P ≤ 0.05). Diet exhibited similar quadratic responses for average daily gain, live, hot and cold carcass weights with optimum inclusion levels at 9.6, 9.7, 12, 2 and 12.1, respectively (P ≤ 0.05). Overall, meat quality traits were not negatively affected by GP inclusion (P > .05). Gross profit was influenced by diet, with an optimum inclusion level at 12.2% (quadratic; P ≤ 0.05). Overall, inclusion of 12.2% GP in lamb finishing diets at the expense of oat bran and wheat bran middlings improved lamb productivity, without compromising meat quality.

Dietary vitamin E dosage and source affects meat quality parameters in light weight lambs

BACKGROUND

Supra-nutritional vitamin E supplementation is a commonly used approach to delay lipid oxidation and colour deterioration in lamb and beef meat marketed under modified atmosphere packaging. However, these applications lack a precise calibration of dose for the desired effect and, in addition, limited information is available regarding the use of natural vitamin E for this purpose.

RESULTS

Three hundred and sixty Rasa Aragonesa lambs were fed diets supplemented with all-rac-α-tocopheryl acetate (250, 500, 1000 and 2000 mg kg^-1 compound feed), RRR-α-tocopheryl acetate (125, 250, 500 and 1000 mg kg^-1 compound feed) and a basal diet without vitamin E supplementation for 14 days before slaughter at 25.8 ± 1.67 kg body weight. Vitamin E supplementation had no effect (P > 0.05) on average daily weight gain, feed intake and feed efficiency. Display time had larger effects on lipid oxidation, colour stability, myoglobin forms and meat discolouration parameters compared to vitamin E supplementation. However, vitamin E source and dosage significantly extended meat shelf-life as indicated by lipid oxidation, redness, hue angle, metmyoglobin formation, deoxymyoglobin formation, A_580-630 and I_SO2 .

CONCLUSION

The quantification of these effects demonstrated that the biological activity value of 1.36 used to distinguish both vitamin E sources is not appropriate for meat quality enhancing properties. © 2017 Society of Chemical Industry.

Assessing the protective effect of bentonite against lead toxicity in growing lambs

The objective of the present experiment was to investigate the effect of bentonite supplementation in lead (Pb)-exposed lambs on serum Pb, Ca, P, Cu, Zn, and Fe concentrations, blood hematological parameters, and hepatic enzymes. Twenty Zandi male lambs (initial BW, 17.5 ± 1.6 kg) were randomly assigned to one of the four treatments: (1) control (no Pb or bentonite), (2) 15 mg/kg DM Pb as Pb acetate with no bentonite, (3) 15 mg/kg DM Pb as Pb acetate with 1.5% bentonite, and (4) 15 mg/kg DM Pb as Pb acetate with 3% bentonite. The experiment lasted after 90 days. Lead intake resulted in a decrease (P < 0.05) in serum Fe and an increase in serum Pb, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) activities (P < 0.05). Bentonite supplementation at 1.5 or 3% of DM decreased blood Pb concentration (P < 0.01) in lambs fed diets containing Pb and reduced (P < 0.05) blood concentration of Cu and Zn compared to control group (P < 0.01). However, the hematological parameters were not affected by any of the treatments. Our results showed that the dietary supplementation of bentonite could protect lambs against lead toxicity.

Intravenous maternal -arginine administration to twin-bearing ewes, during late pregnancy, is associated with increased fetal muscle mTOR abundance and postnatal growth in twin female lambs

The aims of this study were to determine whether parenteral Arg administered to well-fed twin-bearing ewes from 100 to 140 d of pregnancy influences fetal skeletal muscle growth, the abundance and activation of mechanistic target of rapamycin (mTOR) protein, and postnatal muscle growth of the offspring. Ewes fed 100% of NRC-recommended nutrient requirements for twin-bearing ewes were administered an intravenous bolus of either 345 μmol Arg HCl/kg BW or saline solution (Control) 3 times per day. At 140 d of pregnancy (P140), a group of 11 Control and 9 Arg-treated ewes were euthanized and hind leg muscles and longissimus dorsi (LD) were excised and weighed. A sample of LD was snap frozen in liquid nitrogen for later analysis of free AA (FAA) concentration, mTOR abundance and phosphorylation, and biochemical indices (DNA, RNA, and protein content). For the remaining 25 ewes (Arg, = 13, and Control, = 12), Arg administration was continued until the initiation of parturition and ewes were allowed to lamb. Lambs were weaned at postnatal Day 82 and grazed on pasture until postnatal day 153 (PN153), when a subset of 20 lambs ( = 10 per group) was euthanized. At P140, only the psoas major was heavier in the Arg-administered group compared with the Control group. Female lambs from ewes supplemented with Arg (Arg-F) had increased abundance of total mTOR, RNA concentration, and RNA:DNA ratio in LD compared with female lambs from Control ewes (Con-F), whereas males did not differ. At PN153, Arg-F were heavier than Con-F and had heavier LD and plantaris and a trend for heavier psoas major muscles compared with Con-F. In contrast, BW and individual muscle weights did not differ in male lambs. Lambs from Arg-treated ewes had heavier semimembranosus and tended to have heavier biceps femoris compared with Control lambs. The RNA concentration in LD was greater in Arg-F compared with Con-F, and DNA concentration was greater in the Arg group compared with the Control group. In conclusion, Arg administration to the ewe during gestation increases female lamb weight and muscle weight after birth and these changes are associated with altered mTOR protein abundance and have potential implications for sheep production.

