Performance of dairy cattle fed citrus pulp or corn products as sources of neutral detergent-soluble carbohydrates

Effect of biological lignin depolymerization on rice straw enzymatic hydrolysis, anerobic fermentation characteristics and in vitro ruminal digestibility

This study investigated the effects of lignin depolymerization using laccase on rice straw silage fermentation characteristics, lignocellulose biodegradation and in vitro digestibility. Rice straw was ensiled for 120 days, either without additives (control), or pretreated with Lactobacillus plantarum and cellulases (LPC), cellulases and laccase (CL), and L. plantarum, cellulases and laccase (LPCL). The results revealed that LPC and LPCL treated silages exhibited significantly lower (P < 0.05) pH values, higher (P < 0.05) lactic acid content (24.76 and 27.02 g/kg dry matter (DM)) and significantly higher water-soluble carbohydrate content (20.12 and 22.46 g/kg DM) compared to control and CL treated silages. Laccase-containing treatments (CL, LPCL) significantly reduced lignin, cellulose and hemicellulose contents in the ensiled rice straw compared to the control and LPC treated silages. Structural alterations in the straw, induced by pretreatments, were confirmed by Fourier Transform Infrared spectroscopy, Scanning Electron Microscope and X-ray diffraction analysis. The CL treated silage exhibited the lowest (P < 0.05) in vitro digestibility, while the LPCL treated silage had the highest in vitro total gas production (25.50 mL). In conclusion, laccase effectively degraded lignin during ensiling, and the combined application of laccase with L. plantarum and cellulases enhanced both the enzymatic hydrolysis and ensiling quality of rice straw. These findings demonstrate the potential of biological lignin depolymerization during ensiling as an innovative strategy to significantly enhance the nutritional value of straw bioresources, paving the way for sustainable livestock production and waste reutilization.

Effect of ensiled alpha-amylase-enabled corn grain at 2 concentrations in the diet on lactation performance, chewing activity, ruminal fermentation, nutrient digestibility, and nitrogen partition of dairy cows

This experiment evaluated the effect of α-amylase-enabled corn (AAC) on cows fed ensiled mature kernels at 2 concentrations in the diet. Twenty individually housed Holstein cows, arranged in 4 × 4 Latin squares (with 21-d periods), were exposed to each of 4 treatments in a 2 × 2 factorial combination of corn concentration (C): high corn concentration (High; 28.7% starch, 24.6% corn, 2.5% citrus pulp) versus low corn concentration (Low; 21.5% starch, 14.1% corn, 13.8% citrus pulp) and type (T): AAC (48.8% vitreousness) versus isogenic control (CTL; 51.1% vitreousness). Kernels were ground weekly, hydrated (62.2 ± 1.3% DM on AAC and 63.1 ± 1.4% DM on CTL), and ensiled for 28 ± 3 d. The statistical model had the effects of square, cow (square), period, C, T, and the C × T interaction. No effect of treatment was detected for milk yield (34.1 kg/d) and DMI (22.8 kg/d). High corn reduced the daily yield of fat (1.209 kg/d vs. 1.297 kg/d) and ECM (33.2 kg/d vs. 34.4 kg/d) and increased milk protein concentration (3.12% vs. 3.09%). When fed with Low, AAC increased ECM/DMI relative to CTL (1.54 vs. 1.49). Meal frequency was reduced on High-AAC (9.8 meals/d) relative to Low-AAC (10.3 meals/d). Cows fed High had greater proportion of daily intake in the morning (49.9% vs. 44.4%) and longer duration of the first daily meal (69.7 min vs. 62.0 min) than cows fed Low. There was a tendency for AAC to increase the total-tract NDF digestibility (49.9% vs. 48.0%), but starch digestibility did not differ (98.4%). Ruminal microbial yield did not differ (335 mmol/d of allantoin in urine). High reduced the ruminal acetate to propionate ratio (2.45 vs. 2.95) and pH (6.59 vs. 6.74) relative to Low. Cows fed High-AAC had lower MUN than Low-AAC (17.4 mg/dL vs. 18.8 mg/dL), and plasma urea-N was lower on High-AAC than on High-CTL and Low-AAC (17.2, 19.0, and 18.7 mg/dL, respectively). High starch reduced urine-N excretion (g/d) and partition (% of daily N intake) relative to Low starch and also tended to reduce fecal-N excretion and partition. Overall, Low starch increased milk solids yield, N loss in urine and feces, and the ruminal acetate to propionate ratio. Cows fed AAC and Low had the highest feed efficiency, and cows fed AAC and High had the lowest proportion of N intake in total excreta.

The impact of citrus pulp inclusion on milk performance of dairy cows: A meta-analysis

Considering sustainability and circular economy, citrus pulp could become a common dairy feedstuff. Yet, there is no clear indication of the amount of citrus pulp that can be fed without compromising milk performance or that could deliver benefits. In our meta-analysis, we investigated the impact of varying citrus pulp inclusion levels, i.e., no (0 %), low (>0-10 %), medium (>10-20 %), and high (>20 %), on milk performance variables. Replacing cereal grains with citrus pulp increased pectins and sugars while decreasing starch. At the low inclusion level, citrus pulp increased milk yield without affecting feed intake. At higher inclusion levels, citrus pulp reduced feed intake and milk yield but with higher fat contents, the milk energy content was similar to no inclusion. Concluding, citrus pulp is a good energy source with lipogenic properties in dairy cows. We encourage research to fill in the existing gap of knowledge at the rumen and systemic levels.

Evaluation of different ratios of neutral detergent-soluble carbohydrate fractions on performance, ingestive behavior, and nitrogen balance in dairy goats

Cell components soluble in neutral detergent are a diverse group, both compositionally and nutritionally. The present study aimed to evaluate production responses, behavior (eating, ruminating, and idling), and nitrogen balance of dairy goats fed different ratios of neutral detergent-soluble carbohydrate fractions. Five multiparous Alpine does with mean ± SD initial body mass of 49.5 ± 7.9 kg and 60 days of lactation were randomly assigned in a 5 × 5 Latin square design. The treatments were the ratios of starch (starch associated with soluble sugar [StSS]) to neutral detergent-soluble fiber (NDSF) (StSS:NDSF): 0.89, 1.05, 1.24, 1.73, and 2.92. No effect was observed (P > 0.05) of StSS:NDSF on the intakes of neutral detergent fiber (NDF) and NDSC. However, DM intake showed a quadratic behavior (P = 0.049). The ingestive behavior was affected by StSS:NDSF linearly increased (P = 0.002) the feeding efficiency. The increase in StSS:NDSF caused a linear increase in fecal (P = 0.011), urinary (P < 0.001), and milk nitrogen excretion (P = 0.024). The increase in StSS:NDSF affected (P = 0.048) milk yield and net energy lactation (P = 0.036). In conclusion, dairy goats experience reduced dry matter intake and milk yield when subjected to high-NDSC diets, specifically those above 1.24 StSS:NDSF ratio. Elevated NDSC levels in the diets lead to decreased feeding time, whereas rumination remains unaffected. Nitrogen losses in goats increase linearly with high-NDSC diets, and a significant impact on nitrogen balance.

