Rumen Fermentation Characteristics Require More Time to Stabilize When Diet Shifts

Effect of replacing corn straw by sweet sorghum silage or whole plant corn silage in sheep diets on rumen fermentation and bacterial flora

Sweet sorghum silage (SS; Sorghum dochna 'Dochna') has been extensively studied in recent years as a supplementary forage-to-corn silage (CS; Zea mays L.), but there are still relatively few studies on its effects on the rumen environment of sheep. Determining the short-term impact of converting roughage from corn straws to SS compared to CS on rumen fermentation and bacterial population dynamics was the main goal of the current study. Twelve female thin-tailed Han sheep (29.8 ± 1.34 kg) were randomly divided into one of two treatments: concentrate supplemented with SS or CS, respectively. During the 15-day pretest period, concentrate was fed in two separate feedings at 0800 h and 1800 h, and ensure that the animals were all consumed within an hour of being fed. Thereafter, the animals had free access to corn straw. The feeding procedures during the pretest period were the same as during the measurement period. Rumen fluid was collected via sheep esophageal tube on the last day of adaptation phase (1-7 days) and stabilisation phase (8-30 days), respectively. The results showed that there was a similarity in the total concentration of VFA (volatile fatty acid) and the proportions of acetate, propionate, butyrate, and branched-chain VFA (P > 0.05) and microbial diversity indices (P > 0.05) between the two silage groups throughout the experimental period. The concentration of Ammonia nitrogen (P = 0.001) and proportion of valerate (P = 0.028) decreased in the CS and SS groups, respectively. The abundance and predicted function of rumen bacteria in the SS group did not differ significantly (P > 0.05) between the two measurement phases. However, the abundance of Prevotella_1 (P = 0.038) was higher in the CS group than in the SS group at 7 d. The abundances of Firmicutes (P = 0.005) and Ruminococcaceae_NK4A214_group (P = 0.002) increased, while the abundances of Bacteroidetes (P = 0.044), Proteobacteria (P = 0.046), and Prevotella_1 (P = 0.009) decreased in the CS group at 30 d. Genes related to pyruvate metabolism (P = 0.020) were significantly higher at 30 d than at 7 d, whereas purine metabolism (P = 0.007), pyrimidine metabolism (P = 0.007), and metabolic pathways (P = 0.010) were lower at 30 d in the CS group. In conclusion, this study indicated that SS maintained a steady rumen environment, while CS caused high fluctuations in bacterial abundance and predicted function for sheep.

Active dry yeast supplementation benefits ruminal fermentation, bacterial community, blood immunoglobulins, and growth performance in young dairy goats, but not for intermittent supplementation

This study evaluated the effects of active dry yeast (ADY) supplementation and supplementation strategies on ruminal fermentation, bacterial community, blood metabolites, and growth performance in young dairy goats. Sixty young female Guanzhong dairy goats of similar age (4.00 ± 0.50 months) and BW (19.65 ± 0.41 kg) were randomly divided into 3 groups (n = 20): (1) basal diet group (CON); (2) basal diet continuously supplemented with 3.0 g/goat per day commercial ADY (a proprietary strain of Saccharomyces cerevisiae with 5.0 × 10⁹ cfu/g) group (CSY); (3) basal diet with intermittently supplemented ADY group (ISY; 5 d supplementation with ADY at 4.5 g/goat per day following 5 d of no supplementation). The experiment lasted 67 d with the first 7 d as an adaptive period. Rumen fluid and blood samples were collected bi-weekly. Data were analyzed using the MIXED procedure combined with the SLICE option in SAS. Specific orthogonal contrasts of ADY vs. CON and CSY vs. ISY were also analyzed. During the experimental period, ADY supplementation resulted in greater DMI (P = 0.03), ruminal acetate proportion (P < 0.01) and acetylesterase activity (P = 0.01), and blood contents of glucose (P = 0.01) and IgM (P = 0.02) and tended to have greater ADG (P = 0.05) and paunch girth (P = 0.06) than the CON, despite the propionate proportion (P = 0.03) and contents of total protein (P = 0.04) and IgA (P = 0.03) being lower. The lower ruminal NH₃-N (P < 0.01) and blood urea nitrogen (P = 0.07) contents indicated greater nitrogen utilization with ADY supplementation. ADY supplementation showed persistent effects after it was stopped because the BW at 12 months of age (P = 0.03) and birth weight of lambs (P = 0.02) were greater than the CON. However, the ISY did not show those benefits and had significantly lower relative abundances of fiber-degrading related bacteria than the CSY. In conclusion, ADY supplementation, especially continuously supplemented, may enhance ADG and ADG:DMI ratio by improving DMI, ruminal cellulolytic bacteria abundance and enzyme activity, nitrogen utilization, and immune status. These findings provide a theoretical basis for the rational application of ADY and have important practical implications for the design of nutritional strategies in growing dairy goats.

Changes in in vitro rumen fermentation parameters of crossbred cattle (Bos taurus) and buffalo (Bubalus bubalis) in response to diet at different time intervals

Assessment of the diet adaptation period is critical for feeding experiments in ruminants to have significant changes in the concerned parameters. An in vitro trial was conducted to investigate the impact of the sampling at different time periods (day 0, 11, 21, and 60) to determine the adaptation period of feed treatment over the ruminal fermentation parameters in crossbred Karan-Fries cattle (Bos taurus) and Murrah (Bubalus bubalis) heifers. Two types of total mixed rations (TMRs), viz. high forage diet (HFD) having roughage and concentrate ratio (R:C) as 70:30 and high concentrate diet (HCD) having R:C as 40:60 were formulated, and fed to cattle and heifers. Rumen liquors were collected from all the animals on 0, 11, 21, and 60 days. HFD and HCD diets were incubated with strained rumen liquor collected from cattle and buffalo adopting Menke’s in vitro gas procedure. The results showed that most of the in vitro rumen fermentation parameters, viz. total volatile fatty acids (TVFAs) (mM/ml), acetate (%), propionate (%), butyrate (%), acetate propionate ratio (A:P), partitioning factor (PF) and microbial biomass production (MBP) (mg), in vitro dry matter digestibility (IVDMD) (%) and in vitro organic matter digestibility (IVOMD) (%) were significantly different at day 0 and 11 compared to day 21. Afterward, up to day 60, there were no effects reported except increased IVDMD and IVOMD for buffalo compared to day 21. As a result of our findings, it can be concluded that there are significant differences in rumen fermentation parameters at 11 and 21 days and that the time period for cattle and buffalo should not be reduced to 11 days from 21 days in order to achieve proper feed adaptation and stabilize the rumen fermentation process. Further research is needed to investigate the impacts of the adaption period at various time intervals.