Two experiments were conducted to investigate the effects of a Saccharomyces cerevisiae fermentation product (XP, Diamond V, Cedar Rapids, IA) on in vitro ruminal fermentation of single forage and mixed diets. In Exp. 1, an in vitro test was used to determine the effects of various concentrations (0, 1, 2, and 3 g/L) of XP on ruminal fermentation of the major forage sources of China (rice straw, RS; corn stover, CS; corn silage without grain, CSNG; and corn silage with grain, CSG). Total VFA reached a peak at 1 g/L XP for RS, CSNG, and CSG and increased linearly (P < 0.01) for CS. The molar proportion of acetate decreased and propionate increased linearly (P < 0.01) with an increasing amount of XP for RS, CS, and CSNG. Microbial protein (MCP) increased linearly (P < 0.01) with an increasing level of XP for RS, and it reached peak values at 1 and 2 g/L XP for CSG and CSNG, respectively. Fungi population was increased (P < 0.05) with 1 g/L XP for all forages except CSNG. The population of Ruminococcus flavefaciens increased (P < 0.05) at 1 or 2 g/L XP for RS, CSNG, and CSG. In Exp. 2, the effects of 3 concentrations of XP (0, 1, and 2 g/L) were tested on in vitro ruminal fermentation of 3 mixed diets with various ingredient combinations: 1) CSC (corn:soybean meal:corn stover = 33:22:45), 2) CSCC (corn:soybean meal:corn stover:corn silage = 33:22:22.5:22.5), and 3) CSCCA (corn:soybean meal:corn stover:corn silage:alfalfa = 33:22:19:21:5). Total VFA concentrations were influenced by diets (P < 0.01) and were enhanced linearly by increasing concentrations of XP (P < 0.01). The molar proportion of acetate was reduced (P < 0.01), but the propionate proportion was enhanced with increasing concentrations of XP (P < 0.01). Ammonia N was decreased and MCP was increased by the addition of XP (linear, P < 0.01; quadratic, P < 0.05). The fungi population was greater with XP addition (quadratic, P < 0.01). The percentage of R. albus was affected by diets (P < 0.01), the level of XP (linear and quadratic, P < 0.01), and their interaction (P < 0.01). From these 2 in vitro studies, it is inferred that the addition of XP could improve the rumen fermentation of forages and mixed diets by stimulating the number of fiber-digesting rumen microbes, especially fungi populations.

The objectives of this study were to evaluate the effects of different supplemental levels of Saccharomyces cerevisiae fermentation product (SCFP; Original XP; Diamond V) on lactation performance in Holstein dairy cows under heat stress. Eighty-one multiparous Holstein dairy cows were divided into 27 blocks of 3 cows each based on milk yield (23.6±0.20 kg/d), parity (2.88±0.91) and day in milk (204±46 d). The cows were randomly assigned within blocks to one of three treatments: 0 (control), 120, or 240 g/d of SCFP mixed with 240, 120, or 0 g of corn meal, respectively. The experiment was carried out during the summer season of 2014, starting from 14 July 2014 and lasting for 9 weeks with the first week as adaption period. During the experimental period, average daily temperature-humidity index (measured at 08:00, 14:00, and 20:00) was above 68, indicating that cows were exposed to heat stress throughout the study. Rectal temperatures tended to decrease linearly (p = 0.07) for cows supplemented with SCFP compared to the control cows at 14:30, but were not different at 06:30 (p>0.10). Dry matter intake was not affected by SCFP supplementation (p>0.10). Milk yield increased linearly (p<0.05) with increasing levels of SCFP. Feed efficiency (milk yield/dry matter intake) was highest (p<0.05) for cows fed 240 g/d SCFP. Cows supplemented with SCFP gained (p<0.01) body weight, while cows in the control lost body weight. Net energy balance also increased linearly (p<0.01) with increasing levels of SCFP. Concentrations of milk urea nitrogen (p<0.01) decreased linearly with increasing levels of SCFP, while no difference (p>0.10) was observed among the treatments in conversion of dietary crude protein to milk protein yield. In summary, supplementation of SCFP alleviated the negative effect of heat stress in lactating Holstein dairy cows and allowed cows to maintain higher milk production, feed efficiency and net energy balance. Effects of SCFP were dose-dependent and greater effects were observed from higher doses.