Intake, Digestibility, Ruminal Fermentation, and In Situ Disappearance of Bermudagrass Hay by Lactating Beef Cows Offered Corn or Hominy Feed as Supplements at Two Different Rates

Hominy feed (HF) has been evaluated in feedlot and dairy rations but has not been evaluated as a supplemental energy source for lactating beef cows. The objective of this study was to determine the effect of level of HF supplementation on intake, digestibility, ruminal fermentation characteristics, and in situ dry matter (DM) disappearance of bermudagrass hay. Five ruminally cannulated lactating beef cows (body weight (BW) = 596 kg, SE = 13.9) were used in an experiment with a 5 × 5 Latin square design. Treatments were a bermudagrass hay-basal diet with low HF (LH; 0.25% BW), medium HF (MH; 0.50% BW), low ground corn (LC; 0.25% BW), medium ground corn (MC; 0.50% BW) and no supplement (CON). Cows were housed individually, and supplements were offered at 0800 daily. Hay was offered to maintain 10% refusal. Periods were 16-d, with 10 d for adaptation. Ruminal fluid was sampled on d 14 of each period for measurement of pH, volatile fatty acids, and rumen ammonia-N. An in situ degradation experiment for bermudagrass hay was completed for each diet. Hay dry-matter intake (DMI % BW) was not affected (p = 0.14) by supplement, but total DMI (DMI % BW) was greater (p ≤ 0.05) in MH and MC compared to LH and CON. Digestible DMI % BW was greater (p = 0.05) in MH compared to LC, MC was intermediate, and LH and CON were lesser (p ≤ 0.01) than all other diets. Dry-matter fill, passage rate, and retention time did not differ by diet (p ≥ 0.31). A diet × time interaction was observed for ammonia-N (p = 0.0002), and propionate (p = 0.02) time effects were observed for other parameters, but no diet effects. Bermudagrass hay's potentially degradable fraction was greater (p ≤ 0.05) in LH than MH and CON, but effective DM degradability was not different (p = 0.39) among diets. Overall, no diets reduced hay intake or disappearance compared to CON; therefore, no negative associative effects were observed from any of the supplements at the levels offered in this study.

Effects of a hepatoprotectant and different feed energy sources on milk composition and nutrient partitioning in lactating cows

ABSTRACT The present study aimed at assessing the effects of hepatoprotective agents in diets that contain sources of energy on milk production, milk composition, and nutrient partition in lactating cows. Sixteen Holstein x Gir crossbred mid-lactation cows with an average body weight of 553 ± 85 kg were used in this study. These animals were allocated in a 4x4 Latin square design. A 2x2 factorial arrangement was employed in this feeding experiment. In each treatment, cows received diets with or without a hepatoprotective agent and variable in ground corn grain or citrus pulp as energy sources. Evaluated parameters included nutrient intake and digestibility, milk production, milk composition, energy balance, and nitrogen balance. Performance and nutrient balance variables were assessed and no interaction was observed between the hepatoprotective compounds and the dietary sources of energy. Dry matter intake, milk production and net energy for lactation were higher in corn as an energy source whereas milk fat content was higher in citrus pulp diets. There was a reduction in protein and casein contents in the milk of cows that was supplemented with an hepatoprotective agent. In this study, the hepatoprotective agent improved nitrogen balance in dairy cows. The use of the hepatoprotective compounds in the diet of these lactating cows in confinement reduced the milk protein fraction and favored a higher nitrogen balance in these animals. Retention of nitrogen compounds in the metabolism of lactating cows under confinement is influenced by hepatoprotective agents.

A Combination of Lactic Acid Bacteria and Molasses Improves Fermentation Quality, Chemical Composition, Physicochemical Structure, in vitro Degradability and Rumen Microbiota Colonization of Rice Straw

Aims

This study aims to evaluate the effect of lactic acid bacteria (LAB) and LAB-molasses (LAB + M) combination on the fermentation quality, chemical composition, physicochemical properties, in vitro degradability of rice straw and the characteristics of rumen microbial colonization on rice straw surface.

Methods and Results

There were three pretreatments, including control (not treated, Con), treated with LAB, or LAB + M. The results showed that both LAB and LAB + M treatments altered the physical and chemical structures of rice straw and were revealed by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) spectroscopy, respectively. Moreover, both LAB and LAB + M pretreated rice straw increased the crude protein (CP) content, dry matter (DM) recovery, and in vitro digestibility and decreased the pH value, neutral detergent fiber (NDF), and acid detergent fiber (ADF) contents. The LAB + M pretreated rice straw increased the gas production (GP72) and rumen microbial colonization on the rice straw surface.

Conclusions

It is observed that LAB + M treatment could increase digestibility and the rumen microbial colonization on the rice straw surface. Therefore, LAB + M treatment can provide an alternative strategy to improve the quality of rice straw. Significance and impact of the study: This study provides an optimal pretreatment to improve the rice straw digestibility and rumen microbial colonization.

Effects of different moist orange pulp inclusions in the corn grain rehydration for silage production on chemical composition, fermentation, aerobic stability, microbiological profile, and losses

This study evaluated the effects of different moist orange pulp (MOP) inclusions in corn grain rehydration for silage production as a strategy to store and use MOP and whether these inclusions result in adequate fermentation and aerobic stability (AE) and acceptable losses. Ground corn grain and MOP were weighed separately and mixed to obtain MOP inclusions of 21%, 34%, or 42%. The control treatment was obtained with corn rehydrated with distilled water and MOP inclusion of 0%, with five laboratory silos (15-L buckets) per treatment. Acid detergent fiber, acid detergent insoluble protein, acid detergent lignin, lactic acid, acetic acid, and ethanol contents increased linearly with increasing MOP inclusion, whereas starch, in vitro dry matter (DM) digestibility and butyric acid contents and pH decreased linearly. NH₃ -N/TN content reduced quadratically and was minimal with 8.34 g/kg DM at 14% MOP inclusion. Total DM losses increased quadratically with maximal losses of 4.26% DM at 25% MOP inclusion. AE reduced by 2.8 h for each 1% increase in MOP inclusion. Rehydration of corn grain with MOP results in an adequate fermentation process. The inclusion of 34% MOP was the best because DM losses were lower and AE was not drastically reduced.

Brittle Culm 15 mutation alters carbohydrate composition, degradation and methanogenesis of rice straw during in vitro ruminal fermentation

Brittle Culm 15 (BC15) gene encodes a membrane-associated chitinase-like protein that participates in cellulose synthesis, and BC15 gene mutation affects cell wall composition in plant, such as cellulose or hemicellulose. The present study was designed to investigate the changes of carbohydrates composition in bc15 mutant straw, and the resulting consequence on rumen fermentation, methanogenesis, and microbial populations (qPCR) during in vitro ruminal fermentation process. Two substrates, bc15 mutant and wild-type (WT) rice straws, were selected for in vitro rumen batch culture. The first experiment was designed to investigate the kinetics of total gas and CH₄ production through 48-h in vitro ruminal fermentation, while the second experiment selected incubation time of 12 and 48 h to represent the early and late stage of in vitro ruminal incubation, respectively, and then investigated changes in biodegradation, fermentation end products, and selected representative microbial populations. The bc15 mutant straw had lower contents of cellulose, neutral detergent fiber (NDF) and acid detergent fiber (ADF), and higher contents of water-soluble carbohydrates, neutral detergent solubles (NDS) and monosaccharides. The bc15 mutant straw exhibited a distinct kinetics of 48-h total gas and CH₄ production with faster increases in early incubation when compared with WT straw. The bc15 mutant straw had higher DM degradation, NDF degradation and total volatile fatty acid concentration at 12 h of incubation, and lower NDF degradation and CH₄ production at 48 h of incubation, together with lower acetate to propionate ratio and ADF degradation and higher butyrate molar percentage and NDS degradation at both incubation times. Furthermore, the bc15 mutant straw resulted in greater 16S gene copies of F. succinogenes, with lower 18S gene copies of fungi at both incubation times. These results indicated that the BC15 gene mutation decreased fibrosis of cell wall of rice straw, enhanced degradation at the early stage of rumen fermentation, and shifts fermentation pattern from acetate to propionate and butyrate production, leading to the decreased volume and fractional rate of CH₄ production. However, BC15 gene mutation may enhance hardenability of cell wall structure of rice straw, which is more resistant for microbial colonization with decreased fiber degradation. Thus, this study modified rice straw by manipulating a cell wall biosynthesis gene and provides a potential strategy to alter degradation and CH₄ production during in vitro ruminal fermentation process.

