Effects of maternal calcium propionate supplementation on offspring productivity and meat metabolomic profile in sheep

This study determined the effect of dietary calcium propionate (CaPr) as a source of energy supplementation during the First Half of Gestation (FMG), the Second Half of Gestation (SMG), and during All Gestation (AG), on offspring post-weaning growth performance, meat quality, and meat metabolomic profile. Thirty-one pregnant ewes were assigned to one of four treatments: a) supplementation of 30 gd-1 of CaPr during the first half of gestation (day 1 to day 75, n = 8) (FMG); b) supplementation of 30 gd-1 of CaPr during the second half of gestation (day 76 to day 150, n = 8) (SMG); c) supplementation of 30 gd-1 of CaPr during all gestation (AG, n = 8); d) no CaPr supplementation (control; CS, n = 7). The ewes were ad libitum fed a basal diet based on oat hay and corn silage. Ewes were distributed in a completely randomized unbalanced design to four treatments. The FMG group had lower (P ≤ 0.05) birth weight and weaning weight than the CS group. However, the average daily gain was similar across all treatments. Empty body weight and FMG had lower values (P ≤ 0.05) than the other groups. Both FMG and AG had lower hot carcass weight (P ≤ 0.05) compared to CS, while CaPr treatments resulted in reduced hot carcass yield (P ≤ 0.05). Meat color and texture were similar among treatments. A principal component analysis between gestation stages showed a trend for separating CS and FMG from SMG and AG, and that was explained by 93.7% of the data variability (PC1 = 87.9% and PC2 = 5.8%). Regarding meat metabolomic profile, 23 compounds were positively correlated between all treatments. Only 2 were negatively correlated (eicosane and naphthalene 1,2,3); but tetradecanoic acid, hexadecane, undecane 5-methyl, (-)-alpha, hexadecenoic acid, octadecanoic acid, and octadecane had a highly significant correlation (P ≤ 0.05). Overall, dam supplementation with CaPr during different periods of gestation provoked changes in meat metabolites related to the biosynthesis of fatty acids in lambs without negative changes in lamb's growth performance and carcass quality.

Effects of Birth Weight on Animal Performance, Fattening Traits and Meat Quality of Lambs

Simple Summary

It is accepted that a low body weight at birth (<4 kg) might impair postnatal muscle and increase adipose tissue development during the whole life of lambs. Therefore, in the present study, we aimed to evaluate the effect of body weight at birth of lambs on the growth performance, ruminal parameters, digestibility, non-carcass components, carcass traits, physicochemical characteristics and fatty acid profile of meat when slaughtered at 27 kg. Compared to the lambs born with a high weight (>5.5 kg), the lambs born with a low body weight showed a worse animal performance during the fattening period, and increased fat depots with a higher content of saturated fatty acids and a reduced tenderness of meat.

Abstract

Intrauterine growth restriction (IUGR) is a key developmental programming factor which might impair both the feed efficiency of lambs and meat quality, since it deeply impacts skeletal muscle and adipose tissue development. To determine the effect of birth weight on the growth performance, ruminal parameters, digestibility, non-carcass components, carcass traits, physicochemical characteristics and fatty acid profile of meat, two experimental groups (six animals in each group) of male Merino lambs with different body weights (BW) at birth (low BW (LW; 3.88 ± 0.281 kg) and high BW (HW; 5.80 ± 0.647 kg)) were used. The lambs were penned with their corresponding ewe during the natural suckling period, being weaned at 15 kg. Then, the lambs were penned individually and offered a complete pelleted diet during the fattening period. All the animals were slaughtered when they reached 27 kg of BW. After weaning, both daily dry matter intake (578 vs. 615 g/day; p = 0.021) and average daily gain (141 vs. 190 g/day; p = 0.004) were significantly lower in LW lambs, and a higher feed:gain ratio was recorded for this group (3.98 vs. 3.45; p = 0.008). Carcass traits did not show differences (p > 0.05) between both groups of lambs, except for higher chilling losses for the LW group (3.29 vs. 2.69%; p = 0.012). Additionally, higher amounts of kidney knob and channel fat were observed for LW lambs (85.4 vs. 152 g; p = 0.028). Apart from a higher hardness of meat in LW lambs (152 vs. 189 Newtons, p = 0.040), no other differences (p > 0.05) were observed in the physicochemical traits of this product; however, the meat of LW lambs tended (p = 0.057) to contain more total fatty acid content with a higher (p = 0.041) proportion of saturated fatty acids than the meat of HW lambs. In conclusion, under the conditions of the present study, a low body weight at birth increased the deposition of fat in carcass and non-carcass components during the fattening period of lambs, thus reducing animal performance and worsening the nutritional indexes of the meat. Accordingly, it seems reasonable to try to identify these animals during early life, to be sold as suckling lambs in the meat market instead of being fattened.