Nutritional enhancement of sheep meat fatty acid profile for human health and wellbeing

Dietary fatty acids (FA) consumed by sheep, like other ruminants, can undergo biohydrogenation resulting in high proportions of saturated FA (SFA) in meat. Biohydrogenation is typically less extensive in sheep than cattle, and consequently, sheep meat can contain higher proportions of omega (n)-3 polyunsaturated FA (PUFA), and PUFA biohydrogenation intermediates (PUFA-BHI) including conjugated linoleic acid (CLA) and trans-monounsaturated FAs (t-MUFA). Sheep meat is also noted for having characteristically higher contents of branched chain FA (BCFA). From a human health and wellness perspective, some SFA and trans-MUFA have been found to negatively affect blood lipid profiles, and are associated with increased risk of cardiovascular disease (CVD). On the other hand, n-3 PUFA, BCFA and some PUFA-BHI may have many potential beneficial effects on human health and wellbeing. In particular, vaccenic acid (VA), rumenic acid (RA) and BCFA may have potential for protecting against cancer and inflammatory disorders among other human health benefits. Several innovative strategies have been evaluated for their potential to enrich sheep meat with FA which may have human health benefits. To this end, dietary manipulation has been found to be the most effective strategy of improving the FA profile of sheep meat. However, there is a missing link between the FA profile of sheep meat, human consumption patterns of sheep FA and chronic diseases. The current review provides an overview of the nutritional strategies used to enhance the FA profile of sheep meat for human consumption.

Performance and carcass characteristics of lambs fed diets with increasing levels of Mimosa tenuiflora (Willd.) hay replacing Buffel grass hay

This study evaluated the performance and carcass characteristics of lambs fed diets with increasing levels of Mimosa tenuiflora (Willd.) hay replacing Buffel grass (Cenchrus ciliaris). Twenty-eight Santa Inês male lambs with an average body weight (BW) of 20.3 ± 1.49 kg(mean ± SD) were allocated in individual stalls and distributed in a completely random design with four treatments (0, 20, 40, and 60 g/100 g total DM M. tenuiflora hay replacing Buffel grass hay in diet) with seven replications. M. tenuiflora hay at the level of 20% dry matter (DM) total replacing Buffel grass hay increased final weight (P = 0.006), total weight gain (P < 0.001), average daily weight gain (ADWG; P < 0.001), DM intake (P < 0.001), and feed efficiency (P < 0.001). Intake of crude protein, NDF_ap, ADF_ap, ash, ether extract, total and non-fibrous carbohydrates, and total digestible nutrients presented a positive quadratic effect with M. tenuiflora hay replacing Buffel grass hay and 40 g/100 g total DM level presented greater intake. There were positive quadratic effects by M. tenuiflora hay inclusion at 20 g/100 g total DM level on slaughtering weight (P = 0.005), hot carcass weight (P = 0.002), cold carcass weight (P = 0.002), empty body weight (P = 0.001), hot carcass yield (P = 0.002), cold carcass yield (P = 0.003), and increase linear on biological yield (P = 0.003). There was no influence on cooling weight loss (P = 0.284). M. tenuiflora hay may be included in lamb diets at amounts up to 20 g/100 g total DM substitution of Buffel grass hay because increase in the nutrients intake, growth performance, and carcass characteristics.

Evaluation of Crossbreeding of Australian Superfine Merinos with Gansu Alpine Finewool Sheep to Improve Wool Characteristics

Crossbreeding of Australian Superfine Merinos (ASMs) with Gansu Alpine Finewool (GAF) sheep and an evaluation of the potential benefits of this genetic cross has not been previously conducted. 13 ASMs were crossbred with GAF sheep over a five year period with backcrossing designed to assess heterosis. Data from 11,178 lambs sired by 189 rams were used in the study. Genotype, birth year, birth type, dam age, sex and/or management group, and record age were fitted as fixed effects and within-genotype sire fitted as a random effect. Crossbreeds of 1/2 ASM expressed the most desirable effects for improving average fiber diameter (AFD), clean fleece weight (CFW), yield, coefficient of variation of AFD (CVAFD), yearling staple length (YSL) to AFD ratio (YSL/AFD), and CFW to metabolic yearling bodyweight (YWT^0.75) ratio (CFW/YWT^0.75) but showed the least post-weaning average daily gain (powADG) and YWT. Genotype of backcrossing with 1/4 ASM obtained moderate improvements in AFD, CFW, CVAFD, and YSL/AFD but the highest YSL, WWT, and prwADG. Except for yield (-1.42%) and CFW/YWT^0.75 (-1%), heterosis estimates were generally low and positive, and ranged from 0.1% for CVAFD to 4% for powADG, which indicates the potential to improve relevant traits through exploiting heterosis to a varying extent. The ASMs sampled in this study were found to be superior to GAFs for AFD, CFW, yield, and CVAFD by 19.82%, 11.68%, 14.47%, and 6.99%, respectively, but inferior for YSL, PowADG, and YWT by 4.36%, 50.97%, and 16.93%, respectively. ASMs also appeared to be more efficient than GAFs in clean wool production (25.34%) and staple length growth (16.17%). The results of our study strongly suggest that an infusion of ASM genes via crossbreeding is an effective and appropriate approach to improve wool microns and wool production from GAF sheep, and we make recommendations to tackle the undesirable traits of YWT and YSL from ASM introduction.

Effects of feed intake and genetics on tissue nitrogen-15 enrichment and feed conversion efficiency in sheep

This study investigated the effects of sheep genetics and feed intake on nitrogen isotopic fractionation (ΔN) and feed conversion efficiency (FCE; live weight gain/DMI), using a 2 × 2 factorial design, with 2 levels of genetic merit for growth (high vs. low) and 2 levels of feed intake (110 vs. 170% of ME for maintenance [MEm]). No effect of genetic merit was detected for live weight gain ( = 0.64), FCE ( = 0.46), plasma urea nitrogen ( = 0.52), plasma glucose ( = 0.78), and ΔN of wool ( = 0.45), blood ( = 0.09), and plasma ( = 0.51). Sheep receiving 170% of MEm had 175% higher live weight gain ( < 0.001) and 77% higher FCE ( < 0.001) than sheep receiving 110% of MEm. There was no difference among treatments at the beginning of the study for either blood or plasma ∆N, but the treatment groups started to diverge in blood and plasma ∆N at 21 and 7 d, respectively. Blood, plasma, and wool samples were enriched in N compared with feed. There was a higher blood, plasma, and wool ∆N for the low feed intake group than the high feed intake group ( < 0.001 in all cases). Across the 4 treatment groups, higher FCE in sheep was associated with lower ∆N for plasma, blood, and wool. Overall, the results are consistent with the potential of ∆N as a rapid, low-cost biomarker of FCE in sheep, despite there being no effects of genetic treatment on FCE and ∆N.