Effects of urea-treated oil palm frond on nutrient composition and in vitro rumen fermentation using goat rumen fluid

Ammoniation of oil palm frond (OPF) with non-protein nitrogen (N) sources has been shown to improve the nutritional value and digestibility of OPF in ruminants. This study evaluated the effect of treating OPF without (control) or with different urea levels (1%-5%) on chemical composition and in vitro gas production, digestibility and fermentation properties using goat rumen fluids. The results showed that the treated OPF with urea (1%-5%) had significantly lower (p < 0.05) dry matter (DM), organic matter (OM) and ash contents than that of the control. The crude protein (CP) content of treated OPF increased (linear p < 0.05; quadratic p < 0.05) with increasing levels of urea inclusion (1%-5%), whereas the contents of neutral detergent fibre (NDF) and acid detergent lignin (ADL) were significantly (p < 0.05) decreased. The CH₄ (ml/500 mg DM incubated) production decreased (linear p < 0.05) with increasing levels of urea inclusion in treated OPF silage. However, in vitro DM and OM degradability were significantly (p < 0.05) increased by higher inclusion levels of urea (4% and 5%). OPF treated with 4% or 5% urea also revealed significantly (p < 0.05) higher total volatile fatty acids and ammonia-N than the control and OPFs treated with 1%-3% urea. Ammoniation of OPF with urea improved its nutritional value and in vitro rumen fermentation profiles in goats. The impact was more pronounced for 4% or 5% urea-treated OPF.

The Effects of Non-Fiber Carbohydrate Content and Forage Type on Rumen Microbiome of Dairy Cows

Simple Summary

For sustainable development in the dairy industry, crop by-products play an important role, especially in areas that lack pasture and are not suitable for intensive cereal-adapted production (i.e., diets containing high amounts of cereal grains). However, feeding crop by-products usually lowers milk production in dairy cows due to their poor nutrient quality. In a previous study, we have demonstrated that non-fiber carbohydrate content (NFC) is a major limiting factor for the utilization of diets based on corn stover (CS). Although the higher abundance of easily fermentable energy in NFC and forage type can influence the synthesis of VFAs and MCP in the rumen and higher NFC content or high quality forages normally have a positive influence on the lactation performance of dairy cows, the underlying microbial mechanisms and potential effects on milk production are under-investigated to date. Here, we examined microbial composition and predicted the metabolism from cows fed CS-based diets with either high levels of NFC (H-NFC), or low levels of NFC (L-NFC). Control cows were fed an alfalfa-based diet (AH). Our results show that, supplementation of the CS-based diet with additional NFC increased amino acid biosynthesis in rumen microbiota in dairy cattle, and thus resulted in better nitrogen conversion. However, lower levels of fibrolytic capacity may limit dry matter intake of cows fed H-NFC and may prevent increased milk yield.

Abstract

The main objective of our current study was evaluating the effects of NFC supplementation and forage type on rumen microbiota and metabolism, by comparing microbial structures and composition among samples collected from cows fed AH (alfalfa-based diet), H-NFC (CS-based diet with high NFC) and L-NFC (CS-based diet with low NFC) diets. Our results show that microbial communities were structurally different but functionally similar among groups. When compared with L-HFC, NFC increased the population of Treponema, Ruminobacter, Selenomonas and Succinimonas that were negatively correlated with ruminal NH3-N, and urea nitrogen in blood, milk and urine, as well as significantly increasing the number of genes involved in amino acid biosynthesis. However, when compared to the AH group, H-NFC showed a higher abundance of bacteria relating to starch degradation and lactate production, but a lower abundance of bacteria utilizing pectin and other soluble fibers. This may lead to a slower proliferation of lignocellulose bacteria, such as Ruminococcus, Marvinbryantia and Syntrophococcus. Lower fibrolytic capacity in the rumen may reduce rumen rotation rate and may limit dry matter intake and milk yield in cows fed H-NFC. The enzyme activity assays further confirmed that cellulase and xylanase activity in AH were significantly higher than H-NFC. In addition, the lower cobalt content in Gramineae plants compared to legumes, might have led to the significantly down-regulated microbial genes involved in vitamin B12 biosynthesis in H-NFC compared to AH. A lower dietary supply with vitamin B12 may restrict the synthesis of milk lactose, one of the key factors influencing milk yield. In conclusion, supplementation of a CS-based diet with additional NFC was beneficial for nitrogen conversion by increasing the activity of amino acid biosynthesis in rumen microbiota in dairy cattle. However, lower levels of fibrolytic capacity may limit dry matter intake of cows fed H-NFC and may prevent increased milk yield.

Potential Valorization of Organic Waste Streams to Valuable Organic Acids through Microbial Conversion: A South African Case Study

The notion of a “biobased economy” in the context of a developing country such as South Africa (SA) necessitates the development of technologies that utilize sustainable feedstocks, have simple and robust operations, are feasible at small scale and produce a variety of valuable bioproducts, thus fitting the biorefinery concept. This case study focuses on the microbial production of higher-value products from selected organic waste streams abundant in the South African agricultural sector using microbes adapted to utilize different parts of biomass waste streams. A ruminant-based carboxylate platform based on mixed or undefined anaerobic co-cultures of rumen microorganisms can convert the carbohydrate polymers in the lignocellulosic part of organic waste streams to carboxylic acids that can be upgraded to biofuels or green chemicals. Furthermore, yeast and fungi can convert the simpler carbohydrates (such as the sugars and malic acid in grape and apple pomace) to ethanol and high-value carboxylic acids, such as lactic, fumaric, succinic and citric acid. This review will discuss the combinational use of the ruminal carboxylate platform and native or recombinant yeasts to valorize biomass waste streams through the production of higher-value organic acids with various applications.