This study aims to determine the effects of alfalfa supplementation on the pre- and postweaning performance, rumen development, and feed transition in starter diet-fed lambs. Six of 66 male Hu lambs were slaughtered at the age of 10 d to serve as a control. The other 60 lambs were randomly allocated to 2 dietary treatments: milk replacer and starter pellets without (STA) or with free-choice chopped alfalfa (S-ALF). The animals were offered 300 g/d of the concentrate mixture and had free access to alfalfa after weaning at the end of wk 4 (age 38 d). The alfalfa inclusion in the S-ALF group tended to increase the starter intake before weaning, significantly increased the concentrate intake soon after weaning ( < 0.05), and increased the BW ( < 0.01) and ADG ( < 0.10) in pre- and postweaning lambs. The S-ALF group had heavier carcasses ( < 0.05), rumens ( < 0.05), reticula ( < 0.05), omasums ( < 0.10), abomasums ( < 0.05), and visceral organs ( < 0.10) than the STA lambs after weaning. Alfalfa supplementation increased ( < 0.05) the rumen papillae length and the ratio of the duodenal villus height to the crypt depth; it also decreased ( < 0.05) the concentration and molar proportion of propionate in wk 1 and 5. The STA lambs had higher ( < 0.01) blood concentrations of globulin and blood urea nitrogen and lower β-hydroxybutyrate after weaning. The STA group also had a higher incidence of feed plaque. From the above results, we infer that the free-choice addition of chopped alfalfa to starter diets is beneficial to rumen development, relieves weaning stress, and improves the performance of lambs.

This study was conducted to investigate effects of disodium fumarate (DF) on fermentation characteristics and microbial populations in the rumen of Hu sheep fed on high-forage diets. Two complementary feeding trials were conducted. In Trial 1, six Hu sheep fitted with ruminal cannulae were randomly allocated to a 2 3 2 cross-over design involving dietary treatments of either 0 or 20 g DF daily. Total DNA was extracted from the fluid-and solid-associated rumen microbes, respectively. Numbers of 16S rDNA gene copies associated with rumen methanogens and bacteria, and 18S rDNA gene copies associated with rumen protozoa and fungi were measured using real-time PCR, and expressed as proportion of total rumen bacteria 16S rDNA. Ruminal pH decreased in the DF group compared with the control (P , 0.05). Total volatile fatty acids increased (P , 0.001), but butyrate decreased (P , 0.01). Addition of DF inhibited the growth of methanogens, protozoa, fungi and Ruminococcus flavefaciens in fluid samples. Both Ruminococcus albus and Butyrivibrio fibrisolvens populations increased (P , 0.001) in particle-associated samples. Trial 2 was conducted to investigate the adaptive response of rumen microbes to DF. Three cannulated sheep were fed on basal diet for 2 weeks and continuously for 4 weeks with supplementation of DF at a level of 20 g/day. Ruminal samples were collected every week to analyze fermentation parameters and microbial populations. No effects of DF were observed on pH, acetate and butyrate (P . 0.05). Populations of methanogens and R. flavefaciens decreased in the fluid samples (P , 0.001), whereas addition of DF stimulated the population of solid-associated Fibrobacter succinogenes. Population of R. albus increased in the 2nd to 4th week in fluid-associated samples and was threefold higher in the 4th week than control week in solid samples. Analysis of denaturing gradient gel electrophoresis fingerprints revealed that there were significant changes in rumen microbiota after adding DF. Ten of 15 clone sequences from cut-out bands appearing in both the 2nd and the 4th week were 94% to 100% similar to Prevotella-like bacteria, and four sequences showed 95% to 98% similarity to Selenomonas dianae. Another 15 sequences were obtained from bands, which appeared in the 4th week only. Thirteen of these 15 sequences showed 95% to 99% similarity to Clostridium sp., and the other two showed 95% and 100% similarity to Ruminococcus sp. In summary, the microorganisms positively responding to DF addition were the cellulolytic bacteria, R. albus, F. succinogenes and B. fibrisolvens as well as proteolytic bacteria, B. fibrisolvens, P. ruminicola and Clostridium sp.

