Avaliação de coprodutos ensilados da indústria do milho em dietas de vacas em lactação

Abstract

Fibrous co-products in the feeding of ruminants contribute to the mitigation of environmental impacts and decrease the consumption of animals of digestible products by humans. The objective of this work is to evaluate the effect of the conventional substitution concentrated (constituted in its base of corn and soy bran) by concentrate constituted by co-products of the corn industry in lactating cows ration on the consumption of dry matter (DMI), production of milk, milk components, selectivity behavior, digestibility, blood and ruminal parameters. The statistical design used was a 2x2 cross-over with two effects differentiated by the concentrated resource (conventional concentrate and concentrate consisting of corn by-products) in two 22-day experimental ones, with 14 days of adaptation for use and eight final days of data collection. Ten crossbred lactation cows (Holstein x Jerseys) were used, distributed five in each treatment and balanced in the orders according to the calving order, days in lactation and milk production. The data were analyzed by the PROC MIXED of the SAS, considering the statistical model of random effect by cow and fixed treatment effect and period at the level of significance P <0.05 and trend 0.05≤P≤0.10. The DMI and DMO were statistically higher (P=0.005 and P=0.008) for control group, while the NDF consumption did not differ statistically (P=0.76) and the consumption of physically effective fiber was statistically higher (P<0.0001) for treatment with co-products. The production of milk, protein, casein and lactose in milk in percentage and production per day were statistically higher (P<0.01) in treatment control, while the fat in kg/day did not differ statistically (P=0.35), the production of fat and urea nitrogen in milk was higher (P=0.001 and P=0.007) in the treatment with co-products. As the dry matter digestibilities, organic matter and NDF did not differ statistically (P>0.10) among the treatments and that have the highest (P=0.03) consumption of digestible organic matter in the control treatment. The animals with diet control in the 24h period select more (P=0.004) against 19 mm of treatment with co-products, while no sieve of the state of the 8 mm pen or the rejection index was lower than the 19 mm, however still the treatment control (P<0.0001) selects against 8 mm effects and the treatment with co-products does not show selection in this section, being the bottom of the sieve in both tests with selection in favor of the bottom of the sieve. An acetate: propionate ratio was higher (P=0.005) for treatment with by-products evaluated for the control treatment, with ammoniacal nitrogen in the rumen and urea nitrogen in the blood greater (P=0.003 and P<0.0001) for by-product concentrate. The control treatment animals with greater (P=0.01 and P=0.03) meal size and meal duration with smaller (P=0.05) number of meals compared to treatment with co-products. The results demonstrated are the necessary ruminal degradation studies of the mixture of corn by-products with the method of efficient use in the feeding of dairy cattle.