Body weight and reproductive parameters in fast and weak growing Awassi ram lambs during different age stages

This study was carried out on 30 Syrian Awassi ram lambs around 3 months of age. Lambs were divided equally in 2 groups as fast growing (FG) and weak growing (WG) lambs to identify body weight and reproductive parameters in each group during different age stages. Blood samples were collected to determine testosterone and leptin concentrations using radioimmunoassay. At puberty, average body weight and age of FG and WG lambs was 52.4 and 43.1 kg, and 225.9 and 248.0 days, respectively, with a significant (P < 0.05) difference between them in both parameters. Testosterone concentration was very low at 3 months of age (below 1.0 nmol L(-1)) and increased with advancing age with a sharp increase occurring at 7 months of age and at puberty, averages were 12.58 and 11.86 nmol L(-1) for FG and WG groups, respectively, with no significant (P > 0.05) differences. At puberty, average leptin concentration was 3.16 and 2.98 ng mL(-1) for FG and WG groups, respectively, with no significant (P > 0.05) difference.

Genome-wide association study for wool production traits in a Chinese Merino sheep population

Genome-wide association studies (GWAS) provide a powerful approach for identifying quantitative trait loci without prior knowledge of location or function. To identify loci associated with wool production traits, we performed a genome-wide association study on a total of 765 Chinese Merino sheep (JunKen type) genotyped with 50 K single nucleotide polymorphisms (SNPs). In the present study, five wool production traits were examined: fiber diameter, fiber diameter coefficient of variation, fineness dispersion, staple length and crimp. We detected 28 genome-wide significant SNPs for fiber diameter, fiber diameter coefficient of variation, fineness dispersion, and crimp trait in the Chinese Merino sheep. About 43% of the significant SNP markers were located within known or predicted genes, including YWHAZ, KRTCAP3, TSPEAR, PIK3R4, KIF16B, PTPN3, GPRC5A, DDX47, TCF9, TPTE2, EPHA5 and NBEA genes. Our results not only confirm the results of previous reports, but also provide a suite of novel SNP markers and candidate genes associated with wool traits. Our findings will be useful for exploring the genetic control of wool traits in sheep.

Replacing cottonseed meal with ground Prosopis juliflora pods; effect on intake, weight gain and carcass parameters of Afar sheep fed pasture hay basal diet

The experiment was conducted to determine the supplementary feeding value of ground Prosopis juliflora pod (Pjp) and cottonseed meal (CSM) and their mixtures on feed intake, body weight gain and carcass parameters of Afar sheep fed a basal diet of pasture hay. Twenty-five yearling fat-tailed Afar rams with mean initial live weight 17.24 ± 1.76 kg (mean ± SD) were used in a randomized complete block design. Animals were blocked on their initial body weight. The experiment was conducted for 12 weeks and carcass evaluation followed. Treatments were hay alone ad libitum (T 1) or with 300 g CSM (T 2), 300 g Pjp (T 5), 2:1 ratio (T 3) and 1:2 ratio of CSM : Pjp (T 4). The CP contents of the hay, CSM and Pjp were 10.5, 44.5 and 16.7 %, respectively. Hay DM intake was higher (P < 0.05) for non-supplemented and total DM intake was lower in non-supplemented. Average daily weight gain (ADG) was lower (P < 0.05) for T 1 compared to all supplemented treatments except T 5. Hot carcass weight and rib-eye muscle area also followed the same trend like that of ADG. Compared with feeding hay alone, supplementing with CSM or a mixture of CSM and Pjp appeared to be a better feeding strategy, biologically, for yearling Afar rams.

Using dual-purpose crops in sheep-grazing systems

The utilisation of dual-purpose crops, especially wheat and canola grown for forage and grain production in sheep-grazing systems, is reviewed. When sown early and grazed in winter before stem elongation, later-maturing wheat and canola crops can be grazed with little impact on grain yield. Recent research has sought to develop crop- and grazing-management strategies for dual-purpose crops. Aspects examined have been grazing effects on crop growth, recovery and yield development along with an understanding of the grazing value of the crop fodder, its implications for animal nutrition and grazing management to maximise live-weight gain. By alleviating the winter 'feed gap', the increase in winter stocking rate afforded by grazing crops allows crop and livestock production to be increased simultaneously on the same farm. Integration of dual-purpose wheat with canola on mixed farms provides further systems advantages related to widened operational windows, weed and disease control and risk management. Dual-purpose crops are an innovation that has potential to assist in addressing the global food-security challenge.

Building integral projection models: a user's guide

In order to understand how changes in individual performance (growth, survival or reproduction) influence population dynamics and evolution, ecologists are increasingly using parameterized mathematical models. For continuously structured populations, where some continuous measure of individual state influences growth, survival or reproduction, integral projection models (IPMs) are commonly used. We provide a detailed description of the steps involved in constructing an IPM, explaining how to: (i) translate your study system into an IPM; (ii) implement your IPM; and (iii) diagnose potential problems with your IPM. We emphasize how the study organism's life cycle, and the timing of censuses, together determine the structure of the IPM kernel and important aspects of the statistical analysis used to parameterize an IPM using data on marked individuals. An IPM based on population studies of Soay sheep is used to illustrate the complete process of constructing, implementing and evaluating an IPM fitted to sample data. We then look at very general approaches to parameterizing an IPM, using a wide range of statistical techniques (e.g. maximum likelihood methods, generalized additive models, nonparametric kernel density estimators). Methods for selecting models for parameterizing IPMs are briefly discussed. We conclude with key recommendations and a brief overview of applications that extend the basic model. The online Supporting Information provides commented R code for all our analyses.

