Digestion of milk protein and methanol-grown bacteria protein in the preruminant calf. II. Amino acid composition of ileal digesta and faeces and blood levels of free amino acids

Abstract

Summary. The aim of this trial was to study the balance of the amino acid digestion of milk and of methanol-grown bacteria in the terminal small intestine and the hindgut of the preruminant calf. Two diets (control and bacteria) were used. The protein of the control diet was furnished exclusively by skim-milk powder ; 50.5 p. 100 of the protein of the bacteria diet was supplied by methanol-grown bacteria, and the rest by skim-milk powder and synthetic amino acids.Except for methionine, the apparent digestibility of all the amino acids assayed was lower in the terminal small intestine than in the whole digestive tract but the differences were usually less than for total nitrogen (table 5). The largest difference concerned cystine whose apparent digestibility increased from 76 p. 100 in the terminal ileum to 87 p. 100 in the faeces for the control diet, the corresponding values for the bacteria diet being 64 and 79 p. 100. The diaminopimelic acid of dietary bacteria did not seem to be absorbed in the small intestine but large quantities disappeared in the large intestine (table 7). Amino acid digestibility was higher for the milk than for the dietary bacteria, except for threonine and glycine in the terminal ileum and glycine and alanine in the faeces (table 5).The ileal digesta were richer than the faeces in threonine, serine, proline and cystine and were poorer in methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine and arginine (tables 2 and 3). These differences might result from a larger proportion of endogenous protein and a lower amount of gut bacteria protein in the digesta, which also contained more dietary protein than the faeces, at least with the bacteria diet, as shown by the quantities of diaminopimelic acid found with that diet. The respective proportions of dietary, endogenous and gut microbial proteins estimated in the terminal ileum were 16, 71 and 13 p. 100, respectively, with the control diet.The lower digestibility of nitrogen from methanol-grown bacteria seemed due mostly to bacterial wall protein (especially peptidoglycan) resistance to digestion in the small intestine (table 3). However, the differences as compared to milk protein were small ; they did not permit us to show the unavailability of any particular amino acid (except for diaminopimelic acid) at the digestive or the metabolic level.Introduction.

Digestibility, blood levels of nutrients and skin responses of calves fed soyabean and lupin proteins

“…However, they still compared well with values reported for non-antigenic alcohol-treated (0.89, Guilloteau et al, 1986;0.81 Lall6s ef al, 1994) (Combe et al, 1980;Souffrant, 1991). The lower apparent digestibility of most AA with the soyabean and lupin diets than with the control diet agrees with results obtained by other workers with milk substitute diets containing non-milk protein sources such as bacteria (Guilloteau et al, 1980;Sedgman et al, 1985), fish, soyabean (Guilloteau et al, 1986; Nunes do Prado et al, 1989a, Caugant et al, 1993b), or pea (Bush et al, 1992). …”

Importance of the abomasum in digestion in the preruminant calf

“…Thus, when a calcium-rich diet is given, the apparent digestibility and the percentage of calcium intake which is retained decrease as the calf's age increases (Paruelle, Toullec and Mathieu, 1973) Guilloteau et al,1980a). In our experimental conditions, the nature of the protein had less effect than the gastric emptying rate, but probably this would not be so if the protein substitute used was less digestible than that of the hydrolysed fish ; thus, non-hydrolysed fish protein or that of soya concentrates is less digestible than hydrolysed fish protein Toullec et al,1977), although its gastric emptying rate is slower (Guilloteau et al,1975 (Mercier, Grosclaude and Ribadeau-Dumas, 1971 ;Brignon et al, 1977 (Guilloteau et al, 1980b).…”

Proteins in the digesta of the pig : amino acid composition of endogenous, bacterial and fecal fractions

“…The amino acid compositions of the various samples have been compared two by two by calculating the X Z distance, as already described by Guilloteau et al (1980) and Darcy, Laplace and Duée (1983). A method of correspondance analysis was also used to make an overall comparison of the amino acid composition of the various proteins studied (Guilloteau, Sauvant and Patureau-Mirand, 1983 ;Darcy, Laplace and Duée, 1983 The proportion of bacterial protein in the fecal protein was estimated using DAPA ratios in relation to total nitrogen.…”