Effects of supplementation of nonforage fiber source in diets with different starch levels on growth performance, rumen fermentation, nutrient digestion, and microbial flora of Hu lambs

The objectives were to evaluate the effects of fiber source and dietary starch level on growth performance, nutrient digestion, rumen parameters, and rumen bacteria in fattening Hu lambs. A total of 360 Hu lambs (BW = 24.72 ± 0.14 kg, 2 months old) were subjected to a 2 × 3 factorial arrangement. Lambs randomly assigned 6 treatments with 6 repetitions (10 lambs per repetition) of each treatment. Six treatments were formulated to include the fiber sources with three starch levels. The experiment lasted a 63 d. The amount of feed, orts, and total feces were sampled on the 42nd day of the experiment. Rumen fluid samples were collected after 2 h of morning feeding on day 56. Rumen contents were collected last day after the selected lambs were slaughtered. Increasing the starch content decreased the digestibility of neutral detergent fiber (NDF, P = 0.005). Increasing the starch level increased the proportions of propionate (P = 0.002) and valerate (P = 0.001) and decreased the proportion of acetate (P < 0.001) and the ratio of acetate to propionate (P = 0.005). The abundance of Fibrobacter succinogenes was affected by an interaction between the fiber source and the starch level (P < 0.001). Fibrobacter succinogenes tended to be greater in lambs fed SH than in lambs fed BP (P = 0.091), which was greater in lambs fed high starch levels than in lambs fed low starch levels (P = 0.014). Increasing the starch level increased Streptococcus bovis abundance (P = 0.029) and decreased total bacteria (P = 0.025). At the genus level, increasing the starch level reduced the abundance of Butyrivibrio_2 (P = 0.020). Nevertheless, the final body weight (BW) and acid detergent fiber (ADF) digestibility were greater (P < 0.01) in lambs fed soybean hull (SH) than in lambs fed BP. The proportion of butyrate was greater (P = 0.005), while the rumen pH was lower (P = 0.001) in lambs fed beet pulp (BP) than in those fed SH. The abundances of Succiniclasticum, Candidatus_Saccharimonas, Ruminococcus_1, and Christensenellaceae_R-7 were greater in lambs fed SH than in those fed BP (P < 0.050), whereas the abundance of Fibrobacter was lower (P = 0.011). The predominant microbial phyla in all of the groups were Firmicutes, Bacteroidetes, and Fibrobacteres. Changing the starch level for fiber sources mainly changed the rumen community in terms of the phylum and genus abundances. Lambs fed SH with low starch level increased the final BW without affecting total volatile fatty acids (TVFA) concentrations.

Non-fiber Carbohydrates in Forages and Their Influence on Beef Production Systems

Forages can provide a complete diet for ruminant animals, increasing the sustainability of beef production systems worldwide while reducing competition with humans for agricultural land or grain crops. Much of the emphasis on the nutritional characteristics of forages has been on the fiber, sugars, starch, and protein they supply to the rumen, despite the fact that other less-explored constituents, i.e., neutral detergent soluble fiber (NDSF) and other non-structural or non-fiber carbohydrates (NFC) also play a key role in the nutrition of ruminants. This paper explores the less investigated potential of temperate legumes to accumulate levels of NFC comparable to corn silage or beet pulp in cool, dry environments under irrigation, and its implications for forage-based beef production systems. We conclude that genetic or managerial interventions (i.e., breeding programs, defoliation frequency) or ecological conditions (i.e., climate, elevation) that increase concentrations of NFC in legumes can enhance beef production, meat quality, and the efficiency of nitrogen utilization by ruminants while reducing environmental impacts.

Orange juice industry by-product silage can increase fat and protein in Holstein cow's milk

We aimed to evaluate the effect of replacing corn silage by orange peel silage on nutrient intake, ruminal parameters and milk production of multiparous lactating Holstein cows. Eight fistulated Holstein cows averaging 587.5 ± 39.6 kg and 111 ± 22 d in milking were randomly assigned to a double 4 × 4 Latin square design carried out two times to determine the effects of feeding with orange peel silage (OPS) in substitution of whole plant corn silage (WPCS). The treatments were a control diet with WPCS only or diets with OPS replacing WPCS in the total mixed diet (250, 500, or 750 g/kg DM). All cows were fed the same 750 : 250 g/kg roughage : concentrate ratio. The DM intake and milk production were reduced with the OPS inclusion, with decreases in consumption of neutral detergent fibre and increased consumption of non-fibrous carbohydrates. Diets with 250 and 500 g/kg OPS showed similar milk production and protein content in milk to the standard WCPS diet, whilst 750 g/kg orange peel silage as roughage increased fat and protein contents significantly. The orange peel silage as a substitute for corn silage for feeding dairy cows did not show adverse changes in the rumen environment and showed promising results in the increase of fat in milk of Holstein cows.

Milk Potential of Pantaneira Cows, a Local Breed, at Organic System

Simple Summary

Pantaneira cattle are descendants of the genetic group of crossed European animals and are a breed locally adapted to the Brazilian Pantanal. The use of this breed in organic systems can have benefits for the conservation of the breed and because it is a genetically rustic breed. The aim of this study was to evaluate the performance of Pantaneira primiparous cows under systems with reduced use of concentrate, simulating organic production conditions. There was a reduction in milk yield, but the energy-corrected milk yield and efficiency were not affected. The Pantaneira breed has the genetic potential for the maintenance of competitive production and quality in organic systems.

Abstract

Pantaneiro cattle (Bos taurus taurus) is a breed locally adapted to the Brazilian Pantanal. Local breeds are essential for the quality production of organic systems based on planned grazing practices, because of their results in resilient and productive ecosystems, enhancing biodiversity. This study aimed to evaluate the performance of Pantaneira primiparous cows, and systems with reduced use of concentrate, simulating organic production conditions. Five animals, with an average body weight of 396.2 ± 43.5 kg, were kept in individual continuous grazing regimes and supplemented with different concentrate levels (1.2%, 0.9%, 0.6%, 0.3%, and 0.0% of body weight). The animals were allocated at random in a 5 × 5 Latin square design repeated twice during the study time. The cows had a low dry matter and nutrient intake with a reduction in concentrate level, with improvement in neutral detergent fiber digestibility and a reduction in total nutrient digestibility. No changes were observed in plasma glucose levels or urea excretion, but the plasma urea nitrogen decreased with reductions in concentrate levels. There was a reduction in milk yield, but the energy-corrected milk was not affected by the reduction in concentrate levels; furthermore, the milk yield efficiency was not affected. The milk fat content improved with the reduction in concentrate levels. The Pantaneira breed has the genetic potential for the maintenance of competitive production and quality in organic systems.

Liquid hot water treatment of rice straw enhances anaerobic degradation and inhibits methane production during in vitro ruminal fermentation

Liquid hot water (LHW) treatment can be used to disrupt the fiber structure of rice straw. This in vitro ruminal batch culture study investigated the effect of LHW treatment on feed degradation, methane (CH₄) production, and microbial populations. Rice straw was treated by LHW, and in vitro ruminal fermentation was performed using an automatic system with 72 h of incubation. Scanning electron microscopy showed that LHW treatment disrupted the physical structure of rice straw. Liquid hot water treatment decreased neutral detergent fiber and hemicellulose contents of the rice straw and increased neutral detergent solubles, water-soluble carbohydrates, and arabinose contents. Liquid hot water treatment increased dry matter degradation and volatile fatty acid concentration and decreased the acetate:propionate ratio, CH₄ production, hydrogen accumulation, neutral detergent fiber degradation, and populations of protozoa, fungi, and cellulolytic bacteria. In summary, LHW treatment disrupted the cellulose-hemicellulose-lignin structure matrix of rice straw, leading to increased substrate degradability and decreased CH₄ production. Therefore, the LHW treatment is a potential strategy to improve the nutritive value of forage such as rice straw and decrease the CH₄ emissions in ruminants.

