The objective of this study was to evaluate the effects of dietary fat supplementation on dry dairy cows feed intake, digestion, ruminal kinetics, biohydrogenation, and abomasal flow of fatty acids (FAs). Eight Holstein rumen and abomasum fistulated dry cows (average body weight of 614 ± 59 kg), were assigned to a replicated 4 × 4 Latin square design experiment, with 21-d periods. The experimental diets were: 1) control (CON): corn-and soybean meal-based diet, with no fat source; 2) soybean oil (SO) diet with 30 g/kg dry matter (DM) of soybean oil; 3) whole raw soybean (WS) diet with 160 g/kg DM of whole raw soybean grain; 4) calcium salts of fatty acids (CS) diet with 32 g/kg DM of calcium salts of unsaturated FA. Fat-supplemented diets increased ether extract intake and digestibility without affecting DM intake. However, these diets promoted a decrease in DM and neutral-detergent fiber (NDF) total tract apparent digestibility. Fat sources decreased ruminal acetate to propionate ratio (C2:C3). In addition, SO diet increased ruminal propionate concentration and decreased C2:C3 in relation to protected sources of FA (CS and WS). Furthermore, cows fed CS diet exhibited higher ruminal pH, NH 3-N and acetate concentration compared to those fed WS diet. Fatty acid supplementation did not alter serum glucose and urea concentration, but increased the serum cholesterol concentration. Although FA supplementation increased net energy intake of cows, energy and nitrogen balances, and microbial protein synthesis were not affected by the experimental diets. Fat supplementation had no effect on ruminal digestion neither on DM and NDF passage rates. Cows fed CS and WS diets presented higher DM and NDF ruminal digestion rates whether compared to SO one. Consequently, cows fed CS and WS had higher truly digestible NDF ruminal removal rate than those fed SO. Calcium salts of unsaturated FA increased DM and NDF rumen passage rate and decreased
Ruminants have a unique metabolism and digestion of unsaturated fatty acids (UFA). Unlike monogastric animals, the fatty acid (FA) profile ingested by ruminants is not the same as that reaching the small intestine. The objective of this study was to evaluate whole raw soybeans (WS) in diets as a replacer for calcium salts of fatty acids (CSFA) in terms of UFA profile in the abomasal digesta of early- to mid-lactation cows. Eight Holstein cows (80 ± 20 d in milk, 22.9 ± 0.69 kg/d of milk yield, and 580 ± 20 kg of body weight; mean ± standard deviation) with ruminal and abomasal cannulas were used in a 4 × 4 Latin square experiment with 22-d periods. The experiment evaluated different fat sources rich in linoleic acid on ruminal kinetics, ruminal fermentation, FA abomasal flow, and milk FA profile of cows assigned to treatment sequences containing a control (CON), with no fat source; soybean oil, added at 2.68% of diet dry matter (DM); WS, addition of WS at 14.3% of diet DM; and CSFA, addition of CSFA at 2.68% of diet DM. Dietary fat supplementation had no effect on nutrient intake and digestibility, with the exception of ether extract. Cows fed fat sources tended to have lower milk fat concentration than those fed CON. In general, diets containing fat sources tended to decrease ruminal neutral detergent fiber digestibility in relation to CON. Cows fed WS had lower ruminal digestibility of DM and higher abomasal flow of DM in comparison to cows fed CSFA. As expected, diets containing fat supplements increased FA abomasal flow of C18:0 and total FA. Cows fed WS tended to present a higher concentration of UFA in milk when compared with those fed CSFA. This study suggests that under some circumstances, abomasal flow of UFA in early lactation cows can be increased by supplementing their diet with fat supplements rich in linoleic acid, regardless of rumen protection, with small effects on ruminal DM digestibility.
The aim of the present study was to evaluate effects of partial replacement of corn grain and soybean meal with whole raw soybean or whole cottonseed on milk yield and composition, digestibility, ruminal fermentation and blood metabolites. Eighteen multiparous Holstein cows (133.0 ± 53.1 days in milk, 585.2 ± 54.2 kg of BW and 32.22 ± 5.32 kg/day of milk) were used in six 3 × 3 Latin squares with 21-day periods. The cows were randomly assigned to receive one of the following diets: control (CT), diet without oilseed inclusion; whole soybean (WS), inclusion of 120 g/kg of whole raw soybean (diet DM basis); and whole cottonseed (WCS), inclusion of 120 g/kg of whole cottonseed (diet DM basis). Dietary supplementation with WS or WCS had no effect on milk yield and composition. DM and non-fibre carbohydrate intake were decreased in cows fed WS and WCS when compared with CT; however, WS and WCS increased ether extract intake and digestibility. The WCS decreased DM, crude protein, ether extract and non-fibre carbohydrate intake when compared with WS. Cows fed WCS had higher ruminal pH than those fed WS or CT. Cows fed WS showed higher propionate concentration than cows fed WCS. Ruminal ammonia nitrogen concentration decreased when cows were fed WS compared with those fed CT or WCS. The partial replacement of corn grain and soybean meal with WS or WCS in diets of mid-lactating dairy cows decreased DM intake and altered ruminal fermentation, but did not affect milk yield and composition.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.