Effects of an Enzyme Feed Additive on Extent of Digestion and Milk Production of Lactating Dairy Cows

Abstract

A study was conducted using lactating Holstein cows with ruminal and duodenal cannulas in a 4 x 4 Latin square design to investigate fibrolytic enzyme supplementation on site and extent of nutrient digestion. The four diets consisted of 45% concentrate, 10% barley silage, and 45% cubed alfalfa hay (dry matter basis) and differed in enzyme supplementation: 1) control cubes, 2) cubes treated with 1 g of enzyme mixture/kg of cubes, 3) cubes treated with 2 g of enzyme mixture/kg of cubes, and 4) both concentrate and cubes treated with 1 g of enzyme mixture/kg of dry matter. The enzyme supplement contained primarily cellulase and xylanase activities. Digestion of organic matter and neutral detergent fiber in the total tract was higher for cows fed the high dosage of enzyme than for cows fed the control cubes. Ruminal digestibility of crude protein was higher, but that of organic matter and neutral detergent fiber was only numerically higher, for cows fed the high dosage of enzyme compared with that of cows fed the control cubes. Higher ruminal digestibility associated with the high dosage of enzyme resulted in more microbial protein synthesis. Milk production increased for cows fed the high dosage of enzyme compared with cows fed the control cubes and effects of the addition of enzyme on milk composition were minimal. The results demonstrated the benefits of using a fibrolytic enzyme additive to enhance feed digestion and milk production by dairy cows. The response to enzyme supplementation was affected more by amount of enzyme than by whether the enzyme was added to forage or concentrate.

Mode of action of exogenous cell wall degrading enzymes for ruminants

“…Numerous studies have reported increased digestion of DM and fibre measured in situ or in vitro (Nakashima et al 1988;Feng et al 1996;Hristov et al 1996;Yang et al 1999;Colombatto 2000;Colombatto et al 2002) or in vivo (Feng et al 1996;Krause et al 1998;Yang et al 1999;Beauchemin et al 2000;Kung et al 2000). These increases in feed digestion are somewhat unexpected given the exceptionally high starch and fibre digesting capacity of the rumen.…”

“…Various studies have shown that exogenous enzymes enhanced rate of in situ or in vitro digestion measured using short-term incubations (Nakashima et al 1988;Feng et al 1996;Hristov et al 1996;Yang et al 1999;Colombatto 2000;Colombatto et al 2002). However, most studies have not found exogenous enzymes to improve the extent of in situ or in vitro digestion (Nakashima et al 1988;Feng et al 1996;Hristov et al 1996;Iwaasa et al 1999;Yang et al 1999;Colombatto 2000).…”

“…However, most studies have not found exogenous enzymes to improve the extent of in situ or in vitro digestion (Nakashima et al 1988;Feng et al 1996;Hristov et al 1996;Iwaasa et al 1999;Yang et al 1999;Colombatto 2000). These results suggest that enzyme additives only degrade substrates that would be naturally digested by the rumen microflora.…”

Consumo e digestibilidade aparente total em bovinos sob suplementação com enzimas fibrolíticas

“…Os autores verificaram ainda que o efeito da utilização do extrato sobre a digestibilidade dos nutrientes pareceu diminuir na estação em que a qualidade da pastagem foi melhor. Da mesma forma, Yang et al (1999) encontraram aumento da digestibilidade da MO (64,4 para 66,5%) e da FDN (38,8 para 42,4%) de dietas contendo 43% de feno de alfafa com a adição de 1 g de uma mistura enzimática (celulase, xilanase)/kg de MS. Além disso, como verificado neste trabalho, estes autores também não observaram efeito da adição de enzimas sobre a digestibilidade total da PB.…”

“…De acordo com Yang et al (1999), as variações no modo de ação das enzimas podem ser atribuídas às diferenças na composição dos complexos enzimáticos comerciais ou à composição da dieta ou do tipo de alimento utilizado. Além disso, segundo Morgavi et al (2000), a formulação dos complexos enzimáticos comerciais é normalmente padroniTabela 5 -Efeito da interação fontes de volumoso × níveis de enzima sobre a digestibilidade aparente total da EB (DEB) …”