A 59-day experiment compared the effects of increasing tea seed (Camellia sinensis L.) saponin (TSS) supplementation on dry matter intake (DMI), liveweight (LW), rumen fermentation, methanogenesis, blood biochemistry and animal tolerance. Six, 10, 15, 20, 25 and 30 g of powder TSS were dissolved during 5, 7, 4, 3, 3 and 2 days, respectively, and infused into the rumen of four rumen-cannulated Brahman steers (234 ± 13.6 kg LW; least-squares means ± s.e.m.) or mixed in the basal diet [BD: 0.15 Rhodes grass (Chloris gayana) hay plus a high-grain feed (0.85)] of two non-cannulated (253 ± 19.3 kg) steers. Overall, DMI was not affected, by the sequential infusion of TSS (5.3 ± 0.15 kg) or addition to the BD (5.4 ± 0.18 kg), but relative to all diets, 6 g of TSS supplementation reduced DMI (P < 0.05), while the administration above 30 g of the supplement was associated with significantly (P < 0.001) reduced DMI, scours and bloat disorders. Clinical symptoms disappeared 8 days after withdrawal of the supplement. LW increased with time (P < 0.05) and the final LW was similar for cannulated (258 ± 13.6 kg) and non-cannulated (276 ± 19.3 kg) steers. Saponin supplementation reduced total volatile fatty acid (VFA) concentration (P < 0.05), modified pattern of individual molar VFA concentrations and moderately increased ruminal pH (P < 0.05). Cannulated and non-cannulated steers fed the BD had similar daily (g) methane or yield (CH4 g/kg DMI) emissions while in respiratory chambers. However, compared with cannulated (8.0 ± 1.20 ng/mL) animals, the addition of 30 g of TSS in the BD increased (P < 0.01) blood CH4 concentration in non-cannulated (15.6 ± 1.74 ng/mL) animals. Diets supplemented with 30 g of TSS were associated with higher chloride (P < 0.01) and alkaline phosphatase (P < 0.05) blood concentrations, and lower serum concentrations of potassium and urea nitrogen (P < 0.01), iron and total lipase (P < 0.05), than was the BD. It was concluded that higher levels of TSS supplement may evoke physiological changes in the animal. However, the potential CH4 mitigation effect of this form of saponin in tropical cattle needs further investigation, alongside the derived response of the rumen microbial ecology to the tested range of supplementation.

This study was conducted to investigate the effects of rumen-protected γ-aminobutyric acid (GABA) on feed intake, growth performance and expression of related genes in growing lambs. A total of 24 lambs weaned at age of 50 days were divided into four block of six based on their BW, six lambs within a block were allocated to three pairs, which were then assigned randomly to three treatments with addition of rumen-protected GABA at levels of 0, 70 or 140 mg/day for 6 weeks. Dry matter intake was recorded weekly in three consecutive days, and BW was recorded every two weeks. At the end of the trial, four lambs from each group were slaughtered, and duodenum and ileum mucosa were obtained for measurement of mRNA abundance of GABA receptor and cholecystokinin receptor. Dry matter intake was higher ( P < 0.01) in the lambs fed 140 mg/day GABA than that in the control or 70 mg GABA-fed lambs. Average daily gain and nutrients digestibility were not different ( P > 0.05) among treatments. Lambs fed 140 mg/day GABA had higher mRNA abundance of GABA-B receptor ( P < 0.01) and lower mRNA abundance of cholecystokinin-2 receptor ( P < 0.01) in duodenum mucosa. Serum CCK content was lower ( P < 0.01) in lambs fed 140 mg/day GABA than that in control. It is indicated that GABA may enhance feed intake by regulating GABA-and cholecystokininrelated genes.