Response of Lactating Dairy Cows to Steam-Flaked Sorghum, Steam-Flaked Corn, or Steam-Rolled Corn and Protein Sources of Differing Degradability

Abstract

Protein sources with different degradabilities were fed to 48 lactating Holstein cows receiving 37 or 39% of dietary dry matter as steam-flaked sorghum (360 g/L), steam-flaked corn (360 g/L), or steam-rolled corn (490 g/L) in a 3 x 2 factorial arrangement of treatments. Cows were fed an alfalfa-based diet with 7% soybean meal or 5% of an animal-marine protein blend and 37 or 39% grain. Although not significant, cows fed flaked grain yielded a mean of 1.5 kg/d more milk than did those fed rolled grain. Gross feed efficiency was not affected by grain processing or protein source, but diets with the animal-marine protein blend had 9% higher estimated net energy for lactation than did diets with soybean meal. The greater gains in body weight and increased digestibility of the diets with the animal-marine protein blend verify the higher energy concentration of those diets. Yield of milk protein was increased by flaked grain or the animal-marine protein blend, and flaked grain increased percentages of lactose and solids nonfat. Increasing the ratio of rumen-degradable starch to rumen-degradable protein increased milk protein content and yield linearly and increased contents of lactose and solids nonfat. A linear response of dry matter, organic matter, crude protein, and starch digestibilities was observed as the ratio of rumen-degradable starch to rumen-degradable protein increased. These data show improved performance of dairy cows fed a high rumen-undegradable protein source with diets high in rumen-degradable starch from steam-processed grains.

Effect of Different Rumen Undegraded Protein Level on Feed Consumption, Nutrient Digestion, Body Weight and Body Condition Score in Early Lactating Dairy Cattle

“…These findings show that glucogenic nutrients such as RUP supplements in the study, lead to improve BCS due to decreased body tissue mobilization by increasing DMI. The replacement of RDP with RUP supplements in lactating cows, improved energy balance and led to 9% increases in amount of NEl consuming (Santos et al, 1999).…”

Fontes protéicas e energéticas com diferentes degradabilidades ruminais para vacas em lactação

“…Entretanto, revisões sobre o assunto, publicadas no final da década de 1990 (Huntington, 1997;Santos et al, 1998;Theurer et al, 1999), indicam que a teoria da nutrição "bypass" apresenta inúmeros pontos falhos.…”

“…Segundo Santos et al (1998), o uso de proteína resistente à degradação ruminal se justifica após a máxima exploração da síntese microbiana no rúmen, com o uso de fontes de PNDR de boa qualidade, capazes de complementar a proteína microbiana em Acta Sci. Anim.…”

“…Segundo , o aumento no teor e produção de proteína do leite com fontes de amido de alta degradabilidade ruminal se devem a um fator ou a uma combinação de fatores, dentre os quais podem ser citadas a maior disponibilidade de energia, maior liberação de insulina, devido à maior produção de propionato ruminal, e a um maior fluxo de proteína microbiana para o duodeno. Santos et al (1998), revisaram 21 comparações entre farelo de soja convencional e farelo tratado física ou quimicamente para elevar o teor de PNDR. As fontes ricas em PNDR reduziram o teor de proteína do leite em 8 e não afetaram nas 13 demais comparações.…”

“…A suplementação com uma fonte rica em PNDR não afetou (p > 0,05) o teor nem a produção de gordura do leite. Santos et al (1999) (Yang et al, 2000).…”