Estimation of Rumen Microbial Protein Supply Using Urinary Purine Derivatives Excretion in Crossbred Calves Fed at Different Levels of Feed Intake

Effects of supplemental fat sources and forage feeding levels on growth performance, nutrient digestibility, ruminal fermentation, and nitrogen utilization in dairy calves

Knowledge regarding the potential interactions between supplemental fat source and fiber level in starter diet of dairy calves is lacking. The aim of the present study was to investigate the effects of supplemental saturated fat [palm fat (PLF) containing 86% palmitic acid (C16:0)] vs. unsaturated fat [soybean oil (SBO) containing 51% linoleic acid (C18:2)] and forage level on feed intake, growth performance, ruminal fermentation, nutrient digestibility, and metabolic traits in dairy calves. Forty newborn Holstein female calves (BW = 39.7 ± 1.8 kg) were assigned to 1 of 4 treatment groups (each consisting of 10 animals) in a 2 × 2 factorial arrangement of fat source [soybean oil vs. palm fat; 3% of starter based on DM basis] and alfalfa hay level (0 vs. 15%, on DM basis): SBO or PLF with (AH) or without (NAH) alfalfa hay. Calves had ad libitum access to water and starters throughout the study and a constant amount of milk was offered among experimental calves during the pre-weaning period. All calves were weaned on day 63 of age and remained in the study until day 73 of age. The results showed that the lowest and the highest starter intake and average daily gain during pre-weaning period was observed when calves received SBO-AH and PLF-AH, respectively. Accordingly, the lowest wither and hip heights at weaning time (day 63) and final wither height (day 73) were observed in SBO-AH group across treatments. Calves received PLF-AH had the highest weaning and final BW compared to other groups. Feed efficiency tended to be higher in PLF groups compared with SBO calves. Calves fed SBO-AH had the lowest digestibility of organic matter and neutral detergent fiber and also total short chain fatty acid concentrations in rumen compared with other groups. The SBO calves had lower urinary allantoin, urinary purine derivatives, and microbial protein synthesis than PLF calves; however, urinary nitrogen increased with SBO supplementation. In summary, the supplementation of SBO rich in C18:2 and AH during the pre-weaning period resulted in negative responses on growth performance, digestibility, and ruminal fermentation profile. Therefore, the inclusion SBO rich in C18:2 along with forage in the starter is not recommendable for young dairy calves.

Effect of increasing dietary proportion of plantain on milk production and nitrogen use of grazing dairy cows in late lactation

Abstract Context Plantain has shown promise as a forage that can mitigate nitrogen (N) losses from farm systems, although adoption and regulation requires knowledge of the minimum amount of forage area or diet quantity to observe an effect. Aims A grazing study was conducted to evaluate the effect of offering increasing proportions of spatially adjacent plantain (PL) and perennial ryegrass–white clover (PRGWC) on milk production and N utilisation of dairy cows. Methods Forty-eight late lactating cows blocked into replicated (n = 3) groups of four cows were randomly allocated to one of the following four forage treatments based on percentage area of plantain: 0%, 15%, 30%, or 60%. Cows were allocated 25 kg DM/cow.day of forage above ground level daily on the basis of metabolisable energy requirements. Dry matter intake was estimated from the difference between pre- and post-grazing pasture mass, using a calibrated electronic rising-plate meter. Milk production was measured as yield and milk solids, while N use was estimated from total milk N excretion and spot subsamples of blood, urine and faeces. Key results Offering cows spatially adjacent strips of PL increased apparent dry matter intake compared with PRGWC pasture alone (16.4 vs 15.1 kg DM/cow.day, P = 0.027) and apparent metabolisable energy intake (203 vs 188 MJ/kg.cow.day, P < 0.001). Milk yield (16.1 kg/cow.day), milk solids production (1.6 kg/cow.day) and fat concentration (5.69%) were unaffected by the proportion of plantain in the diet. PL offered at 60% of the area increased milk protein concentration compared with PRGWC (4.65 vs 4.36%, P < 0.01). There was no treatment effect on total apparent N intake (563 g N/cow.day), N excretion in milk (113 g N/cow.day) and N-utilisation efficiency (20 g milk N/100 g N consumed). However, total milk urea, blood urea and urine urea N concentrations declined with increasing plantain in the diet, reflecting an influence on urea metabolism. Conclusions Offering plantain to grazing dairy cows did not improve milk yield or N-use efficiency, but influenced urea metabolism. Implications Sowing plantain in spatially separate strips within perennial ryegrass–white clover pastures is a useful option to achieve target levels of plantain in the diet and, in conjunction with other mitigation strategies, can be used to improve the sustainability of pastoral dairy farming.