Relationships between prenatal ewe traits, milk production, and preweaning performance of twin lambs

There is limited information on factors affecting twin lamb growth before weaning, which limits the options available to farmers to actively manage lamb growth. Data from 2 multiyear experiments involving 402 twin-bearing Romney ewes were used to evaluate the effects of prenatal ewe traits (live weight at mating and set stocking and BCS at mating and set stocking) and combined twin lamb birth weight on ewe milk production and lamb growth from birth to weaning as well as the proportion of variation in twin lamb growth that could be explained by these variables. Additionally, the effect of accumulated ewe milk yield over a 42-d period (MY; Days 0 to 42) and accumulated milk components (protein, fat, and lactose) on twin lamb growth were investigated. The effects of prenatal variables on MY, birth weight, and combined twin lamb live weight gain from Day 0 to 42 (LWG) were inconsistent across the 2 experiments. In addition, prenatal ewe traits ( < 0.05) explained less than 30% of the variation in MY and lamb growth from birth to weaning in both experiments. Combined twin lamb birth weight was positively ( < 0.001) correlated with MY ( = 0.34 and = 0.43 in Exp. 1 and 2, respectively). Combined twin lamb LWG was dependent on ewe MY ( = 0.43 for Exp. 1 and = 0.30 for Exp. 2). Lactose, fat, and milk CP yields explained 47 and 42% of the variation in lamb LWG in Exp. 1 and 2, respectively. Lactose and milk CP yield positively affected ( < 0.05) LWG in Exp. 1 and 2, respectively. Fat yield had a positive relationship with LWG in Exp. 1 and a negative relationship with LWG in Exp. 2. In conclusion, the measured prenatal ewe traits had a minimal effect on milk yield and twin lamb growth to weaning. Milk yield and composition explained the greatest proportion of variation in LWG. This suggests that farmers should select ewes with higher milk yields to maximize twin lamb growth to weaning. However, less than 50% of the variation in LWG and weaning live weight was explained by the measured ewe and lamb parameters. Therefore, further studies are required to determine additional ewe or lamb variables that control variation in twin lamb growth.

Invited review: impact of specific nutrient interventions during mid-to-late gestation on physiological traits important for survival of multiple-born lambs

To improve production efficiency, the sheep meat industry has increased flock prolificacy. However, multiple-born lambs have lower birth weights, increased mortality and reduced growth rate compared with single-born lambs. Lamb mortality is a major issue for livestock farming globally and solutions are required to increase survival to realise the value of increased flock fecundity. Nutrition during gestation can influence maternal-foetal placental nutrient transfer and thus foetal growth and organ/tissue development, as well as improve postnatal productivity. This review covers the challenges and opportunities associated with increased prolificacy, highlights gaps in our knowledge and identifies some opportunities for how targeted intervention with specific nutrients during mid-to-late pregnancy may influence lamb survival and productivity with a specific focus on pasture-based systems. This time frame was selected as intervention strategies in short-time windows post-pregnancy scanning and before lambing to improve lamb survival in high-risk groups (e.g. triplets) are likely to be the most practical and economically feasible options for pasture-based extensive farming systems.

