Sodium bicarbonate was added to complete mixed rations to evaluate the effect of buffer addition on adaptation to high-energy rations by dairy cows in elderly lactation. Forty-five Holstein cows were assigned to one of three treatment groups: control pre- and postpartum; control prepartum, buffer postpartum; and buffer pre- and postpartum. Rations consisted of 85% chopped grass hay: 15% concentrate prepartum and 60% corn silage:40% concentrate postpartum. On day 4 postpartum, cows were switched abruptly to the postpartum ration for 9 wk. Buffered rations contained .6% sodium bicarbonate prepartum and .7% postpartum. Daily dry matter intake as a percent of body weight for cows fed buffer postpartum (3.51%) was greater than for cows fed no buffer (3.04%) of buffer pre- and postpartum (3.14%). Average production of 4% fat-corrected milk was greater for cows fed buffer postpartum and buffer pre- and postpartum (31.9 kg/day and 31.7 kg/day) than for cows fed no buffer (28.9 kg/day). Milk fat tests were not different. Cows fed the buffered rations lost body weight between wk 1 and 9 as compared to a net gain for cows fed no buffer. Cows fed buffers consumed more dry matter during wk 1 than did cows fed no buffer. Samples of rumen fluid, feces, and serum showed few differences that could be attributed to treatments. Compared to controls, cows fed sodium bicarbonate adapted to rations more rapidly postpartum as indicated by increased feed intake during the first 2 wk and by increased milk production during the first 4 wk of the trial.
Sodium bicarbonate was added to complete mixed rations to characterize physiological, metabolic, and ruminal changes immediately postpartum when dairy cows are switched abruptly from a low energy ration prepartum to a high energy ration postpartum. Twelve Holstein cows were paired and assigned randomly to either a control or buffered ration containing .8% sodium bicarbonate. Rations consisted of 50% corn silage:50% concentrate. All All cows were fed a similar dry cow ration for a minimum of 7 days prepartum and experimental rations for 2 wk beginning at parturition. Blood, feces, and urine were sampled on days 1, 2, 4, 7, 10, and 14 postpartum. Rumen fluid was sampled on days 7 and 14. Dry matter intake and milk production were 2.75% of body weight and 30.3 kg/day for cows fed buffer and 2.49% and 27.6 kg/day for cows fed control. Higher partial pressure of carbon dioxide and base excess in blood in cows fed buffer existed on days 2 and 4 postpartum than for cows fed the control ration. Cows fed buffer had higher concentrations of ruminal ammonia than cows fed control. This difference was less pronounced in blood urea nitrogen and urinary ammonia. Urine pH was higher for cows fed buffer than for control. Addition of sodium bicarbonate improved the acid-base status after abrupt change of ration and may be associated with increased dry matter intake and improved ration adaptation. Concentrations of most minerals and metabolites in blood serum did not differ between rations.
Research has shown acid insoluble ash (AIA) in feeds to be an acceptable natural marker for the determination of dry matter digestibility in sheep and steers fed diets of hay plus grain. However, in previous studies, animals were fed diets designed to ensure little or no orts. The purpose of this study was to determine the adequacy of AIA as an indicator of dry matter digestibility when sheep or dairy cows were fed ad libitum. Fecal, feed and ort samples from wethers and lactating Holstein cows from previous digestibility studies were used to determine the usefulness of AIA as an indicator of digestibility. Thirty-two wethers were fed whole corn plants or corn stover frozen and stored fresh or ensiled. Diets were fed ad libitum to ensure between 5 and 10% orts. In a second study, seven wethers and 10 lactating cows fed fed ad libitum alfalfa or orchard grass hay diets with 23% grain to ensure at least 10% orts. Correlation coefficients for digestibility determined by total collection versus AIA for wethers fed corn plants, cows fed hay diets and wethers fed hay diets were .96, .95 and .40, respectively. The low correlation for wethers fed hay was apparently due to a high quantity of orts with a variable AIA content. The range of total recovery of AIA from all animals was of total recovery of AIA from all animals was 98 to 102% when ort AIA was taken into account, and 91 to 121% when ort AIA was not taken into account. The use of AIA as a natural marker for the estimation of digestibility when diets are fed ad libitum has potential, provided that a sufficient number of animals is used and diets are adequately mixed to limit feed selection and sorting, or intake is determined and feed and orts are sampled.
and Implications Concern about the welfare of domesticated animals has increased dramatically in the United States and across many other industrialized countries. The issues involved are complex, and there is widespread disagreement both as to the extent of human responsibilities toward animals and how those responsibilities should be carried out. It is imperative that undergraduate students are aware through international educational endeavors to be able to tackle and work on these issues in their professional career. Therefore faculty in the Department of Animal Science at Iowa State University has created a new AnS 496 course to be held in the summer titled; European Perspectives on Farm Animal Welfare in England and Scotland.
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