Transcriptome profile at different physiological stages reveals potential mode for curly fleece in Chinese tan sheep

Tan sheep (Ovis aries), a Chinese indigenous breed, has special curly fleece after birth, especially at one month old. However, this unique phenotype disappears gradually with age and the underlying reasons of trait evolvement are still unknown. In this study, skin transcriptome data was used to study this issue. In total 51,215 transcripts including described transcripts and transfrags were identified. Pathway analysis of the top 100 most highly expressed transcripts, which included TCHH and keratin gene family members, such as KRT25, KRT5, KRT71, KRT14 and others, showed pathways known to be relevant to hair/fleece development and function. Six hundred differentially expressed (DE) transcripts were detected at two different physiological ages (one-month-old with curly fleece and 48-month-old without curly fleece) and were categorized into three major functional groups: cellular component, molecular function, and biological process. The top six functional categories included cell, cell part, cellular process, binding, intracellular, metabolic process. The detected differentially expressed genes were particularly involved in signal, signal peptide, disulfide bond, glycoprotein and secreted terms, respectively. Further splicing isoform analysis showed that the metallothionein 3 isoform was up-regulated in Tan lamb skin, indicating that it may be related to the conformation of curly fleece in Chinese Tan lamb. The hair-related important differentially expressed genes (SPINK4, FGF21, ESRα, EphA3, NTNG1 and GPR110) were confirmed by qPCR analysis. We deduced that the differences existed in expressed transcripts, splice isoforms and GO categories between the two different physiological stages, which might constitute the major reasons for explaining the trait evolvement of curly fleece in Chinese Tan sheep. This study provides some clues for elucidating the molecular mechanism of fleece change with age in Chinese Tan sheep, as well as supplying some potential values for understanding human hair disorder and texture changes.

Castor beans hulls as a replacement for Tifton 85 hay in lamb diets

The objective of this study was to evaluate the effect of replacing Tifton 85 hay (0, 33, 66, or 100 %) with by castor bean hulls on the intake and nutrient digestibility and performance of 28 noncastrated lambs, averaging 7 months in age, 19.5 ± 2.0 kg average live weight, fed on diets based on forage cactus. The animals were housed in individual pens for 100 days. The digestibility trial occurred 40 days after the start of the performance using LIPE® as an external indicator for estimating fecal dry matter production. The replacement of hay with Castor beans hulls linearly decreased the intakes of dry matter, neutral detergent fiber, organic matter, and crude protein and reduced the digestibility coefficients of the dry matter, neutral detergent fiber, organic matter content, crude protein, and total digestible nutrient content. The hot carcass and true carcass yields were not influenced by the treatments and the feed conversion increased linearly. The empty body weight, live weight at slaughter, hot and cold carcass weights, total gain, and average daily gain decreased linearly with the replacement. The replacement of Tifton 85 hay with castor bean hulls reduced the intake of dry matter, crude protein and energy, consequently reducing the performance of the animals. However, as the regression coefficients were of low magnitude, data were subjected to analysis of variance and means were compared using the Dunnett test with diet without castor bean hulls set as the control treatment. The Tifton 85 hay can be replaced up to 66 % by castor bean hulls in finishing diets for lambs.

Sheepmeat flavor and the effect of different feeding systems: a review

Lamb has a unique flavor, distinct from other popular red meats. Although flavor underpins lamb's popularity, it can also be an impediment to consumer acceptance. Lack of familiarity with sheepmeat flavor itself can be a barrier for some consumers, and undesirable feed-induced flavors may also compromise acceptability. Against the backdrop of climate uncertainty and unpredictable rainfall patterns, sheep producers are turning to alternatives to traditional grazing pasture systems. Historically, pasture has been the predominant feed system for lamb production in Australia and around the world. It is for this reason that there has been a focus on "pastoral" flavor in sheep meat. Pasture-associated flavors may be accepted as "normal" by consumers accustomed to meat from pasture-fed sheep; however, these flavors may be unfamiliar to consumers of meat produced from grain-fed and other feed systems. Over the past few decades, studies examining the impacts of different feeds on lamb meat quality have yielded variable consumer responses ranging from "no effect" to "unacceptable", illustrating the diverse and sometimes inconsistent impacts of different forages on sheepmeat flavor. Despite considerable research, there is no consensus on which volatiles are essential for desirable lamb aroma and how they differ compared to other red meats, for example, beef. In contrast, comparatively little work has focused specifically on the nonvolatile taste components of lamb flavor. Diet also affects the amount of intramuscular fat and its fatty acid composition in the meat, which has a direct effect on meat juiciness and texture as well as flavor, and its release during eating. The effect of diet is far from simple and much still needs to be learned. An integrated approach that encompasses all input variables is required to better understand the impact of the feed and related systems on sheepmeat flavor. This review brings together recent research findings and proposes some novel approaches to gain insights into the relationship between animal diet, genetics, and sheepmeat quality.

Knockdown of myostatin expression by RNAi enhances muscle growth in transgenic sheep

Myostatin (MSTN) has been shown to be a negative regulator of skeletal muscle development and growth. MSTN dysfunction therefore offers a strategy for promoting animal growth performance in livestock production. In this study, we investigated the possibility of using RNAi-based technology to generate transgenic sheep with a double-muscle phenotype. A shRNA expression cassette targeting sheep MSTN was used to generate stable shRNA-expressing fibroblast clones. Transgenic sheep were further produced by somatic cell nuclear transfer (SCNT) technology. Five lambs developed to term and three live lambs were obtained. Integration of shRNA expression cassette in three live lambs was confirmed by PCR. RNase protection assay showed that the shRNAs targeting MSTN were expressed in muscle tissues of three transgenic sheep. MSTN expression was significantly inhibited in muscle tissues of transgenic sheep when compared with control sheep. Moreover, transgenic sheep showed a tendency to faster increase in body weight than control sheep. Histological analysis showed that myofiber diameter of transgenic sheep M17 were bigger than that of control sheep. Our findings demonstrate a promising approach to promoting muscle growth in livestock production.