Tannin supplementation modulates the composition and function of ruminal microbiome in lambs infected with gastrointestinal nematodes

This study was carried out to evaluate the effects of tannin supplementation on ruminal microbiota of sixteen lambs infected and non-infected with Haemonchus contortus and Trichostrongylus colubriformis. Animals were fed with hay, concentrate and supplemented with Acacia mearnsii (A. mearnsii). The animals were divided into four treatments: two control groups without infection, either receiving A. mearnsii (C+) or not (C-), and two infected groups, one with A. mearnsii (I+) and another without A. mearnsii (I-). Ruminal short-chain fatty acids (SCFA) and metagenome sequencing of ruminal microbiota were used to evaluate the effect of tannin and infection on ruminal microbiome. For SCFA, differences were observed only with A. mearnsii. Total SCFA and acetate molar percentage were decreased in C+ and I+ (P<0.05). Butyrate, valerate and isovalerate were higher in lambs that received A. mearnsii in the diet (P<0.05). The infection changed the microbiome structure and decreased the abundance of butyrate-producing microorganisms. In addition, A. mearnsii supplementation also affected the structure the microbial community, increasing the diversity and abundance of the butyrate-producing and probiotics bacteria, amino acid metabolic pathways, purine, pyrimidine and sphingolipid metabolism. Together, our findings indicate that A. mearnsii supplementation modulates important groups related to nitrogen, amino acid, purine and pyrimidine metabolism, in rumen microbiome, affected by gastrointestinal nematodes infection in lambs.

Dietary Supplementation with Sodium Sulfate Improves Rumen Fermentation, Fiber Digestibility, and the Plasma Metabolome through Modulation of Rumen Bacterial Communities in Steers

Six steers were used to study the effects of dietary supplementation with sodium sulfate (Na₂SO₄) on rumen fermentation, nutrient digestion, rumen microbiota, and plasma metabolites. The animals were fed a basal ration with Na₂SO₄ added at 0 g/day (sulfur [S] content of 0.115% dry matter [DM]), 20 g/day (S at 0.185% DM), or 40 g/day (S at 0.255% DM) in a replicate 3-by-3 Latin square design. The results indicated that supplementing with Na₂SO₄ increased the ruminal concentration of total volatile fatty acids, the molar proportions of acetate and butyrate, the ruminal concentrations of microbial protein, SO₄ ^2--S, and S^2--S, and the digestibility of fiber, while it decreased the molar proportion of propionate and the ruminal concentration of ammonia nitrogen. Supplementing with Na₂SO₄ increased the diversity and the richness of rumen microbiota and the relative abundances of the phylum Firmicutes and genera Ruminococcus 2, Rikenellaceae RC9 gut group, and Desulfovibrio, whereas it decreased the relative abundances of the phylum Bacteroidetes and genera Prevotella 1, Prevotellaceae UCG-001, and Treponema 2 Supplementing with Na₂SO₄ also increased the plasma concentrations of amino acids (l-arginine, l-methionine, l-cysteine, and l-lysine), purine derivatives (xanthine and hypoxanthine), vitamins (thiamine and biotin), and lipids (acetylcarnitine and l-carnitine). It was concluded that supplementing the steer ration with Na₂SO₄ was beneficial for improving the rumen fermentation, fiber digestibility, and nutrient metabolism through modulating the rumen microbial community.IMPORTANCE Essential elements like nitrogen and sulfur greatly affect rumen fermentation and metabolism in ruminants. However, little knowledge is available on the effects of sulfur on the rumen microbiota and plasma metabolome. The results of the present trial demonstrated that supplementing the steer ration with sodium sulfate markedly improved rumen fermentation, fiber digestibility, and metabolism of amino acids, purine derivatives, and vitamins through effects on the ruminal microbiome. The facts obtained from the present trial clarified the possible mechanisms of the positive effects of sulfur on rumen fermentation and nutrient utilization.

