Feeding yeast culture fermentation products has been associated with improved feed intake and milk yield in transition dairy cows. These improvements in performance have been further described in terms of rumen characteristics, metabolic profile, and immune response. The objective of this study was to evaluate the effects of a commercial yeast culture product (YC; Culture Classic HD, Phibro Animal Health) on performance, blood biomarkers, rumen fermentation, and rumen bacterial population in dairy cows from -30 to 50 d in milk (DIM). Forty Holstein dairy cows were enrolled in a randomized complete block design from -30 to 50 DIM and blocked according to expected calving day, parity, previous milk yield, and genetic merit. At -30 DIM, cows were assigned to either a basal diet plus 114 g/d of ground corn (control; n = 20) or a basal diet plus 100 g/d of ground corn and 14 g/d of YC (n = 20), fed as a top-dress. Cows received the same close-up diet from 30 d prepartum until calving [1.39 Mcal/kg of dry matter (DM) and 12.3% crude protein (CP)] and lactation diet from calving to 50 DIM (1.60 Mcal/kg of DM and 15.6% CP). Blood samples and rumen fluid were collected at various time points from -30 to 50 d relative to calving. Cows fed YC compared with control showed a trend for increased energy-corrected milk (+3.2 kg/d). Lower somatic cell counts were observed in YC cows than in control. We detected a treatment × time interaction in nonesterified fatty acids (NEFA) that could be attributed to a trend for greater NEFA in YC cows than control at 7 DIM, followed by lower NEFA in YC cows than control at 14 and 30 DIM. In the rumen, YC contributed to mild changes in rumen fermentation, mainly increasing postpartal valerate while decreasing prepartal isovalerate. This was accompanied by alterations in rumen microbiota, including a greater abundance of cellulolytic (Fibrobacter succinogenes) and lactate-utilizing bacteria (Megasphaera elsdenii). These results describe the potential benefits of supplementing yeast culture during the late pregnancy through early lactation, at least in terms of rumen environment and performance.

Tannins and other phytochemicals are known to improve RUP in the diet by binding protein and then limiting ruminal degradation, which may improve milk yield and milk protein synthesis. The objective of this study was to evaluate the effects of dietary phytochemicals (tannins and Capsicum species) as rumen modifiers on production parameters and milk efficiency in dairy cows. Twenty-four multiparous Holstein cows (96 ± 16 d in milk; mean ± standard deviation) were used in a replicated 3 × 3 Latin square design balanced to measure carryover effects. Cows were blocked according to days in milk, milk production, and body weight and randomly assigned to 1 of 3 groups (n = 8/group). Each group was assigned to a unique treatment sequence across the 3 periods in the Latin square. The experiment consisted of a 14-d covariate period and three 30-d treatment periods. Cows received a basal diet supplemented with soybean meal pellets (SB) as the control diet, phytochemicals (RUM; Rumiviv, CCPA, Janzé, France) pelleted with soybean meal, or expeller soybean meal (ESBM; SoyPlus, West Central Soy, Ralston, IA). Milk production and dry matter intake during the last 4 d of each period were used for statistical analysis. Blood and rumen fluid samples were collected on d 27 of each period. Rumen fluid was analyzed for ammonia N and volatile fatty acids as well as ruminal bacteria via quantitative PCR amplification of 16S ribosomal DNA genes. Greater milk yield (37.9 vs. 36 kg/d), energy-corrected milk (39.7 vs 37.1 kg/d), and protein yield (1.15 vs. 1.08 kg/d) were observed in RUM compared with SB, but these parameters were similar between RUM and ESBM. Concentrations of total volatile fatty acids (118.1 vs. 101.5 mM) were greater in RUM in comparison to SB and ESBM diets. Cows fed RUM had greater β-hydroxybutyrate (0.49 vs. 0.42 mmol/L) than SB and ESBM. Selenomonas ruminantium, Succinimonas amylolytica, and Streptococcus bovis in rumen fluid were lower in RUM fed cows in comparison to SB and ESBM. Increased total volatile fatty acids and lower ruminal abundance of bacteria associated with low feed efficiency in RUM cows can partially explain the improvements observed in milk yield and milk efficiency. Overall, these data suggest that feeding a combination of tannin mixture and Capsicum can significantly affect rumen fermentation characteristics via partial manipulation of rumen microbiota, and these effects were reflected in improved milk production and efficiency.