Ghrelin promotion of oocyte maturation via ERK1/2 pathway in ovis aries

Ghrelin has recently garnered increasing attention in biomolecular studies. Ghrelin's growth hormone secretagogue receptor type 1a (GHS--R) is a pleiotropic modulator of diverse biological functions, including energy homeostasis and reproduction. This study sought to understand the ways in which ghrelin impacts ERK1/2 and p90rsk during the ovis aries oocyte maturation process. We applied different concentrations of ghrelin and of ghrelin receptor inhibitor (D--Lys3--GHRP--6) to ovis aries oocytes and observed the effects on the ERK1/2 and p90rsk pathway. The ERK1/2 and p90rsk pathway plays an essential role in the in vitro maturation of ovis aries oocytes. This study discovered that ERK1/2 and p90 rsk pathway, during the ovis aries oocyte maturation, was associated with maturation of ovis aries oocyte in vitro.

Effect of high-dose nano-selenium and selenium-yeast on feed digestibility, rumen fermentation, and purine derivatives in sheep

The aim of this study was to evaluate the effect of nano-selenium (NS) and yeast-selenium (YS) supplementation on feed digestibility, rumen fermentation, and urinary purine derivatives in sheep. Six male ruminally cannulated sheep, average 43.32 ± 4.8 kg of BW, were used in a replicated 3 × 3 Latin square experiment. The treatments were control (without NS and YS), NS with 4 g nano-Se (provide 4 mg Se), and YS with 4 g Se-yeast (provide 4 mg Se) per kilogram of diet dry matter (DM), respectively. Experimental periods were 25 days with 15 days of adaptation and 10 days of sampling. Ruminal pH, ammonia N concentration, molar proportion of propionate, and ratio of acetate to propionate were decreased (P < 0.01), and total ruminal VFA concentration was increased with NS and YS supplementation (P < 0.01). In situ ruminal neutral detergent fiber (aNDF) degradation of Leymus chinensis (P < 0.01) and crude protein (CP) of soybean meal (P < 0.01) were significantly improved by Se supplementation. Digestibilities of DM, organic matter, crude protein, ether extract, aNDF, and ADF in the total tract and urinary excretion of purine derivatives were also affected by feeding Se supplementation diets (P < 0.01). Ruminal fermentation was improved by feeding NS, and feed conversion efficiency was also increased compared with YS (P < 0.01). We concluded that nano-Se can be used as a preferentially available selenium source in ruminant nutrition.

Tifton hay, soybean hulls, and whole cottonseed as fiber source in spineless cactus diets for sheep

The objective of this paper was to evaluate the effect of three different sources of fiber (tifton hay, soybean hulls, and whole cottonseed) in spineless cactus diets for sheep in the semiarid region of northeastern Brazil. Twenty-one sheep in finishing phase with indeterminate breed, non-castrated, and with initial weight of 18.90 ± 1.07 kg were randomly distributed to individual stalls where they were confined for the duration of the experiment. The intakes of dry and organic matter, total carbohydrates, and total digestive nutrients were not influenced (P > 0.10) by the different fiber sources (1.10, 0.97, 0.73, and 0.80 kg/day, respectively). However, sheep which received the whole cottonseed diet were characterized by a lower (P < 0.10) intake of crude protein and neutral detergent fiber and greater (P < 0.10) intake of ether extract (0.11, 0.29, and 0.048 kg/day, respectively). The different sources of fiber resulted in similar times spent feeding (P > 0.10), although the rumination time was greater for tifton hay (P < 0.10) (429.05 min/day). The digestibility coefficient of dry and organic matter differed between the treatments (P < 0.10), with the soybean hull diet showing a higher level of digestion (83.23 and 86.72 %, respectively). The whole cottonseed diet gave the smallest digestibility coefficient of crude protein (68.95 %) and greatest for ether extract (85.94 %). The daily weight gain of animals fed on whole cottonseed was significantly lower (P < 0.10). On the basis of these findings, we recommend the use of tifton hay or soybean hulls as important additional source of fiber in forage spineless cactus diets for sheep in finishing phase.

Effect of legume grains as a source of dietary protein on the quality of organic lamb meat

BACKGROUND

This study evaluated the effects on lamb growth, carcass traits and meat quality of replacing conventional soybean meal in the diet with alternative legume grains.

RESULTS

Twenty-eight male lambs of Comisana breed weighing 16.9 ± 2.7 kg at weaning (66 ± 6 days old) were assigned to one of four diets. Until slaughter at 129 ± 6 days of age, each group received ad libitum pelleted alfalfa hay and concentrates differing in the source of protein: chickpea, faba bean, pea or soybean meal. Lambs fed chickpea showed higher dry matter and protein intakes from concentrate than those fed soybean. Lambs' growth, carcass weight and net dressing percentage did not vary by protein source, although chickpea lambs had more perirenal and pelvic fat than those in the soybean group. Diet did not affect chemical composition, colour, thawing and cooking losses, tenderness, and sensory properties of meat. Chickpea increased trans-vaccenic and linoleic acid, and chickpea and faba bean increased the isomers of conjugated linoleic acid.

CONCLUSIONS

Legume grains can completely replace soybean meal in concentrate, resulting in lamb carcasses and meat of comparable quality. Chickpea leads to an increase in feed intake of lambs and in fat depots in the carcass, and a more beneficial fatty acid profile.