Milk production responses and rumen fermentation of dairy cows supplemented with summer brassicas

Forage brassicas, such as summer turnip (ST; Brassica rapa) and forage rape (FR; Brassica napus), are used as supplementary crops during summer. However, studies with lactating dairy cows fed these forages are limited and report inconsistent productive responses. The aim of this study was to determine dry matter intake, rumen fermentation and milk production responses of dairy cows in mid-lactation supplemented with and without summer ('ST' or 'FR') brassicas. Twelve multiparous lactating dairy cows were randomly allocated to three dietary treatments in a replicated 3 × 3 Latin square design balanced for residual effects over three 21-day periods. The control diet consisted of 16.2 kg DM of grass silage, 2.25 kg DM of commercial concentrate and 2.25 kg DM solvent-extracted soybean meal. For the other two dietary treatments, 25% of the amounts of silage and concentrates were replaced with FR or ST. The inclusion of forage brassicas had no effects on milk production (24.2 kg cow/day average) and composition (average milk fat and protein 43.2 and 33.6 g/l, respectively). Dry matter intake was 0.98 kg and 1.12 kg lower for cows supplemented with FR and ST, respectively, resulting in a greater feed conversion efficiency (1.35 kg milk/kg DM for ST and FR v. 1.27 kg milk/kg DM for the control diet). Intraruminal pH was lower for cows supplemented with ST compared to the control diet; however, it did not decrease below pH 5.8 at any time of the day. After feeding, the concentrations of total short-chain fatty acids (SCFAs) in rumen contents increased with ST supplementation compared to the control diet. Inclusion of FR in the diet increased the molar proportion of acetate (68.5 mmol/100 mmol) in total SCFA at the expense of propionate, measured 6 h after feeding of the forage. The molar proportion of butyric acid was greater with ST and FR supplementation (13.1 and 12 mmol/100 mmol, respectively) than in control cows. The estimated microbial nitrogen (N) flow was 89.1 g/day greater when supplementing FR compared to the control diet. Based on the haematological measures, the inclusion of summer brassica forages did not affect the health status of the animals. These results indicate that mid-lactation dairy cows fed brassicas are able to maintain production despite the reduced intake, probably due to improved rumen fermentation and therefore nutrient utilization.

Effects of replacement of para-grass with oil palm compounds on body weight, food intake, nutrient digestibility, rumen functions and blood parameters in goats

Objective

The aim of the present study was to investigate the beneficial effects of dietary supplementation with oil palm frond (leaf) (OPF) with and without oil palm meal (OPM) on nutrient intake and digestibility, ruminal fermentation and growth performance in goats.

Methods

Six female crossbred goats were fed for 28 days of 3 diet treatments; 100% para-grass (T1); 50% para-grass + 50% OPF (T2), and 30% para-grass + 50% OPF + 20% OPM (T3). Body weight, rectal temperature, respiratory rate, and urine volume, food intake, dry matter intake and water intake were measured daily. Nutrient digestibility was determined from five consecutive days of last week in each diet. Ruminal fluid, urine and blood were collected at the end for determination of rumen protozoa and volatile fatty acid contents, urinary allantoin excretion, blood cell count and chemistry profiles.

Results

Goats fed T2 and T3 showed higher dry matter and nutrients intakes while protein digestibility was suppressed compared with those for T1. Crude fat digestibility declined in T2 but maintained after adding the OPM (T3). High fat intake by giving OPF and OPM corresponded to a higher ruminal acetate/propionate ratio (C2/C3) and serum cholesterol level. An increased urinary allantoin/creatinine ratio was found in T2 and T3 compared with T1, implying an increased number of ruminal microbes.

Conclusion

Increased dry matter intake in T2 and T3 suggested that oil palm by-products are partly useful as a replacement for para-grass in goats. Replacement with the by-products increased plasma cholesterol level, which suggested that these products are a useful energy source. Changes in rumen parameters suggested an increased microbial number and activity suitable for acetate production. However, the limited digestibility of protein implies that addition of high protein feeds may be recommended to increase body weight gain of goats.

Effect of corn supplementation on purine derivatives and rumen fermentation in sheep fed PKC and urea-treated rice straw

This study investigated the effect of different levels of corn supplementation as energy source into palm kernel cake–urea-treated rice straw basal diet on urinary excretion of purine derivatives, nitrogen utilization, rumen fermentation, and rumen microorganism populations. Twenty-seven Dorper lambs were randomly assigned to three treatment groups and kept in individual pens for a 120-day period. The animals were subjected to the dietary treatments as follows: T1: 75.3% PKC + 0% corn, T2: 70.3% PKC + 5% corn, and T3: 65.3% PKC + 10% corn. Hypoxanthine and uric acid excretion level were recorded similarly in lambs supplemented with corn. The microbial N yield and butyrate level was higher in corn-supplemented group, but fecal N excretion, T3 has the lowest level than other groups. Lambs fed T3 had a greater rumen protozoa population while the number of R. flavefaciens was recorded highest in T2. No significant differences were observed for total bacteria, F. succinogenes, R. albus, and methanogen population among all treatment. Based on these results, T3 could be fed to lambs without deleterious effect on the VFA and N balance.