Effects of dietary inclusion of dry distillers grains with solubles on performance, carcass characteristics, and nitrogen metabolism in meat sheep: a meta-analysis

We conducted a meta-analysis in this scientific study to determine the effects of feeding meat sheep dry distillers grains with solubles (DDGS). Thirty-three peer-reviewed articles that met our inclusion requirements and were published between 1997 and 2021 were examined. To calculate the variation in performance, fermentation, carcass features, and nitrogen efficiency between the DDGS and control (no DDGS) treatments, we used 940 sheep weighing an average of 29.1 ± 1.5 kg. We used a hierarchical mixed model to conduct a meta-regression, subset, and dose-response analysis, while taking into consideration categorical variables like breed (pure or cross-breed), and continuous factors, like CP, NDF, and DDGS inclusion rate. Our findings indicate that sheep fed DDGS had higher (p < 0.05) final body weight (51.4 vs. 50.4 kg), neutral detergent fiber digestibility (55.9 vs. 53.8%), and total-tract ether extract digestibility (81.7 vs. 78.7%) than sheep on a control diet. No effects were observed on DMI, CP, and rumen fermentation, but dietary DDGS tended to increase (p = 0.07) HC weight (25.53 vs. 24.6 kg) and meat (redness) color (16.6 vs. 16.3) among treatment comparisons. Dietary DDGS was associated with higher N intake (29.9 vs. 26.8 g/d), fecal N (8.2 vs. 7.8 g/d), and digestibility (71.9 vs. 68.5%). Urinary nitrogen was significantly (p < 0.05) affected linearly by increasing the intake of DDGS in the diet. Based on the dose-response analysis, dietary DDGS inclusion should not exceed 20% to avoid negative effects on performance, nitrogen metabolism, and meat color. Dietary protein from DDGS should not exceed 17% to prevent reduced TVFA concentrations. Breed strongly influenced (p < 0.05) RMD in performance, and inconsistent responses were observed between crossbreed and purebred sheep comparisons. Despite these inconsistencies, no publication bias was observed, but a high variance (Ω²) among comparisons-between-studies was detected. This meta-analysis showed evidence in support of the hypothesis that feeding meat sheep DDGS at a rate of 20% can improve their performance, digestibility, carcass weight, and meat color.

A revised representation of ruminal pH and digestive reparameterization of the Molly cow model

Ruminal pH is a critical factor to regulate nutrient degradation and fermentation. However, it has been poorly predicted in the Molly cow model, and recent improvements in the representation of nitrogen cycling across the rumen wall altered some of the modeled responses to feed nutrients, resulting in some model bias. The objectives of this study were to further improve the representation of pH and to refit parameters related to ruminal metabolism and nutrient digestion in the model to resolve this bias, and to use the improved model to estimate nitrogen and energy fluxes with varying rumen-degradable protein (RDP; 40 vs. 60%) and ruminally degraded starch (RDSt; 50 vs. 75%). A meta data set containing 284 peer reviewed studies with 1,223 treatment means was used to derive parameter estimates for ruminal metabolism and nutrient digestions. Refitting the parameters significantly improved the accuracy and precision of the model predictions for ruminal nutrient outflow [acid detergent fiber (ADF), neutral detergent fiber (NDF), total N, microbial N, nonammonia N, and nonammonia nonmicrobial N], ammonia and blood urea concentrations, and fecal nutrient outflow (protein, ADF, and NDF). The prediction error for body weight was decreased from 19.3 to 6.2% with decreased mean bias (from 76.0 to 11.5%) and slope bias (from 17.2 to 7.7%), primarily due to improved representations of ruminal dry matter and liquid pool size. Adding ammonia concentration as a driver to the pH equation increased the precision of predicted ruminal pH and, thereby, the precision of predicted volatile fatty acid (VFA) concentrations, due to improved representation of pH regulation of VFA production rates. Although minor mean and slope bias were observed for ruminal pH and VFA concentrations, the concordance correlation coefficients indicated that much of the observed variation in these variables remains unexplained. Overall, the biological functions of nutrient degradation and digestion appear to be represented without bias. Simulated results indicated that decreasing RDP and RDSt proportions in an isonitrogenous and isocaloric diet can slightly improve N efficiency, and increasing RDSt proportions can increase energy efficiency.

Invited Review: Ethanol co-products for dairy cows: there goes our starch … now what?

Paz, H. A., Castillo-Lopez, E., Ramirez-Ramirez, H. A., Christensen, D. A., Klopfenstein, T. J. and Kononoff, P. J. 2013. Invited Review: Ethanol co-products for dairy cows: there goes our starch … now what? Can. J. Anim. Sci. 93: 407–425. The rise of the grain-ethanol industry has resulted in a dramatic increase in the availability of feed co-products namely, distillers’ grains with solubles (DG). The cost of feeds that have traditionally been used for energy continues to increase and there is a need to understand the potential impact of replacing these feeds with DG on milk yield and composition. Using the Dairy National Research Council (2001) model and data from a total of 25 published studies (81 observations), we used a meta-analytical procedure to evaluate the impact of feeding corn milling co-products on lactating dairy cows. Based on our model, the inclusion of DG did not affect dry matter intake (P=0.35) but a trend for an increase in milk yield was observed (P=0. 10). Additionally, the percentages of milk fat and protein in the milk were not affected (P=0.24 and 0.25, respectively). The modeled daily rumen outflow of Lys in grams was significantly (P<0.01) reduced and Met was not affected (P=0.79) when DG were included. The error associated with net energy of lactation allowable milk averaged 5.0±1.0 kg d−1and was not affected by DG (P=0.79) but the error associated with metabolizable protein allowable milk tended (P=0.10) to be higher for cows consuming DG by 1.4±1.2 kg d−1.

Antioxidant and anticholinesterase effects of frequently consumed cereal grains using in vitro test models

The ethyl acetate and ethanol extracts obtained from eight varieties (Faikbey, Y-1779, CI-8357, Cheokota, Seydişehir, Y-330, Sivas and YVD-18) of oat (Avena sativa L.), one variety (Larende) of barley (Hordeum vulgare L.), one variety (Tatlicak 97) of triticale (Triticale sp.) and one rye variety (Aslim 95) (Secale cereale L.) were investigated for their antioxidant effects in seven test systems. Anticholinesterase activity of the extracts was examined by enzyme-linked immunosorbent assay (ELISA) microplate reader. Total phenol and flavonoid contents were calculated using Folin Ciocalteau and AlCl₃ reagents, respectively. All of the extracts were ineffective in cholinesterase inhibition assays and had weak-to-moderate activity in antioxidant assays. The extracts exerted better activity in iron-chelation capacity ranging between 43.17 ± 2.04 and 62.97 ± 1.29%. Triticale extracts showed higher activity in reducing power experiments. A notable difference in the results of the antioxidant activity assays was observed among the oat varieties.