Net nutrient flux by visceral tissues of beef steers given abomasal and ruminal infusions of casein and starch.

Abstract

The objective of this study was to quantify changes of net nutrient metabolism by portal-drained viscera (PDV) and liver of four beef steers (253 +/- 7 kg) in response to combinations of ruminal (R) or abomasal (A) infusions of cornstarch (S) and casein (C). The four treatments in a Latin square design were SACA, SACR, SRCA, and SRCR. Steers were fed alfalfa hay (DMI = 4 kg/d) as a basal diet in 12 equal meals delivered every 2 h and they received continuous infusion of S (800 g/d) and C (200 g/d) in 11-d periods. Digestibilities of DM, N, NDF, and starch, ruminal outflow of liquids and DM, and energy and N retention were less (P < .05) for SA than for SR. Net ammonia and glucose release from PDV were greater (P < .01) for SA than for SR. Net total VFA, acetate, and beta-hydroxybutyrate release from PDV and total splanchnic acetate and beta-hydroxybutyrate release were greater (P < .05) for SR than for SA, but starch infusion site had no effect (P > .10) on net urea N transfer or alpha-amino N release by PDV. Net release of ammonia N, propionate, and total VFA by PDV and uptake of urea N by PDV were greater for CR than for CA, but net alpha-amino N release by PDV and total splanchnic tissues were greater for CA than for CR (P < .05). Summation of energy supply by PDV indicated no difference in total supply among the treatments, but relative contribution of energy sources was affected by infusion site. Energy release by PDV per unit of DE intake was .68 and .66 for SA and SR, respectively. Net release of glucose by PDV was greater for SACA than for SACR (P < .05). These results suggest that site of digestion of starch and casein varies the relative contribution of nutrients to energy supply by visceral tissues and therefore varies N use in beef steers.

Effects of forage intake level on nitrogen net flux by portal-drained viscera of mature sheep with abomasal infusion of an amino acid mixture

“…The extent of AA removal by the splanchnic tissues has been shown to vary with level of feed intake (Savary-Auzeloux et al, 2003). The increased NPA of AA observed with increasing DMI in this study is consistent with previous reports in cattle (Huntington et al, 1988;Lapierre et al, 2000) and sheep (Noziè re et al, 2000;Hoskin et al, 2001) and may reflect increased intestinal absorption of AA as a result of increased duodenal flow of dietary, microbial and endogenous AA because of increased available energy (Guerino et al, 1991;Taniguchi et al, 1995). Clark et al (1992) showed that faster rate of passage of feed residues and the microbes out of the rumen at higher intakes resulted in a higher duodenal flow of dietary protein and non-ammonia nitrogen and an increase in microbial protein synthesis.…”

“…One explanation for higher PDV recovery in this study may be partially attributed to a decrease in the absorptive PDV use of AA because of increased available energy substrates. Several reports have demonstrated that greater flow of post-ruminal AA increases the small intestinal OM and starch digestibility (Richards et al, 2002) and increases portal glucose appearance (Taniguchi et al, 1995), and consequently improve AA absorption from the basal diet probably by sparing gut-tissue AA from breakdown. In addition, it was reported that the additional energy supplied by excess AA can improve the absorption of other limiting AA (Schroeder and Titgemeyer, 2008).…”

Avaliação da silagem de grãos de milho úmido com diferentes volumosos para tourinhos em terminação: desempenho e características de carcaça

“…Em alguns trabalhos, a utilização de fontes de amido de alto escape ruminal favoreceu a deposição de gordura visceral, diminuindo o rendimento de carcaça em bovinos e ovinos de corte (Owens et al, 1986;Taniguchi et al, 1995;Luchiari Filho & Moura, 1998). Possivelmente, a utilização de dietas com alto teor de concentrado ou de ingredientes como a polpa cítrica conferiu vantagens adicionais ao rendimento de carcaça, o que não permitiu a expressão dessa melhora da digestão do amido com a utilização da silagem de grãos de milho úmidos.…”

Factors affecting intestinal starch digestion in ruminants: A review

“…These differences demonstrate the complexity of the regulation of α-amylase and indicate that nutritional influences on enzyme regulation may not be comparable between different species of ruminants. Taniguchi et al (1995) infused casein and starch postruminally in steers and demonstrated that in the presence of casein, the supply of glucose from the portal-drained viscera was increased. This suggested that casein (or protein) may somehow improve intestinal starch disappearance.…”