Methanogen colonisation does not significantly alter acetogen diversity in lambs isolated 17 h after birth and raised aseptically

Reductive acetogenesis is not competitive with methanogenesis in adult ruminants, whereas acetogenic bacteria are the dominant hydrogenotrophs in the early rumen microbiota. The ecology of hydrogenotrophs in the developing rumen was investigated using young lambs, raised in sterile isolators, and conventional adult sheep. Two lambs were born naturally, left with their dams for 17 h and then placed into a sterile isolator and reared aseptically. They were inoculated with cellulolytic bacteria and later with Methanobrevibacter sp. 87.7 to investigate the effect of methanogen establishment on the rumen acetogen population since they lacked cultivable representatives of methanogens. Putative acetogens were investigated by acetyl-CoA synthase and formyltetrahydrofolate synthetase gene analysis and methanogens by methyl coenzyme reductase A gene analysis. Unexpectedly, a low abundant but diverse population of methanogens (predominantly Methanobrevibacter spp.) was identified in isolated lambs pre-inoculation with Mbb. sp 87.7, which was similar to the community structure in conventional sheep. In contrast, potential acetogen diversity in isolated lambs and conventional sheep was different. Potential acetogens affiliated between the Lachnospiraceae and Clostridiaceae in conventional sheep and with the Blautia genus and the Lachnospiraceae in isolated lambs. The establishment of Mbb. sp. 87.7 (1,000-fold increase in methanogens) did not substantially affect acetogen diversity.

Influence of saponins and tannins on intake and nutrient digestion of alkaloid-containing foods

BACKGROUND

We hypothesized that eating a food containing saponins (SAP), or tannins (TAN) prior to foods containing the alkaloids gramine (GRA) or 5-methoxy-N,N-dimethyltryptamine (TRP) would provide benefits not possible when the alkaloid-containing foods were eaten alone.

METHODS

In Trial 1, four groups of five lambs were first offered food with SAP for 30 min followed by food with either GRA or TRP for 3.5 h in a 2 × 2 factorial arrangement of a completely randomized design that included alkaloid (GRA or TRP) with or without SAP. In Trial 2 TAN replaced SAP. All foods were isocaloric (3.3 Mcal kg⁻¹) and isonitrogenous (14% crude protein). Foods, fecal and urine samples were collected and analyzed for dry matter intake and apparent digestibility of dry matter, energy (in megajoules, MJ), nitrogen (N), and neutral detergent fiber.

RESULTS

Supplemental SAP did not affect digestibility of the parameters tested (P > 0.10). Supplemental TAN increased digestibility of N (g kg⁻¹, P = 0.04), N retained (g day⁻¹, P = 0.07), N digested (g day⁻¹, P = 0.06), and N retained/N consumed (g kg⁻¹, P = 0.07). However, digestibilities of dry matter (g kg⁻¹, P = 0.0026), energy (MJ 1000 MJ⁻¹, P = 0.003), neutral detergent fiber (g kg⁻¹, P = 0.008), and digested N retained (g kg⁻¹, P = 0.07) were lower for lambs fed TAN than for unsupplemented animals.

CONCLUSIONS

Tannin supplementation can improve retention of nitrogen in animals fed alkaloid-containing grasses such as reed canarygrass and tall fescue. Combinations of forages with complementary primary and secondary compounds enable animals to maintain intake and improve nutrient utilization.

Effect of roughage to concentrate ratio of sweet sorghum (Sorghum biclor L. Moench) bagasse-based complete diet on nutrient utilization and microbial N supply in lambs

An experiment was conducted to study the effect of roughage to the concentrate ratio of complete diets containing sweet sorghum bagasse (SSB), an agro-industrial by product, as sole roughage source on nutrient utilization in ram lambs. Twenty-four Nellore × Deccani cross ram lambs aged about 3 months (average body wt. 10.62 ± 0.03 kg) were randomly allotted into four groups fed with CR-I (60R:40C), CR-II (50R:50C), CR-III (40R:60C), and CR-IV (30R:70C) complete diets. The roughage to concentrate ratio did not affect the dry matter intake (in grams/day or grams/kilogram weight(0.75)). The crude protein (P < 0.01) and ether extract (P < 0.05) digestibility of ration CR-IV was higher than CR-I and CR-II rations, whereas, the digestibility of nitrogen-free extract and fiber fractions was similar among all the rations. Experimental diets were different (P < 0.01) in digestible crude protein (DCP) content, in which the CR-I ration contained lower DCP value whereas CR-IV ration contained higher DCP value. The total digestible nutrients (TDN) and metabolizable energy (ME) values were comparable among all the experimental rations. The daily DCP intake (in grams/day) was lower (P < 0.05) in lambs fed with CR-I ration compared to CR-III and CR-IV rations and it was comparable with CR-II ration. The TDN intake (in grams/day), digestible energy, and ME intakes (in megajoules/day) were similar among the lambs fed experimental rations with different SSB to concentrate ratios. The average daily DCP intake of lambs fed with CR-II, CR-III, and CR-IV rations met the requirements whereas, the daily TDN and ME intake was met by all the lambs. The lambs on all the diets were in positive nitrogen retention. The nitrogen balance expressed as grams/day was higher (P < 0.05) in lambs fed with CR-III and CR-IV ration than those fed with CR-I ration. The daily calcium and phosphorus intake and balance were comparable on all the experimental rations. The total purine derivatives (in millimoles/day) were higher (P < 0.05) in CR-III than CR-I and comparable with CR-II and CR-IV diets. The higher (P < 0.01) microbial N supply (in grams/day) was observed in CR-III ration compared to other three rations and the efficiency of microbial synthesis was comparable among all the rations. It is concluded that sweet sorghum bagasse can be included in the complete rations at maximum level of 50 % as roughage source for rearing of ram lambs.

