Effects of Rumen-Undegradable Protein on Dairy Cow Performance: A 12-Year Literature Review

Abstract

In order to integrate and analyze knowledge on the use of protein supplements and protein nutrition of lactating dairy cows, we compiled a review of 108 studies published throughout the world, but principally in the Journal of Dairy Science between 1985 and 1997. In 29 comparisons from 15 metabolism trials, soybean meal was replaced by high amounts of rumen undegradable protein (RUP) as a supplement; the benefits were not consistently observed for flow to the duodenum, essential amino acids, or lysine and methionine. High RUP diets resulted in decreased microbial protein synthesis in 76% of the comparisons. However, fish meal provided a good balance of lysine and methionine when calculated as a percentage of total essential amino acids. In 127 comparisons from 88 lactation trials that were published from 1985 to 1997, researchers studied the effects of replacing soybean meal with high RUP sources, such as heated and chemically treated soybean meal, corn gluten meal, distillers grains, brewers grains, blood meal, meat and bone meal, feather meal, or blends of these sources; milk yield was significantly higher in only 17% of the comparisons. Fish meal and treated soybean meal accounted for most of the positive effects on milk yield from RUP; corn gluten meal resulted in mostly negative results. The percentage of fat in milk was depressed more by fish meal than by other RUP sources. Protein percentage was decreased in 28 comparisons and increased in only 6 comparisons, probably reflecting the decrease in microbial protein synthesis, as was observed for diets high in RUP. The data strongly suggest that increased RUP per se in dairy cow diets, which often results in a decrease in RDP and a change in absorbed AA profiles, does not consistently improve lactational performance.

Efeito da sobrealimentação com fontes de proteína de diferentes degradabilidades sobre a ovulação em ovelhas Santa Inês

“…No entanto, o glúten de milho na quantidade utilizada neste experimento não reduziu o consumo de MS. A proporção desse ingrediente na dieta (7,45% da MS) foi próxima ao nível máximo consumido por cordeiras Santa Inês (7,91%) em experimento conduzido por Salvador (2007). Santos et al (1998), ao analisar três artigos (Holter et al, 1992;Polan et al, 1991;Wohlt et al, 1991), em que o farelo de soja foi totalmente substituído pelo glúten de milho em dietas à base de silagem de milho para vacas leiteiras, observaram menor ingestão de MS. Em nenhum dos trabalhos analisados a causa da redução na ingestão de MS foi relatada. No entanto, a redução no consumo pode ter como causa a baixa palatabilidade do glúten de milho (Teixeira, 1997).…”

The partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea and its effect on the performance, metabolism and digestibility in dairy cows

“…10 to 20 g/kg DM) are associated with a reduction in DM intake and performance (e.g. Brito and Broderick, 2007;Santos et al, 1998), which may be related to a reduction in digestible, undegradable protein supply (DUP). In this study the predicted reduction in DUP supply of the urea-containing diets was comparatively low at 7 g/kg DM.…”

Desempenho, composição do leite e metabólitos sanguíneos de vacas Holandês x Gir manejadas em pastagem de Brachiaria brizantha cv. Marandu e suplementadas com grão de soja tostado

“…A soja processada termicamente constitui-se na melhor fonte vegetal de proteína não degradável no rúmen (PNDR), pois foi a que mais aproximou do perfil de aminoácidos da proteína microbiana, apesar de sua deficiência em metionina (Santos et al, 1998).…”