Defining risk for low reticuloruminal pH during the diet transition period in a commercial feedlot in western Canada

Dried distiller's grains for feedlot Nellore cattle fed non-forage-based diets

This study aimed to evaluate intake, animal performance and carcass traits with the inclusion of corn dried distiller grains (DDGs) replacing cornmeal (Zea mays L.) in non-forage-based diets for finishing feedlot Nellore cattle. Sixty-four uncastrated Nellore cattle weighing 267.22 ± 20.4 kg and 18 ± 3 months old were distributed in 16 pens. Experimental diets were based on cornmeal, cottonseed cake, a mineral mixture and increased levels of DDG replacing cornmeal (0, 10, 20 and 30% on a dry matter basis). The study lasted 135 days, and the intake of nutrients and body weight gain were monitored. At the end of the study, the animals were slaughtered to measure their carcass traits. During the first 34 days of the study, the DDG levels linearly increased dry matter intake and intake of all nutrients. In other phases of the feedlot, the DDG levels did not have any effect on DMI or ADG but caused a quadratic effect on hot carcass weight. Thus, DDG can replace cornmeal in non-forage diets fed to feedlot Nellore cattle without any negative effect on intake or animal performance.

Ruminal cellulolytic bacteria abundance leads to the variation in fatty acids in the rumen digesta and meat of fattening lambs

Ruminal cellulolytic bacteria could be a diagnostic tool for determining the subacute rumen acidosis (SARA) risk in individual ruminants; however, a limited number of studies have investigated the effects of the abundance of ruminal cellulolytic bacteria on the fatty acid (FA) composition of the rumen digesta and the muscle of sheep. Thus, the objective of this study was to evaluate the effect of the variation of rumen cellulolytic bacteria on the rumen fermentation, rumen digesta, and muscle FA composition of fattening lambs fed an identical diet. Forty-eight lambs were reared in individual units and fed a high-concentrate diet consisting of 20% forage and 80% concentrate. All lambs were adapted to diets and facilities for 14 d, and sampling was for 63 d. At the end of the experiment, the rumen fluid, rumen digesta, and longissimus dorsi were collected after slaughter for the measurement of volatile fatty acids, ruminal bacterial DNA, rumen digesta, and muscle FAs. The lambs were classified into the lower cellulolytic bacteria (LCB, n = 10) group and the higher cellulolytic bacteria (HCB, n = 10) group according to the abundance of pH-sensitive cellulolytic bacteria (Ruminococcus albus, Ruminococcus flavefaciens, Fibrobacter succinogenes, and Butyrivibrio fibrisolvens) in the rumen. Ruminal acetate concentration was positively correlated with the number of R. flavefaciens, F. Succinogenes, and B. fibrisolvens (P < 0.05, r > 0.296), whereas propionate and valerate concentrations were negatively correlated with the amount of F. succinogenes and B. fibrisolvens (P < 0.05, r > 0.348). Compared with the LCB group, the acetate (P = 0.018) as well as acetate to propionate ratio (P = 0.012) in the HCB group was higher, but the valerate ratio was lower (P = 0.002). The proportions of even-chain FAs and odd- and branched-chain fatty acid in the rumen digesta of lambs with the HCB were higher (P < 0.05), while the polyunsaturated fatty acids decreased than those in the LCB lambs (P < 0.05), but those FA proportions in the meat were similar between the two groups. The proportion of C17:0 in the meat of lambs in the HCB group was lower than that of lambs in the LCB group (P = 0.033). The proportions of conjugated linoleic acid in rumen digesta and meat were both higher in the HCB group than that in the LCB group (P = 0.046). These results indicated that the ruminal cellulolytic bacteria can alter the FA compositions in rumen digesta and further influenced the FA compositions in the meat of sheep.