Urea plus nitrate pretreatment of rice and wheat straws enhances degradation and reduces methane production in in vitro ruminal culture

BACKGROUND

Urea pretreatment of straw damages fiber structure, while nitrate supplementation of ruminal diets inhibits enteric methane production. The study examined the combined effects of these treatments on ruminal substrate biodegradation and methane production using an in vitro incubation system. Rice and wheat straws were pretreated with urea (40 g kg^-1 straw dry matter, DM) and urea + ammonium nitrate (34 + 6 g kg^-1 dry matter (DM), respectively), and each straw (control, urea, urea+nitrate) was used in batch culture incubations in three replications (runs).

RESULTS

Urea pretreatment increased (P < 0.05) neutral-detergent solubles (NDS) content (+17%) and in vitro DM degradation of rice straw, in comparison with control. Urea+nitrate pretreatment of rice and wheat straws had higher (P < 0.05) NDS content, in vitro DM degradation and propionate molar proportion, and lower (P < 0.05) acetate:propionate ratio and lower methane production with a decline of methanogens, in comparison to control.

CONCLUSIONS

Urea+nitrate pretreatment combines positive effects of urea pretreatment and nitrate supplementation, and can be a potential strategy to improve ruminal biodegradation, facilitate propionate production and reduce methane production from lignified straws. © 2018 Society of Chemical Industry.

Peanut cake can replace soybean meal in supplements for lactating cows without affecting production

This study evaluated the total replacement of soybean meal with peanut cake in the concentrate supplement of lactating cows grazing. Eight crossbred 5/8 Holstein × 3/8 Zebu cows between the 45th and 60th day of lactation and 507 ± 35 kg BW were distributed in a 4 × 4 double Latin square design with four levels of peanut cake (0, 110, 220, and 330 g/kg of the dry matter-DM) as a replacement of soybean meal in the concentrate supplement. The intake of pasture, total (pasture + concentrate), crude protein (CP), neutral detergent fiber (NDF), total digestible nutrients, and digestibility of the DM, CP, ether extract (EE), and NDF was not affected by the replacement of soybean meal with peanut cake. However, the EE (P = 0.83) intake and non-fiber carbohydrate digestibility (P = 0.09) exhibited an increasing linear trend by the peanut cake inclusion. The NDF exhibited a decreasing linear trend (P = 0.07) as the level of peanut cake increased. Production, corrected production, and protein, fat, lactose, total solid, and non-fat solid composition concentrations in the cows' milk were not affected (P > 0.05) by the peanut cake inclusion. The protein/fat ratio exhibited an increasing linear trend (P = 0.082) by the peanut cake inclusion. Peanut cake can completely replace soybean meal in the concentrate mixture because it does not alter dry matter intake, production, and composition of milk, and in addition it can reduce the cost of feeding.

Effects of feeding different levels of dried orange pulp and recycled poultry bedding on the performance of fattening lambs

The effects of dietary feeding different levels of recycled poultry bedding (RPB) and dried orange pulp (DOP) on the performance of fattening Shal lambs (initial BW of 28 ± 2.2 kg) were assessed using a factorial experiment (2 × 3) with a completely randomized design. Six diets, containing different levels of RPB (0 or 160 g/kg of DM) and DOP (0, 110, or 220 g/kg of DM), were randomly assigned to 6 groups of 6 lambs each for a 74-d period (14 d for adaptation and 60 d for data collection). Diets were offered as total mixed ration to ensure 10% of orts. Feed intake, growth, diet digestibility, microbial nitrogen (N) synthesis (MNS), N retention, rumen fermentation parameters, and blood metabolites were determined. Data were analyzed using the PROC MIXED of SAS. Increasing RPB and DOP levels in the diet of the lambs improved ( < 0.05) DMI, ADG, and G:F. Diet digestibility was not affected by dietary feeding of RPB ( > 0.05), but increased as DOP level increased in the diet ( < 0.05). Feeding RPB and DOP had no effects ( > 0.05) on the ruminal pH. The ruminal total VFA concentration, molar proportion of acetic acid, and acetate-to-propionate ratio increased ( < 0.05) with the increasing dietary levels of RPB and DOP, while ammonia N concentration, propionic acid proportion, total protozoa count, and subfamily number decreased ( < 0.05). Including RPB and DOP in diet enhanced ( < 0.05) MNS and N retention. Feeding RPB-containing diets caused ( < 0.05) an increase of plasma glucose concentration and decreases ( < 0.05) of cholesterol and urea N. As the dietary level of DOP increased, the plasma concentrations of glucose, triglycerides, and urea N reduced ( < 0.05). The plasma antioxidant power was not affected ( > 0.05) by feeding RPB, but increased ( < 0.05) with increasing DOP level in diet. The animal performance reached its greatest value with simultaneous feeding of 160 g of RPB and 220 g of DOP per kg of diet DM. It has been concluded that the partial dietary substitution of RPB (instead of soybean meal, wheat bran, and sugar beet pulp) or/and DOP (instead of barley grain and corn grain) in fattening Shal lambs had positive effects on feed intake, diet digestibility, ruminal microbial N, growth, and N retention. Synchronized feeding of the great levels of RPB (as an N source) and DOP (as an energy source) increased utilization efficiency of these byproducts in the fattening lambs.

Review: Sugar beets as a substitute for grain for lactating dairy cattle

Dairy cows are customarily given grains and highly digestible byproduct ingredients as additions to forage to support milk production. In many parts of the world growing seasons are short, and the grain crops that can be grown may not provide adequate yields. Sugar beets, on the other hand are relatively hardy, and dry matter yields surpass the yields of most grain crops. There are however, perceptions that beets may not be suitable as a feed ingredient due to the fact that the storage form of carbohydrate is sugar rather than starch. With little analytical support, sugar has been rejected in many feeding programs with the view that sugar reduces rumen pH, fiber digestion and microbial yield. This review explores available facts revolving around these concerns. Information regarding the feeding of sugar beets is provided and the use of sugar beets as a partial replacement for grain is proposed.

Effects of substitution of barley with citrus pulp on diet digestibility and intake and production of lactating ewes offered mixed diets based on ammonia-treated barley straw

Twenty-eight lactating ewes (mean 48 (s.e. 0·37) kg live weight) were used from days 12 to 52 after lambing to evaluate the effects on digestibility and production performance of replacing barley grain with citrus pulp in diets based on ammonia-treated barley straw. Concentrates included 0·82 to 0·83 of different barley to citrus pulp proportions: 100: 0 (T1); 66: 33 (T2); 33: 66 (T3) and 0: 100 (T4), 0·115 of soya-bean meal, and urea to make diets isonitrogenous. Ewes were adapted to a common diet for 11 days after lambing, and then were given 850 g/day of each experimental concentrate together with 850 g/day of chopped barley straw for 14 days and milk production and lamb growth were recorded. During the following 14 days ewes received the same amount of concentrate but the straw was offered ad libitum and straw intake was recorded as well as milk production and lamb growth. After completing both periods, four ewes per treatment were used for total collections of faeces and urine. Apparent digestibility of organic matter and neutral-detergent fibre increased linearly (P < 0·05) with increasing levels of citrus pulp although no differences were found in the digestible organic matter content of dry matter of diets because of differences in ash content. Urinary excretion of allantoin and purine derivatives per unit of digestible organic matter intake tended to decrease with increasing inclusion of citrus pulp (proportionately by 0·15), suggesting a decrease in microbial protein synthesis, though this effect was not significant (P > 0·05). Faecal excretion of purine bases also decreased (P < 0·05) as citrus pulp inclusion increased. No treatment effect (P > 0·05) on ewe live weight, milk composition or serum glucose and 3–OH butyrate was observed when a 1: 1 straw to concentrate ratio was given, but milk production and lamb daily gain decreased linearly (P < 0·05) with increased proportions of citrus pulp in the concentrate. Similar responses were detected when straw was given ad libitum and differences among treatments in terms of straw intake were not identified. It is concluded that a lower microbial protein flow might explain in part the reduction in milk production observed when barley was replaced with citrus pulp.