Fattening performance, carcass and meat quality characteristics of Kivircik male lambs

The objective of this study was to determine the fattening performance and carcass and meat quality characteristics of Kivircik twin male lambs. Twelve lambs at approximately 5 months of age were subjected to a finishing diet for 60 days. Average live weight of lambs at the beginning and the end of the fattening were 23.14 ± 0.84 and 39.0 ± 1.01 kg, respectively. Daily live weight gain and feed conversion efficiency were found as 0.265 ± 0.007 and 6.14 kg, respectively. Hot carcass weight, cold carcass weight, and dressing percentage were 19.6 ± 0.6 and 18.9 ± 0.6 kg and 48.1 ± 0.3%, respectively. Kidney-pelvic fat weight, internal fat weight, and m. longissimus dorsi area were 0.117 ± 0.023 and 0.364 ± 0.041 kg and 15.26 ± 0.70 cm(2), respectively. The percentages of leg, back loin, forearm, shoulder, neck, flank-chest, kidney-pelvic fat, and internal fat in carcasses of the lambs were found as 34.1 ± 0.4%, 19.6 ± 0.3%, 21.0 ± 0.2%, 7.0 ± 0.3%, 10.5 ± 0.3%, 7.2 ± 0.2%, 1.3 ± 0.1%, and 1.8 ± 0.1%, respectively. Averages water content, ash, protein content, and fat content of meat samples were 73.4%, 1.0%, 19.5% and 3.6%, respectively. pH and thiobarbituric acid reactive substances values of meat samples were 5.55 and 0.056 ± 0.017. L*(lightness), a*(redness), and b*(yellowness) values were recorded as 43.87, 12.69, and 10.22, respectively. Thus, we conclude that fattening performance, carcass, and meat quality of Kivircik lambs are satisfactory levels than that of other native breeds.

Developmental changes in hypothalamic Kiss1 expression during activation of the pulsatile release of luteinising hormone in maturing ewe lambs

Onset of puberty is characterised by a marked increase in the frequency of release of gonadotrophin-releasing hormone (GnRH) and luteinising hormone (LH). The Kiss1 gene plays a critical role in pubertal development, and its product, kisspeptin, stimulates GnRH and LH release. In the present study, we tested the hypothesis that Kiss1 gene expression in the preoptic area (POA) and hypothalamus increases during maturation of the reproductive neuroendocrine axis in association with increased LH pulsatility. Ovariectomised, oestradiol-replaced lambs were euthanised at 25, 30 and 35 weeks of age. Blood samples were collected before euthanasia to characterise the pattern of LH release. Kiss1 mRNA was detected in coronal sections of the POA and hypothalamus and Kiss1-expressing cells were identified on the basis of silver grain density. The mean number of Kiss1-expressing cells in the POA/periventricular (PeV) areas increased from 25 to 30 weeks of age. No further increase at 35 weeks of age was observed, and the changes in Kiss1 expression in the POA/PeV were independent of changes in LH pulse frequency. The mean number of Kiss1-expressing cells in the arcuate (ARC) nucleus did not differ among age groups, although it was greater in the middle ARC of lambs exhibiting increased frequency of LH release. The density of silver grains per cell did not differ among groups in any of the areas studied. The results obtained indicate that the Kiss1 gene is activated in the POA/PeV and ARC of ewe lambs during juvenile development, and that kisspeptin neurones in the middle ARC, in particular, are involved in the acceleration of pulsatile LH release during maturation of the reproductive neuroendocrine axis in ewe lambs.

Alternative feedstuffs and their effects on performance of Awassi sheep: a review

Fat-tailed sheep (FTS) is a group of breeds characterized by large (fatty) tails that it is commonly distributed in Africa, Middle East, Pakistan, and to a lesser extent in other countries. Awassi, a common FTS breed in many Mediterranean countries, is adaptive and suitable to live in harsh conditions of the arid and semiarid areas. One of the main constraints for sheep industry in those areas is the limited supply and variable quality and quantity of feedstuffs. Using several alternative feedstuffs (AF) has been a common practice to decrease production cost of Awassi sheep industry in those areas. The appropriate AF to be used is determined by several animal and feed factors. These AF includes, but not limited to, unconventional feedstuffs, agricultural byproducts, and agro-industrial byproducts. A good body of literature about the use of AF and the effects of such use on performance of Awassi sheep is available. Some of these AF have been shown to be safely used in Awassi diets with no detrimental effects on sheep performance or health and, thus, recommended to lower the production cost. Other AF has controversial effects and recommendations. This paper reviews the effects of using AF on performance of Awassi ewes and lambs. Effects on intake, nutrient digestibilities, growth rate, and carcass characteristics of lambs and on intake, nutrient digestibilities, body weight change, milk yield, and milk composition of ewes will be emphasized. Recommendations and limitations for using AF will also be briefly discussed.

A review of some characteristics, socio-economic aspects and utilization of Zulu sheep: implications for conservation

Zulu sheep are Nguni sheep of Zululand and are adapted to the harsh conditions of KwaZulu-Natal. They are used by rural farmers for economic purposes. Their numbers are declining, indicating a potential extinction threat. Knowledge of their phenotypic and genotypic characteristics is essential for conservation planning. In this review, there is a focus on the utilization, socio-economic aspects, phenotypic and genotypic characteristics as well as a proposed breeding programme. A survey has shown that rural farmers in the areas of northern KwaZulu-Natal prefer to keep this breed for its adaptability, resistance to diseases and meat quality. Zulu sheep are small-framed multi-coloured animals. Mature males weigh up to 38 kg and females up to 32 kg. Based on four morphological traits and live weight, phenotypic diversity between three populations was estimated at 48%. A genetic diversity between these three populations was estimated at 22%. Live weight of Zulu sheep can be estimated using the heart girth and wither height measurements. Scrotum circumference of young rams (up to 22 months old) is reliable for estimating the live weight. Animals that were characterized in the studies were grazed extensively and no supplements were provided. There is therefore a potential of weight increase if these animals are reared in a semi-extensive environment. An open nucleus breeding scheme is thus recommended for a sustainable use and conservation of this breed. For more conclusive results, larger numbers of phenotypic and genetic characteristics, in larger numbers of Zulu sheep populations, should be investigated.

