Effects of extruded soybeans and forage source on fermentation by rumen microorganisms in continuous culture.

Continuous culture fermenters were used to evaluate effects of extrusion of whole soybeans and changes in forage composition of diets on microbial fermentation. Treatments were arranged in a 2 x 4 factorial design with soybeans (raw or extruded) and dietary treatment (ratio of alfalfa hay to corn silage; 82:18, 61:39, 43:57, and 27:73 of dietary forage) as main effects. Soybeans constituted 9.6, 14.4, 19.2, and 23.9% of DM for each of the respective dietary treatments. True digestion of DM, ADF, and NDF was unaffected by processing of soybeans or dietary treatment, but true digestion of OM decreased as concentration of corn silage and soybeans increased. Total VFA concentration was unaffected by source of soybeans or dietary treatments; however, molar concentration of butyrate decreased in fermenters supplied with diets containing extruded soybeans. Degradation of CP was not influenced by soybean source but decreased as the concentration of corn silage and soybeans increased. Bacterial N output decreased, and dietary N flow from the fermenters increased, as concentration of corn silage and soybeans increased. Changes in the ratio of alfalfa hay to corn silage and alteration of dietary soybean concentration affected true OM digestion and dietary CP degradation, but extrusion of whole soybeans had little effect on fermentation.

Effect of ruminal protein degradation of blood meal and feather meal on the intestinal amino acid supply to lactating cows.

Four lactating cows fitted with ruminal cannulae and T-type cannulae in the proximal duodenum and terminal ileum were utilized to measure protein degradation in the rumen and amino acid flow to and absorption from the small intestine. Soybean meal, blood meal, feather meal, and a 50-50 combination of blood meal and feather meal provided 50% of the protein in diets that contained 50% grain mix, 40% corn silage, and 10% alfalfa pellets on a DM basis. Ruminal degradation of dietary CP was 53, 43, 32, and 37% for diets containing soybean meal, blood meal, feather meal, and the combination of meals. Cows fed the latter two diets also had lower ruminal NH3 concentrations and efficiency of bacterial protein synthesis compared to those fed the soybean meal diet. Total tract N digestibility was lower for diets containing feather meal (63.4%) and a combination of meals (66.3%) than the soybean meal diet (78.5%). Total amino acid flow to the duodenum was 19.3 and 15.6% higher for cows fed the feather meal and combined meal diets, respectively, compared with the soybean meal diet. Total amino acid absorption from the small intestine was higher as well as absorption of individual amino acids for the combined meal diet compared with the soybean meal diet. Absorption of individual amino acids, expressed as a percentage entering the duodenum, was lowest for the feather meal diet. Results from this study show that feeding a combination of blood meal and feather meal instead of soybean meal can increase intestinal supply and absorption of amino acids in dairy cattle.

Lactational response to soybean meal, heated soybean meal, and extruded soybeans with ruminally protected methionine.

Seventy-three high producing Holstein cows were arranged in a 3 X 2 factorial to evaluate three protein supplements (soybean meal, heat-treated soybean meal, and extruded blend of soybeans and soybean meal) without or with 15 g/head/d of ruminally protected DL-methionine during wk 4 through 16 postpartum. Total mixed diets contained (DM basis) 30% corn silage, 15% alfalfa hay, and 55% of the respective concentrate mix. Milk production was higher when cows were fed either heated soybean product instead of soybean meal. Methionine supplementation increased production when fed with soybean meal (32.2 and 33.8 kg/d) but not when fed with heat-treated soybean meal (34.5 and 33.0 kg/d) or extruded soybeans (36.2 and 34.4 kg/d). Milk fat percentages were lower with extruded soybeans (3.01, 2.93, and 2.66) and were similar without (2.83) or with (2.90) supplemental methionine. Milk protein percentages were highest when fed soybean meal, lowest with extruded soybeans (3.02, 2.92, and 2.87), and higher with supplemental methionine (2.91 and 2.96). Dry matter intake was higher when fed supplemental methionine (20.0 and 21.3 kg/d). Production of milk in early lactation high producing dairy cows was increased by supplementing a soybean meal diet with ruminally protected methionine or by replacing the soybean meal with heat-treated soybean meal, soybeans, or a mixture of the two.

Chickpeas as a substitute for corn and soybean meal in growing heifer diets.

Twelve Holstein heifers (average weight 270 kg) were randomly assigned to one of four diets to evaluate the feeding value of chickpeas. Total mixed diets were composed of (dry matter) 40% concentrate mix, 24.5% chopped alfalfa hay, and 35.5% corn silage. Concentrate mixes contained 0, 25, 50, and 75% chickpeas in place of corn and soybean meal. Diets were fed individually for 80 d. Average daily gains (.98, 1.13, 1.14, and .95 kg) were higher for heifers fed 25 and 50% chickpeas than for those fed 0 and 75% chickpeas. Feed per gain (4.72, 4.05, 3.65, and 4.01 kg/kg) was lower for all diets containing chickpeas. Dry matter intake was lowest for heifers fed 75% chickpeas, and dry matter intake as percent of body weight was similar for all groups. Ruminal ammonia, pH, total volatile fatty acid concentrations, and ratio of acetate to propionate were similar for all diets. Serum urea and rumen parameters displayed no trends between diets. Chickpeas were an acceptable replacement for corn and soybean meal in growing heifer diets.

Responses to controlling gastrointestinal parasitism in dairy cattle.

Sixty-eight Holstein heifers, paired on milk production potential and season of birth, were randomly assigned within pairs to a control or treatment group to evaluate the effect of raising replacement heifers on a prophylactic anthelmintic regimen. The anthelmintic, thiabendazole (6.6 g/100 kg body weight), was administered orally as a paste at 2.5, 3.5, 6, 9, and 14 mo of age and at parturition. The control group received no thiabendazole. Fecal samples were collected from both groups at the time of thiabendazole treatment. Days to first service were 457.1 and 457.8 for the control and treatment groups. There were no differences in services per conception or days to first calving. Nematode eggs per 5 g of feces were similar at 2.5 mo (.6 and .8), 3.5 mo (38.6 and 22.4), 6 mo (40.2 and 43.1), 9 mo (39.0 and 22.4), 14 mo (55.2 and 22.4), or parturition (16.5 and .4). There were no differences in body weight changes over the first 18 mo of age. Subsequent first lactations were similar (9422 and 8710 kg 305-d mature equivalent, for twice daily milking) as was actual milk production for the first 120 d of lactation. Under these environmental conditions and apparently low parasitism in this herd, thiabendazole did not substantially influence nematode egg count and had no effects on body weight gains or milk production.