Short communication: Evaluation of nitrogen excretion equations from cattle

Nitrogen excretion in dairy manure is a precursor for N2O and NH3 formation in livestock housing, manure storage facilities, and after manure is applied to land. Nitrous oxide is a major contributor to greenhouse gas emissions, and reducing N output from dairy production facilities can reduce the amount of anthropogenic N2O entering the atmosphere. The objective of the study was to conduct a comprehensive evaluation of extant prediction models for N excretion in feces and urine using extensive literature data. A total of 45 N excretion equations were evaluated for lactating cows, heifers, and nonlactating cows and steers. These equations were evaluated with 215 treatment means from 69 published studies collected over 20 yr from 1995 to 2015. Two evaluation methods were used: the root mean square prediction error and the concordance correlation coefficient. Equations constructed using a more rigorous development process fared better than older extant equations. Equations for heifers and nonlactating cows had greater error of prediction compared with equations used for lactating cows. This could be due to limited amount of data available for construction and evaluation of the equations. Urinary N equations had greater prediction errors than other forms of excretion, possibly due to high variability in urinary N excretion and challenges in urine collection. Fecal N equations had low error bias and reached an acceptable level of precision and accuracy.

Fatty Acid Profile of Milk and Cheese from Dairy Cows Supplemented a Diet with Palm Kernel Cake

Lipid supplements (oilseeds vegetables) are included in ruminant diet to increase its energy density and improve fatty acid composition of milk and consequently of fresh cheese. Milk and cheeses were evaluated from crossbred Holstein × Zebu, fed diets enriched with 0%, 25%, 50%, and 75% inclusion levels of palm kernel cake in concentrated supplement, which were supplied daily (3.0 kg). Milk and fresh cheese (p = 0.001) fatty acids C12:0 exhibited quadratic negative values. Milk fatty acids C13:0, C20:0, C18:2t10c12, and C20:2n-6 presented positive quadratic values. The milk C18:2n-6 decreased linearly and in fresh cheese exhibited an increasing linear effect (p = 0.016). However, the fatty acids grouped in milk fat were not affected. The medium-chain fatty acids varied negatively and quadratically (p = 0.045). There was no effect on milk and fresh cheese chemical composition (p > 0.05). The milk fat was increased (p = 0.0065) quadratically (minimum point of 24.7%). Thus, the addition of palm kernel cake to cow diets negatively altered the fatty acid profile, it raises the percentage of lauric (C12) and tridecanoic (C13) acids fat which is not beneficial to human health from a nutraceutical perspective, although it did not influence the atherogenicity index.

Saccharomyces cerevisiae live culture affects rapidly fermentable carbohydrates fermentation profile in precision-fed dairy heifers

Lascano, G. J., Heinrichs, A. J. and Tricarico, J. M. 2015. Saccharomyces cerevisiae live culture affects rapidly fermentable carbohydrates fermentation profile in precision-fed dairy heifers. Can. J. Anim. Sci. 95: 117–127. The experimental objective was to determine the dose effect of live yeast culture (YC) on rumen fermentation profiles and microbial total cell concentrations in precision-fed dairy heifers exposed to different rapidly fermented carbohydrates diets. A split-plot design with starch level as the whole plot and YC dose as sub-plot was administered in a four-period (21 d) 4×4 Latin square balanced for carryover effects. Eight Holstein heifers were allocated to two starch treatments (28% starch: HS; 17% starch: LS) and to a sequence of YC doses (0, 10, 30, and 50 g d−1). Total volatile fatty acid concentration was not different among YC doses or starch level, but molar proportions of propionate, isobutyrate, and isovalerate were higher for HS than for LS. Mean ruminal ammonia concentration was increased in HS-fed heifers. Heifers fed HS had an increased number of viable, non-viable, and total fluid-associated bacteria, particle-associated bacteria, and total bacteria. Increasing YC dose linearly beyond 10 g d−1 decreased viable and total fluid-associated bacteria. The effects of various YC doses on ruminal fermentation products, pH, and microbial total cell concentrations indicate diet dependency between source of readily available carbohydrates and YC addition in dairy heifers.

Performance of lactating crossbred cows on pasture supplemented with conventional urea or slow release urea

The effect of using conventional urea (CU) or slow release urea (SRU) was evaluated by replacing soybean meal (SBM) in concentrated supplements in levels of 2, 4 or 6% (dry matter basis) on productive performance of crossbred Holstein x Zebu lactating dairy cows (499±61kg body weight and 167 days of lactation) grazing on elephant grass (11.5% CP and 60% NDF) under rotational grazing during the rainy season. A supplement control (no urea) was used containing SBM as a protein source. A total of 21 cows were distributed an incomplete randomized block design with three periods of 21 days each (14 days of adaptation and seven days of collection). The animals entered the paddocks with a pasture height of 110-120cm and left when the grass reached the height of 40-50cm. The concentrated isonitrogenous supplements (24% crude protein, dry matter basis) were provided in the amount of 3.2kg/cow/day (fed basis). There was no effect (P>0.05) on source of crude protein (SBM vs source NPN), source NPN, level of NPN, interaction between source NPN and level of NPN on milk production (10.0kg/day), fat milk production corrected to 3.5% (10.7kg/day), levels of fat (4.01%), protein (3.66%), lactose (4.16%), total solids (12.86%) and non-fat solids (8.60%) in milk. The replacement of CU by SRU does not promote improvement in the productive performance of crossbred dairy cows grazing on elephant grass during the rainy season. Urea (CU or SRU) can be included in up to 6% of the DM concentrated supplements, replacing SBM, without affecting the productive performance of crossbred cows (Holstein x Zebu) in pasture during the rainy season.