Polymorphism of FecB gene in nine sheep breeds or strains and its effects on litter size, lamb growth and development

Nine sheep breeds or strains, including 615 individuals were screened with forced PCR RFLP method for the FecB gene to study the polymorphism and its effects on litter size, body weight and body size. Results showed that the polymorphism frequencies of FecB gene were significantly imbalanced in these breeds or strains. The Hu sheep were all homozygous carriers of FecB gene(BB). In the Chinese Merino prolific meat strain, the genotype frequencies of BB, B+ and ++ were 51%, 30% and 19%, respectively, whereas all the other flocks had only the wild-type (++) genotype. Results within the Chinese Merino prolific meat strain showed that the mean litter size of ewes with genotype BB and B+ were 2.8 (+/-0.74) and 2.3 (+/- 0.63) (P < 0.05), whereas ++ genotype ewes had a litter size of only 1.2 (+/-0.68) (P < 0.01). At day 90 after birth, the body weights of BB/B+ genotype lambs were higher than that of ++ genotype lambs (18.6 +/- 3.70 kg, 18.0 +/- 3.71 kg vs 15.6 +/- 2.22 kg, P < 0.05). In addition, the heart girth and chest width of BB/B+ genotype lambs were significantly longer than those of the ++ lambs (P < 0.05). No significant differences were observed in either body weight or body size at day 120. Litter size at first lambing from Hu at Natural Source Conservative Region was found to be significantly higher than that from the other two regions sampled (P < 0.05). In addition to the additive effect on litter size, these findings showed for the first time that the FecB gene had a positive effect on early postnatal body growth.

The role of sex steroid receptors in sheep female reproductive physiology

Cell responsiveness to steroid hormones is related to the number and affinity of its receptors, thus factors affecting steroid expression will influence tissue sensitivity and functionality. The present review discusses the role of oestrogen and progesterone receptors in sheep female reproductive physiology. The mechanism of steroid hormone action in the target cell is introduced first; the tissue distribution, physiological functions and regulation of oestrogen receptor subtypes and progesterone receptor isoforms in ruminants are reported. The role of steroid receptors in target tissues (with emphasis on the uterus and pituitary gland) during different physiological events is addressed in an attempt to clarify oestrogen and progesterone actions in different developmental and reproductive stages: prepubertal period, oestrous cycle, pregnancy, post-partum period and seasonal anoestrus. The present review shows how the distinct reproductive stages are accompanied by dramatic changes in uterine receptor expression. The role of oestrogen and progesterone receptors in the molecular mechanism responsible for premature luteolysis that results in subnormal luteal function is discussed. Finally, the effect of nutrition on sex steroid receptor expression and the involvement on reproductive performance is reported.

Mechanisms of action of the principal prolific genes and their application to sheep production

The prolificacy variation in sheep makes it an excellent animal model to understand the mechanisms regulating ovulation rate. Identification of mutations responsible for the increased prolificacy of the Inverdale, Booroola, Javanese, Cambridge and Belclare sheep open new avenues of investigation for the paracrine control of folliculogenesis. To date, all known mutations are in genes from ligands or receptors of the transforming growth factor beta superfamily, and point to the bone morphogenetic protein family of peptides as local regulators of ovarian follicle growth. The mechanism of action of the mutated genes is not fully understood, but results in the ovulation of a higher number of follicles with smaller diameter and fewer granulosa cells than that of the wildtype, thus speeding the differentiation of ovulatory follicles. Comparisons of the performance of Booroola-crossed flocks in different countries showed that carriers of the prolificacy mutation have higher ewe productivity but also higher perinatal mortality and lighter weight lambs. Their economic impact on the sheep industry depends on farm environment and management. Nevertheless, the diagnostic tests now available to identify the genetic mutations resulting in increased ovulation rate, will simplify the introduction of these mutations and their monitoring in flocks for research and commercial purposes.

Selective harvesting and habitat loss produce long-term life history changes in a mouflon population

We examined the long-term effects (28 years) of habitat loss and phenotype-based selective harvest on body mass, horn size, and horn shape of mouflon (Ovis gmelini musimon) in southern France. This population has experienced habitat deterioration (loss of 50.8% of open area) since its introduction in 1956 and unrestricted selective hunting of the largest horned males since 1973. Both processes are predicted to lead to a decrease in phenotype quality by decreasing habitat quality and by reducing the reproductive contribution of individuals carrying traits that are targeted by hunters. Body mass and body size of both sexes and horn measurements of males markedly decreased (by 3.4-38.3%) in all age classes from the 1970s. Lamb body mass varied in relation to the spatiotemporal variation of habitat closure within the hunting-free reserve, suggesting that habitat closure explains part of these changes. However, the fact that there was no significant spatial variation in body mass in the early part of the study, when a decline in phenotypic quality already had occurred, provided support for the influence of selective harvesting. We also found that the allometric relationship between horn breadth and horn length changed over the study period. For a given horn length, horn breadth was lower during the second part of the study. This result, as well as changes in horn curve diameter, supports the interpretation that selective harvesting of males based on their horn configuration had evolutionary consequences for horn shape, since this phenotypic trait is less likely to be affected by changes in habitat characteristics. Moreover, males required more time (approximately four years) to develop a desirable trophy, suggesting that trophy hunting favors the reproductive contribution of animals with slow-growing horns. Managers should exploit hunters' desire for trophy males to finance management strategies which ensure a balance between the population and its environment. However, for long-term sustainable exploitation, harvest strategy should also ensure that selectively targeted males are allowed to contribute genetically to the next generations.