Rumen-protected l-carnitine supplementation during mating period altered metabolic status and reproductive performance of ewes.

Current study hypothesized that dietary l-carnitine (LC) inclusion during the mating period ameliorates both metabolic status and reproductive performance of ewes. Seventy Baluchi ewes (52 ± 4.2 kg of bodyweight and 18 ± 6 months old of age) were enrolled in this study. Animals were randomly allocated into two dietary treatments, control (only basal diet) or basal diet plus supplementation with a rumen-protected LC (Carneon 20 Rumin-pro; 20% LC; Kaesler Nutrition GmbH) at the rate of 10 g/head/day from 21 days before until 35 days after introducing rams to the ewes (MP). Feed intake was monitored by subtracting the ort from feed offered. Blood sample collection was conducted on Days -10, +10 and +20 relative to MP. Pregnancy was confirmed on Day 30 post-MP. Feed intake of the ewes in the LC group was higher than the control (p < 0.05). LC supplementation increased the cholesterol concentration in the ewes (p < 0.05). Blood urea concentration of animals in the LC group was significantly lower than the control (p < 0.05). The mRNA expression of toll-like receptor 4 was evidently lower in animals supplemented with LC than the control (p < 0.05). Both lambing and fecundity rates in the LC group tended to be higher compared with the control. LC supplementation showed potential to alter certain metabolites in the ewes. A tendency for higher lambing rate may partly be driven by dams efficient energy partitioning to support foetal growth and maintaining pregnancy.

Variations in fecal pH and fecal particle size due to changes in dietary starch: Their potential as an on-farm tool for assessing the risk of ruminal acidosis in dairy cattle.

This study evaluated the variations in fecal pH and particle size due to changes in dietary starch, and the potential of these variations as a tool to detect the risk of subacute ruminal acidosis (SARA) in dairy cows. Nine ruminally cannulated, non-lactating, non-pregnant Holstein cows were used in two 6-week experimental periods. In each period, cows were first fed a forage diet for 1 wk., then transitioned over 1 wk. to a 65% concentrate ration, which they consumed for 4 wk. continuously. Measurements were conducted when cows consumed 17.3, 21.9 and 28.8% dietary starch. Fecal pH and particle size were measured at 0, 4, 8 and 12 h relative to feeding in days 7, 11, 21, 28, 35, and 42 of each period. Ruminal pH was measured every 15 min. Data were analyzed with SAS, the statistical model included concentrate level, time of sampling and period as fixed effects and cow was considered as random effect. Data showed an interaction between dietary starch level and time relative to feeding on fecal pH, with a shift in its pattern due to diet change. Specifically, during low starch feeding (17.3%), fecal pH was highest before feeding and decreased thereafter, reaching lowest value 12 h post-feeding (P < 0.05). With the 21.9% starch diet, fecal pH did not change significantly after feeding. However, during high starch feeding (28.8%), fecal pH decreased, being lowest before feeding and increased (P < 0.05) during the day reaching highest values at 8 and 12 h post-feeding. Fecal pH was lower (P < 0.01) during the days of high starch feeding; though, it was maintained relatively stable through this timeframe. Increasing dietary starch decreased the proportion of small fecal particles (0.5 to 1.18 mm), but increased the proportion of large (>1.18 mm) and soluble particles (<0.5 mm). There were significant correlations among ruminal pH, fecal pH and fecal particle size of feces collected before feeding. For example, fecal pH was correlated with minimum and daily mean ruminal pH; the proportion of fecal particles 0.5 to 1.18 mm correlated with minimum and daily mean ruminal pH (P < 0.01). Log-linear dependency analyses indicated a strong effect of starch intake on fecal pH so that for every kg increase in starch intake, there was a reduction in fecal pH by 0.38 units. In addition, regression analysis showed that the proportion of fecal particles between 0.5 and 1.18 mm showed strong dependency on the ratio dietary physically effective fiber to starch (P < 0.01). Ruminal pH also correlated with fecal particle size of frozen/thawed samples, but with lower strength than fresh samples. Overall, evaluating variations of fecal pH and particle size holds potential as a non-invasive on-farm tool for assessing rumen pH and SARA risk.

Characterization of microbial intolerances and ruminal dysbiosis towards different dietary carbohydrate sources using an in vitro model.

AIM: This study aimed to characterize the critical points for determining the development of dysbiosis associated with feed intolerances and ruminal acidosis. METHODS AND RESULTS: A metabologenomics approach was used to characterize dynamic microbial and metabolomics shifts using the rumen simulation technique (RUSITEC) by feeding native cornstarch (ST), chemically modified cornstarch (CMS), or sucrose (SU). SU and CMS elicited the most drastic changes as rapidly as 4 h after feeding. This was accompanied by a swift accumulation of d-lactate, and the decline of benzoic and malonic acid. A consistent increase in Bifidobacterium and Lactobacillus as well as a decrease in fibrolytic bacteria was observed for both CMS and ST after 24 h, indicating intolerances within the fibre degrading populations. However, an increase in Lactobacillus was already evident in SU after 8 h. An inverse relationship between Fibrobacter and Bifidobacterium was observed in ST. In fact, Fibrobacter was positively correlated with several short-chain fatty acids, while Lactobacillus was positively correlated with lactic acid, hexoses, hexose-phosphates, pentose phosphate pathway (PENTOSE-P-PWY), and heterolactic fermentation (P122-PWY). CONCLUSIONS: The feeding of sucrose and modified starches, followed by native cornstarch, had a strong disruptive effect in the ruminal microbial community. Feed intolerances were shown to develop at different rates based on the availability of glucose for ruminal microorganisms. SIGNIFICANCE AND IMPACT OF THE STUDY: These results can be used to establish patterns of early dysbiosis (biomarkers) and develop strategies for preventing undesirable shifts in the ruminal microbial ecosystem.