Maternal insulin sensitivity in midpregnancy does not determine birth weight after embryo transfer between large and small breed sheep

Embryo transfer of large sheep breed embryos (Suffolk) into small breed ewes (Cheviot) constrains birth size, but the maternal factors influencing fetal growth restriction are unknown. We hypothesized that reciprocal embryo transfer crosses between breeds of divergent size would affect pregnancy-related development of maternal insulin resistance in midgestation, thereby influencing fetal growth. Following superovulation, embryos were surgically collected 6 d postmating and transferred to recipients on the same day. Between- and within-breed transfers were performed. Between 60 and 70 d of pregnancy overnight-fasted ewes underwent hyperinsulinemic-euglycemic clamps for assessment of insulin sensitivity. Maternal insulin sensitivity did not vary with transferred lamb breed. Overall, Cheviot ewes tended to have higher fasting glucose (P = 0.068), fasting insulin (P = 0.052), and steady-state glucose (P = 0.065) concentrations than Suffolk ewes at the stage of pregnancy studied. As expected, transferred between-breed Suffolk lambs were born lighter (P = 0.014), and transferred between-breed Cheviot lambs tended to be heavier at birth (P = 0.056) than respective lambs transferred within breed. Midgestation insulin sensitivity does not appear to be a major factor constraining growth of large breed sheep fetus transferred into smaller breed or a factor in releasing constraint in growth of a small breed fetus within a larger breed ewe. However, as embryo size is already different between transferred groups by 19 d, factors other than maternal gestational insulin resistance may determine fetal growth in this embryo transfer paradigm.

Intensive sheep and beef production from pasture--a New Zealand perspective of concerns, opportunities and challenges

This paper details current production trends for sheep and beef cattle production in New Zealand and gives some insight into the opportunities for improvement based on New Zealand research at Massey University. Further it outlines some of the challenges the industries face in the near future. The New Zealand climate favours pasture growth and this is the key to sheep and beef cattle production with over 95% of the diet being grazed pasture or crop. Exports are the focus of the industry with 95% of sheep meat and wool, and 80% of beef exported. There have been considerable gains in production over the last 20 years but there still remains a huge opportunity for further intensification through breeding sheep at an earlier age, increasing the weight of lambs weaned per ewe per year and improving beef production systems. These improvements need to occur within a framework of minimal environmental footprint and produce products that are in demand in the high end international markets.

Response of additional ewe lamb liveweight during gestation on birth and weaning weight of offspring and liveweight of the ewe lamb at weaning

Increasing the liveweight of ewe lambs during gestation may have positive effects on lamb birthweight and weaning weight and also on ewe lamb liveweight at weaning. Specific times during the gestation period of the ewe lamb may be more responsive to improved nutrition and increases in liveweight. The objective of this work was to use a meta-analytic approach to investigate the effects of ewe lamb liveweight at mating and during pregnancy on lamb birth and weaning weights, and the ewe lamb’s liveweight at weaning. Increasing ewe lamb liveweight in early gestation and in particular before mating gave the greatest increases in the birth and weaning weight of the lambs, and also of the ewe lamb’s liveweight at weaning compared with increasing liveweight in the second and third trimester of gestation. This indicates that management practices for ewe lambs that generate higher liveweight at mating are likely to result in increased lamb survival, higher weaning percentages, greater lamb weaning weights and create rising 2-year-old ewes with better liveweight for mating in the subsequent season. Compared with ewe lambs that gave birth and reared singletons to weaning, those ewe lambs that gave birth to twins and reared twins had greater increases in lamb birthweights, lamb weaning weights and ewe lamb weights at weaning for each extra kilogram of ewe lamb liveweight during gestation. For ewe lambs, especially those that birth and rear twins, management options that increase the pre-mating weights will have the greatest response in lamb birthweight, weaning weight and liveweight of the ewe lamb itself at weaning.

Does the physiological status of lambs within a twin- and triplet-born litter differ during the first 12 hours of life?

This study examined the physical and physiological differences from birth until 12 h of age within twin- and triplet-born litters. In 2005 and 2006, the parturition of 75 twin- and 62 triplet-bearing Romney ewes were observed. After parturition lamb blood samples were taken within 5 min of birth and rectal temperature was measured within 5 min of birth and at 1, 3, 6 and 12 h post-birth. Lamb birth weight, crown–rump length and thoracic-girth circumference were measured at 3 h of age. Lamb birth weight, plasma glucose, fructose, lactate, thyroxine and tri-iodothyronine did not differ (P > 0.05) between the heaviest-twin-born, lightest-twin-born and heaviest-triplet-born lamb. The lightest-triplet-born lambs, however, had lighter (P < 0.001) birthweights, greater (P < 0.001) surface-area-to-birth weight ratio, lower (P < 0.05) rectal temperatures, greater (P < 0.1) lactate concentrations and lower (P < 0.1) plasma thyroid hormone concentrations. These characteristics are known to have a negative impact on the ability of the lamb to maintain its body temperature after birth and may therefore provide some evidence as to why triplet-born lambs display a greater mortality rate than twin-born lambs, and why the lightest-triplet-born lambs have the greatest mortality rate within a litter.