The continuous trend for a narrowing margin between feed cost and milk prices across dairy farms in the United States highlights the need to improve and maintain feed efficiency. Yeast culture products are alternative supplements that have been evaluated in terms of milk performance and feed efficiency; however, less is known about their potential effects on altering rumen microbial populations and consequently rumen fermentation. Therefore, the objective of this study was to evaluate the effect of yeast culture supplementation on lactation performance, rumen fermentation profile, and abundance of major species of ruminal bacteria in lactating dairy cows. Forty mid-lactation Holstein dairy cows (121 ± 43 days in milk; mean ± standard deviation; 32 multiparous and 8 primiparous) were used in a randomized complete block design with a 7-d adaptation period followed by a 60-d treatment period. Cows were blocked by parity, days in milk, and previous lactation milk yield and assigned to a basal total mixed ration (TMR; 1.6 Mcal/kg of dry matter, 14.6% crude protein, 21.5% starch, and 38.4% neutral detergent fiber) plus 114 g/d of ground corn (CON; n = 20) or basal TMR plus 100 g/d of ground corn and 14 g/d of yeast culture (YC; n = 20; Culture Classic HD, Cellerate Yeast Solutions, Phibro Animal Health Corp.). Treatments were top-dressed over the TMR once a day. Cows were individually fed 1 × /d throughout the trial. Blood and rumen fluid samples were collected in a subset of cows (n = 10/treatment) at 0, 30, and 60 d of the treatment period. Rumen fluid sampled via esophageal tubing was analyzed for ammonia-N, volatile fatty acids (VFA), and ruminal bacteria populations via quantitative PCR amplification of 16S ribosomal DNA genes. Milk yield was not affected by treatment effects. Energy balance was lower in YC cows than CON, which was partially explain by the trend for lower dry matter intake as % body weight in YC cows than CON. Cows fed YC had greater overall ruminal pH and greater total VFA (mM) at 60 d of treatment period. There was a contrasting greater molar proportion of isovalerate and lower acetate proportion in YC-fed cows compared with CON cows. Although the ruminal abundance of specific fiber-digesting bacteria, including Eubacterium ruminantium and Ruminococcus flavefaciens, was increased in YC cows, others such as Fibrobacter succinogenes were decreased. The abundance of amylolytic bacteria such as Ruminobacter amylophilus and Succinimonas amylolytica were decreased in YC cows than CON. Our results indicate that the yeast culture supplementation seems to promote some specific fiber-digesting bacteria while decreasing amylolytic bacteria, which might have partially promoted more neutral rumen pH, greater total VFA, and isovalerate.

Maternal metabolic disruptions, such as ketosis, can have adverse effects on fetal development and influence postnatal factors. Twelve Holstein calves were randomly enrolled in this study at birth and monitored until 8 weeks of age. The study was conducted from fall 2018 until spring 2019. After completing the data collection period, calves were classified according to their respective dams ketotic condition after parturition. This classification was based on dam blood β-hydroxybutyrate < 1.4 mmol/L nonketotic (NONKET; n = 6 calves) or ≥1.4 mmol/L subclinical-ketotic (SK; n = 6 calves). SK calves had greater birth body weight (p = 0.05) but exhibited a slower growth rate compared to NONKET calves from 1 to 8 weeks (p = 0.02). At birth, SK calves had lower (p < 0.01) levels of non-esterified fatty acids and bilirubin compared to NONKET calves. Analysis of feces alpha diversity indicates that by 3 weeks, NONKET calves had greater diversity, richness, and evenness. Butyricicoccus pullicaecorum and Gallibacterium anatis were more abundant in SK calves (p < 0.05) at 3 weeks. In contrast, NONKET calves had a greater (p < 0.05) abundance of Sharpae azabuensis at 3 weeks. These findings suggest that subclinical ketosis in cows can impact the in-utero development, postnatal growth, and maturing gut microbiome of their offspring.

This study evaluated the effects of feeding a commercial yeast culture on blood biomarkers and polymorphonuclear leukocyte (PMNL) gene expression in dairy cows during the transition period until 50 d postpartum. Forty Holstein dairy cows were used in a randomized complete block design from −30 to 50 d. At −30 d, cows were assigned to a basal diet plus 114 g/d of top-dressed ground corn (control; n = 20) or 100 g/d of ground corn and 14 g/d of a yeast culture product (YC; n = 20). Blood samples were collected at various time points from −30 to 30 DIM to evaluate blood biomarkers and PMNL gene expression related to inflammation, liver function, and immune response. Liver function biomarkers, gamma-glutamyl transferase (GGT) and albumin were greater and lower, respectively, in YC cows in comparison to control. However, these biomarkers remained within physiological levels, indicating an active inflammatory process. Genes in PMNL expression related to inflammation (NFKB1, TNFA, TRAF6), anti-inflammation (IL10), and cell membrane receptors (SELL) were upregulated in the YC group in comparison to control. These results suggest that YC could stimulate a more active inflammatory response with signs of a resolution of inflammation in transition cows.

RESUMO Objetivou-se avaliar as alterações fisiológicas de ovinos submetidos à restrição alimentar, expostos à radiação solar e à sombra. Dez borregas mestiças foram divididas igualmente em dois grupos: grupo radiação solar - GRS, animais expostos ao sol durante o dia; e grupo sombra - GS, animais alocados dentro de um galpão à sombra. Nos seis dias iniciais de experimento, os animais foram submetidos à restrição alimentar, com acesso apenas à água, já expostos ao sol ou à sombra. Nos seis dias subsequentes, foi ofertada dieta composta por ração e feno de alfafa (3%PV). Os parâmetros avaliados foram frequência respiratória (FR), temperatura retal (TR), β-hidroxibutirato (BHB), pH urinário, ingestão de matéria seca (IMS) e dados bioclimáticos (temperatura, umidade relativa do ar e índice de temperatura e umidade - ITU). A FR foi o parâmetro em que houve maior diferença significativa entre os grupos (p0,8mmol/L; pH<7,0). Ovelhas que sofrem restrição alimentar durante períodos de alta temperatura e umidade têm menor frequência respiratória e temperatura interna, independentemente de estar na sombra ou pleno sol. Porém, quando normalizado a oferta de alimento as ovelhas em pleno sol têm menor ingestão de matéria seca.