Diets rich in starch increase the posthepatic availability of amino acids in dairy cows fed diets at low and normal protein levels

Five mid-lactation multicatheterized Jersey cows were used in a 4×4 Latin square design to investigate whether the increase in milk N yield associated with diets rich in starch versus fiber could originate from changes in the splanchnic AA metabolism and if these changes depended upon the dietary crude protein (CP) content. Four isoenergetic diets were formulated to provide 2 different carbohydrate compositions [diets rich in starch (350g of starch and 310g of neutral detergent fiber/kg of dry matter) versus rich in fiber (45g of starch and 460g of neutral detergent fiber/kg of dry matter)] crossed by 2 different CP contents (12.0 vs. 16.5% CP). At the end of each treatment period, 6 hourly blood samples were collected from the portal and hepatic veins as well as the mesenteric artery to determine net nutrient fluxes across the portal-drained viscera (PDV), liver, and total splanchnic tissues. Dry matter and calculated energy intake as well as total absorbed energy were similar across treatments. However, the net portal appearance (NPA) of acetate, total volatile fatty acids, and β-hydroxybutyrate were higher with diets rich in fiber versus starch, whereas that of oxygen, glucose, butyrate, and insulin were lower. Concomitant to these changes, the percentage of N intake recovered as total AA (TAA) in the portal vein was lower for diets rich in fiber versus starch (42.3 vs. 51.4%, respectively), without, however, any difference observed in the NPA of the main AA used as energy fuels by the PDV (Glu, Gln, and Asp). Despite a higher NPA of TAA with starch versus fiber diets, no differences in the net hepatic flux of TAA, essential and nonessential AA were observed, resulting in a higher (+22%) net splanchnic release of AA and, hence, a greater (+7%) milk N yield. The net hepatic flux and hepatic fractional removal of none of the individual AA was affected as the main carbohydrate changed from fiber to starch, except for Gly and Lys, which were higher for the latter. After correcting for differences in NPA of TAA, the net hepatic uptake of TAA tended to be lower with starch versus fiber diets. The higher transfer of N from feed to milk with diets rich in starch is not the consequence of a direct sparing AA effect of glucogenic diets but rather the result of lower energy requirements by the PDV along with a higher microbial N flow to the duodenum. A better AA use by peripheral tissues with starch versus fiber diets was also hypothesized but more studies are warranted to clarify this issue.

Silagem de grãos úmidos de milho de textura dura ou macia em dietas com polpa cítrica para vacas em lactação

Avaliou-se o desempenho de vacas leiteiras que consumiram polpa cítrica e dois teores dietéticos de silagem de grão úmido de milho. Os tratamentos foram: milho de textura dura ou milho de textura macia ensilado na linha negra, em fatorial com 9% ou 18% de milho na dieta. O teor de polpa cítrica na dieta foi de 16,2% ou 25,6%, com alto e baixo milho, respectivamente. Doze vacas receberam os tratamentos em quadrados latinos 4x4. A produção diária de leite foi 27,9kg no milho duro e 28,8 no macio (P=0,19). Alto milho diminuiu o teor de gordura do leite de 3,38 para 3,26% (P=0,04) e aumentou o teor de proteína de 2,99 para 3,03% (P=0,05) e a eficiência alimentar de 1,50 para 1,57kg de leite/kg de consumo (P=0,03). Aumento no teor de milho induziu maior queda no pH ruminal na dieta com milho macio do que na dieta com milho duro (P=0,05 para a interação textura versus teor de milho). O milho macio aumentou o consumo diário de matéria orgânica digestível de 11,7 para 12,3kg (P=0,05). Os parâmetros digestivos sugerem que a ensilagem não eliminou totalmente o efeito da textura do endosperma sobre a digestibilidade do milho.

Effects of different sources of carbohydrates on intake, digestibility, chewing, and performance of Holstein dairy cows

To investigate the effects of different sources of carbohydrates on intake, digestibility, chewing, and performance, nine lactating Holstein dairy cows (day in milk= 100±21 d; body weight=645.7 ± 26.5 kg) were allotted to a 3 × 3 Latin square design at three 23-d periods. The three treatments included 34.91% (B), 18.87% (BC), and 18.86% (BB) barley that in treatment B was partially replaced with only corn or corn plus beet pulp in treatments BC and BB, respectively. The concentration of starch and neutral detergent soluble carbohydrate varied (22.2, 20.2, and 14.5; 13.6, 15.9, and 20.1% of DM in treatments B, BC, and BB, respectively). Cows in treatment BB showed a higher DMI and improved digestibility of DM, NDF, and EE compared with treatments B or BC. Ruminal pH was higher in cows fed on BB (6.83) compared with those that received B or BC treatments (6.62 and 6.73, respectively). A lower proportion of propionate accompanied the higher pH in the BB group; however, a greater proportion of acetate and acetate: propionate ratio was observed compared with cows fed either on the B or BC diet. Moreover, cows fed on the BB diet showed the lowest ruminal passage rate and longest ruminal and total retention time. Eating time did not differ among treatments, rumination time was greater among cows fed on the BB diet compared with the others, whereas total chewing activity was greater than those fed on BC, but similar to those fed on B. The treatments showed no effect on milk yield. Partially replacing barley with corn or beet pulp resulted in an increase in milk fat and a lower protein concentration. Changing dietary NFC with that of a different degradability thus altered intake, chewing activity, ruminal environment, retention time or passage rate, and lactation performance. The results of this study showed that beet pulp with a higher NDF and a detergent-soluble carbohydrate or pectin established a more consistent ruminal mat than barley and corn, thus resulting in higher mean retention time and chewing activity, whereas no changes in 3.5% FCM and milk fat were observed.

Invited review: Role of physically effective fiber and estimation of dietary fiber adequacy in high-producing dairy cattle

Highly fermentable diets require the inclusion of adequate amounts of fiber to reduce the risk of subacute rumen acidosis (SARA). To assess the adequacy of dietary fiber in dairy cattle, the concept of physically effective neutral detergent fiber (peNDF) has received increasing attention because it amalgamates information on both chemical fiber content and particle size (PS) of the feedstuffs. The nutritional effects of dietary PS and peNDF are complex and involve feed intake behavior (absolute intake and sorting behavior), ruminal mat formation, rumination and salivation, and ruminal motility. Other effects include fermentation characteristics, digesta passage, and nutrient intake and absorption. Moreover, peNDF requirements depend on the fermentability of the starch source (i.e., starch type and endosperm structure). To date, the incomplete understanding of these complex interactions has prevented the establishment of peNDF as a routine method to determine dietary fiber adequacy so far. Therefore, this review is intended to analyze the quantitative effects of and interactions among forage PS, peNDF, and diet fermentability with regard to rumen metabolism and prevention of SARA, and aims to give an overview of the latest achievements in the estimation of dietary fiber adequacy in high-producing dairy cattle. Recently developed models that synthesize the effects of both peNDF and fermentable starch on rumen metabolism appear to provide an appropriate basis for estimation of dietary fiber adequacy in high-producing dairy cows. Data suggest that a period lasting more than 5 to 6h/d during which ruminal pH is <5.8 should be avoided to minimize health disturbances due to SARA. The knowledge generated from these modeling approaches recommends that average amounts of 31.2% peNDF inclusive particles >1.18mm (i.e., peNDF(>1.18)) or 18.5% peNDF inclusive particles >8mm (i.e., peNDF(>8)) in the diet (DM basis) are required. However, inclusion of a concentration of peNDF(>8) in the diet beyond 14.9% of diet DM may lower DM intake level. As such, more research is warranted to develop efficient feeding strategies that encourage inclusion of energy-dense diets without the need to increase their content in peNDF above the threshold that leads to lower DM intake. The latter would require strategies that modulate the fermentability characteristics of the diet and promote absorption and metabolic capacity of ruminal epithelia of dairy cows.