Effect of offering concentrate supplement in late pregnancy, under conditions of unrestricted herbage, on the performance of multiple-bearing ewes and their lambs to weaning

The aim of the present study was to determine if offering ewes a commercial concentrate supplement under conditions of unrestricted perennial ryegrass–white clover herbage availability would increase newborn lamb heat production, colostrum intake and subsequent liveweight. Forty seven twin- and 43 triplet-bearing Romney composite ewes (1/2 Romney, 1/4 Finn, 1/4 Texel) were randomly allocated to either non-concentrate or concentrate treatment groups (twin non-concentrate, n = 24; twin concentrate, n = 23; triplet non-concentrate, n = 22; triplet concentrate, n = 21) from Day 79 of pregnancy. Concentrate-fed ewes were offered an increasing amount of concentrate sheep pellets from Day 79 until Day 90 of pregnancy, at which stage ewes were offered 400 g/day per ewe until they lambed. Pre- and post-grazing herbage masses did not differ (P > 0.05) between non-concentrate (2162 ± 54 and 1704 ± 47 kg DM/ha) and concentrate (2135 ± 49 and 1771 ± 42 kg DM/ha) ewes. Ewe nutritional treatment had no effect (P > 0.05) on ewe liveweight, body condition score, β-hydroxybutyate or non-esterified fatty acid concentrations in late pregnancy. Offering concentrates increased (P < 0.05) the birthweight of triplet-born lambs (4.4 ± 0.1 v. 3.9 ± 0.1 kg for those born to concentrate and non-concentrate ewes, respectively) but had the opposite effect on twins (4.8 ± 0.1 v. 5.2 ± 0.1 kg, respectively). There was no difference (P > 0.05) in maximal heat production, total heat production, rate to reach maximal heat production, and IgG concentrations at 24–36 h of age or liveweight and survival of lambs born to ewes offered concentrates or not. Twin-born lambs had greater (P < 0.05) liveweight and total heat production and had higher (P < 0.05) survival rates than triplet-born lambs. In conclusion, the results of the present study indicate that there are only minor beneficial effects from offering concentrate supplements to ewes in late pregnancy under conditions of unrestricted herbage availability and it is not a viable option for farmers to utilise.

Effect of birthweight and birth rank on the survival of single and twin lambs born to ewe lambs

Benefits of ewe lamb mating include improved lifetime production, increased rates of genetic gain and higher net profits. These benefits are only achieved if the ewe lamb successfully rears its offspring to weaning. A meta-analytic approach was used to assess the effects of birthweight and the interacting effect of birth rank on the survival to weaning of lambs born to ewe lambs. The data were from eight studies where birthweight and weight at weaning had been recorded for lambs born from ewe lambs. Data were for single- (n = 1392) or twin-born lambs (n = 456). The twin lambs were further classified as the ‘heavier’ or ‘lighter’ of the pair to give three birth rank categories. To compare the probability of dying before weaning between birth ranks, but with lambs compared at a similar birthweight, lambs were categorised by their birthweight as heavy (>3.8 kg) or light (<3.8 kg) and also categorised within their birth rank on their placement around the mean birthweight (birthweight deviation). A mid-range birthweight deviation fell between one standard deviation above or below the mean for each birth rank, whereas a low- and high-range birthweight fell below and above the mid-range, respectively. Logistic regression was used to assess the effect of birth rank (single, heavier twin and lighter twin) and birthweight on lamb mortality up to weaning. To compare the probability of surviving up to weaning between the different birth ranks, relative risk ratios were calculated. Birth ranks were compared for lambs within the same birthweight group (heavy or light) and same birthweight deviation (low-, mid-, high-range). Decreasing birthweight increased mortality before weaning in twins and the change in mortality was greater for the lighter twin. Birthweight did not alter mortality before weaning in singles. Comparison of the birth ranks showed that there were differences (P < 0.05) in the probability of dying for lambs of different birth ranks but similar birthweight. The results suggest that management options for ewe lambs that increase the birthweight of the lighter twin could increase the weaning percentage.