The influence of level of grain intake on protein digestion in the intestine of cattle

Abstract

I . Protein digestion in the gastro-intestinal tract of cattle receiving diets with either low or high content of maize was investigated. Digesta obtained from the duodenum and ileum were separated into three fractions; soluble, microbial and particulate, and the amino acid composition of the three fractions and that of the total digesta were determined. The proportion of particulate material digested in the intestine was less from the high-maize than from the lowmaize diet, but more of the particulate fraction entered the duodenum from the high-maize than from the low-maize diet, so the absolute amount of particulate fraction which was digested was greater for the high-maize diet.2. More protein was digested in the rumen from the low-maize diet (high-roughage) than from the other diet. Total digestion of protein from the low-maize diet was also higher.3. Although more protein from the high-maize than from the low-maize diet reached the duodenum, the protein from the low-maize diet was more digestible in the intestine, so the total amount of dietary protein digested in the intestine was the same for both rations.

Site of Protein Digestion in Steers Fed Sorghum Grain Diets. I. Effect of Level of Feed Intake

“…Similarly, Tamminga (1979) noted an increase in the flow through the duodenum of dairy cows when DM intake was increased from 8.2 to 12.9 kg/d. In contrast to our study, Neudoerffer et al (1971) reported that the percentage of protein disappearing in the small intestine was reduced (69.2 vs 75.4%) with increasing intake of maize. When wether lambs were fed at two levels of DM intake (500 or 1,000 g/d) but equal dietary N (11.2 g/d), Goshtasbpour-Parsi et al (1977) noted a significant increase in the amount of total N reaching the omasum; however, the amount of total N reaching the abomasum Of these wethers was not altered by DM intake (probably due to abomasal secretions).…”

“…Level of N intake can be altered by either varying level of dry matter intake or percentage of N in the diet. Most studies have used the latter approach, but the literature contains contradictory reports on the effect of level of N intake on its digestibility in various segments of the gastrointestinal tract (Hogan and Weston, 1967;Neudoerffer et al, 1971;l~rskov et al, 1971a,b; 1 Arizona Agr. Exp.…”

“…There are few published reports on the effect of level of feed intake on protein digestibility within various parts of the gastrointestinal tract. This is particularly true for high grain diets (Nicholson and Sutton, 1969;Neudoerffer et al, 1971;Goshtasbpour-Parsi et al, 1977;Zinn and Owens, 1983). This study was undertaken to determine the effect of two levels of feed intake (95 vs 75% of ad libitum intake) on the site and extent of feed protein digestion and extent of microbial protein synthesis and its degradation in abomasally cannulated steers fed an 81.5% steam-processed, flaked sorghum grain diet.…”

Quantitative microbial protein synthesis in the bovine rumen

“…On a percentage of total N basis, this estimate is slightly less than the 1 gN/day value used by Hogan and Weston (1967) with sheep. It was, however, thought to be more realistic after evaluating data in subsequent experiments and also the data of Neudoerffer et al (1971). Micro scopic examination of rumen contents revealed that protozoa were either absent or present in very low numbers, so microbial estimations were made on the basis of bacteria data.…”

Quantitative microbial protein synthesis in the bovine rumen

“…It was, however, thought to be more realistic after evaluating data in subsequent experiments and also the data of Neudoerffer et al (1971). Micro scopic examination of rumen contents revealed that protozoa were either absent or present in very low numbers, so microbial estimations were made on the basis of bacteria data.…”