Produção e composição do leite de vacas em pastagem de capim-elefante (Pennisetum purpureum) suplementado com diferentes fontes de carboidratos

Avaliaram-se os efeitos da silagem de grãos úmidos de milho e da substituição parcial ou total de milho seco por polpa de citrus sobre a produção e a composição do leite de vacas mantidas em pastejo de capim-elefante, manejado intensivamente. Foram utilizadas 12 vacas da raça Holandesa, "de alta cruza" distribuídas em quatro tratamentos, em delineamento do tipo quadrado latino. Todas as vacas receberam concentrados que diferiram nas fontes de carboidratos: milho-grão seco moído, polpa de citrus mais milho grão seco moído, polpa de citrus e silagem de grãos úmidos de milho. Não foi detectada diferença (P>0,05) na produção de leite total, de leite corrigido para gordura (LCG 3,5) e para sólidos (LCS) entre tratamentos. Vacas que receberam milho-grão seco e silagem de milho de alta umidade apresentaram maior porcentagem de proteína e sólidos totais no leite (P<0,05), e as que receberam polpa de citrus, maior porcentagem de gordura (P<0,01). As que consumiram silagem de grãos úmidos apresentaram menor valor de nitrogênio ureico no leite (P<0,05). A ausência de resposta positiva ao processamento do milho pode ser razão do potencial de produção do sistema em pasto e do estresse calórico sofrido pelos animais. Em critérios de pagamento do leite em que a composição não tem valor econômico definido, qualquer uma das fontes de carboidratos testados no presente estudo pode ser utilizada.

Carbohydrate source and protein degradability alter lactation, ruminal, and blood measures

Thirty-eight lactating dairy cows including 6 ruminally cannulated cows were used in a feeding study to assess effects of feed sources that differed in dietary nonfiber carbohydrate (NFC) composition and ruminal degradability of dietary protein (RDP) on production, ruminal, and plasma measures. The design was a partially balanced, incomplete Latin square with three 21-d periods and a 3 x 2 factorial arrangement of treatments. Samples and data were collected in the last 7 d of each period. Feed sources that differed in NFC profile were dry ground corn (GC; starch), dried citrus pulp (DCP; sugar and pectins), and sucrose+molasses (SM; sugar). Dietary RDP was altered by providing CP with soybean meal (+RDP) or substituting a heat-treated expeller soybean product for a portion of the soybean meal (-RDP). Diets were formulated to be isonitrogenous and similar in NFC concentration. Cows consuming GC had the greatest milk urea nitrogen and milk protein percentage and yield, tended to have the greatest dry matter intake, but had a lesser milk fat percentage compared with cows consuming DCP and SM. Sucrose+molasses diets supported greater dry matter intake, milk protein yield, and 3.5% fat- and protein-corrected milk yield than did DCP diets. On -RDP diets, milk protein percentage was less and milk urea nitrogen and protein yield tended to be less than for +RDP diets. Dry ground corn diverged from DCP and SM in the effect of NFC x RDP, with cows consuming GC having lesser milk yield, 3.5% fat- and protein-corrected milk yield, and efficiency with -RDP as compared with +RDP, whereas these production measures were greater with -RDP than +RDP for cows consuming DCP and SM. In contrast, in situ NDF digestibility at 30h for GC and SM was greater for -RDP as compared with +RDP, but the reverse was true for DCP. The lowest ruminal pH detected by 6h postfeeding was also influenced by the interaction of NFC x RDP, with cows consuming SM having a lower pH with +RDP than with -RDP and cows consuming DCP having a similar pH on either RDP treatment. Total rumen volatile fatty acid concentrations did not differ among diets, but acetate molar percent was greater for DCP than for SM, and GC had the lowest molar percent for butyrate and valerate and greatest branched-chain volatile fatty acid concentration. Valerate molar percent and NH(3) concentration tended to be greater with +RDP than with -RDP. Plasma glucose and insulin were both greater in cows receiving SM than in those receiving DCP. Protein degradability, NFC source, and their interactions affected lactation, ruminal, and blood measures, suggesting that these dietary factors warrant further consideration in diet formulation.

Replacement of starch from corn with nonforage fiber from distillers grains and soyhulls in diets of lactating dairy cows

Forty Holstein cows were used in a completely randomized design with a 2-wk covariate period followed by a 6-wk experimental period to evaluate incremental substitution of nonforage fiber provided by dried distillers grains with solubles (DDGS) and soyhulls (SH) for starch provided by corn in the diet. Diets provided decreasing concentrations of starch: 29% starch with 0% DDGS; 26% starch with 7% DDGS; 23% starch with 14% DDGS; and 20% starch with 21% DDGS. Diets contained 27% corn silage, 22% alfalfa hay, and 51% concentrate mix and were formulated to be 17% crude protein, 4.7% fat, and 23% neutral detergent fiber from forage. Total neutral detergent fiber increased as DDGS and SH were included in the diet. Soyhulls were included in a linear fashion along with DDGS to replace soybean meal and expeller soybean meal, thereby maintaining a similar crude protein content across diets. Dry matter intake decreased linearly; consequently, feed efficiency tended to increase linearly as starch was replaced by nonforage fiber. There was no effect of diet on milk production or milk fat and protein percentage or yield. Milk fatty acid profiles were similar across diets. Other response variables, including 4% fat-corrected milk, total solids, and milk urea nitrogen, were unaffected by dietary treatments. Ruminal volatile fatty acid concentration did not differ between diets. Concentrations of blood glucose and beta-hydroxybutyrate were similar across diets. Results from this research suggest that nonforage fiber from DDGS can partially substitute for starch from corn in dairy cow diets without affecting milk production and milk composition. Economic analysis of the diets showed that feeding DDGS and SH in substitution of corn was cost-effective. Results from this experiment indicate that DDGS and SH can replace corn as an energy source to decrease feed costs.

Effects of feeding fresh citrus pulp to Merino wethers on wool growth and animal performance

Two studies were conducted to determine the effects of replacing lupins with fresh citrus pulp in Merino wethers diets: (i) an in vitro study, which measured ruminal fermentation; and (ii) an in vivo study in which 18 mature Merino wethers were fed dietary treatments (n = 3) over 56 days to evaluate effects on performance [i.e. DM intake, average daily gain and wool growth]. In both the in vitro and in vivo studies, the control treatment consisted (in diet DM) of lucerne chaff (69.9%), lupins (30.1%) and phosphate (0.3%), whereas the citrus pulp treatments (n = 2; replacing lupins on 20 and 30% DM basis, respectively) consisted of lucerne chaff (61.7 and 63.3%), lupins (18.5 and 6.3%), phosphate (0.34 and 0.33%) and fresh citrus pulp (19.5 and 30.1%). Data were analysed using the MIXED model of SAS and orthogonal polynomial contrasts were used to determine linear (L) and quadratic responses to the level of citrus pulp. In the in vitro study, gas production, net total volatile fatty acid production as well as in vitro DM digestibility were similar (P > 0.05) among the dietary treatments. Ammonia production in citrus pulp treatments were twofold lower compared with the control (L, P < 0.01). The addition of citrus pulp to the diet increased the molar proportions of acetic acid and decreased that of butyric, branched-chain volatile fatty acids, and valeric acids (all L, P < 0.01) compared with the control diet. In the in vivo study, DM intake, average daily gain and feed conversion were similar among treatments (P > 0.52). Wool production parameters including clean fleece weight, yield and staple length were not different between diets (P > 0.30). Hence, fresh citrus pulp can be included up to 30% on a DM basis replacing lupins without detrimental effects on wool production and animal performance.