Digestion in the pre-ruminant animal

Abstract

The fore-stomachs of ruminant animals do not develop fully and assumc their characteristic digestive functions until the young animal begins to eat substantial quantities of solid food. When young calves consume liquid feed nearly all of it by-passes the reticulo-rumen and passes through the omasum into the abomasum as a result of the reflex closure of the oesophageal groove. The subsequent course of events during digestion in the abomasum and small intestinc has for long been regarded as being closely parallel to that in the stomach and intestines of monogastric animals. However, recent more detailed investigations of the processes of digestion have shown that the digestive capabilities and the development of digestive function in pre-ruminant animals differ in several respects from those in other young animals.Efficient digestion and utilization of nutrients require that food pass at a suitable rate through an alimentary tract endowed with appropriate enzymes and absorptive mechanisms that will allow hydrolysis of complex molecules and absorption of the products. T h e passage into the lower gut of undigested or unabsorbed food residues provides a substrate for undesirable bacterial growth and may lead to diarrhoea.The digestive system of all young mammals is well adapted to the digestion of milk, and young pre-ruminant animals use the fat, protein and carbohydrate from milk with the same remarkable efficiency as do the young of other species. However, when nutrients are supplied from sources other than milk, it will be seen that certain digestive abilities of the pre-ruminant animal are found to be more limited, and either not to develop or to develop more slowly than those of other mammals.

Development of milk replacer for rearing kids

“…CP digestibility did not differ significantly between groups. The range of acid detergent fibre (ADF) digestibility was 7 to 20%, which is consistent with the findings of Porter (1969). The digestibility of nutrients depends on the development and capacity of the digestive tract (Roy, 1980;Thivend et al, 1980).…”

Pepsin and Pancreatin Supplementation of Calf Milk Replacer Containing Soy Protein

“…1977). This is understandable in view of the 473 in vitro results obtained in the present study and in previous work (Jenkins et al 1980 (Mylrea 1966;Porter 1969;Chow and Bell 1976 Fries and co-workers (1958) found that the addition of 0.57o pepsin to a milk replacer produced no improvement in growth of preruminant calves. The milk replacer, composed offinely ground corn, corn distillers' solubles, whey, skim milk and soybean flour, atypical by today's standards, was fed as a gruel.…”

“…Les sujets recevant la ration de There have been numerous unsuccessful attempts to substitute vegetable or fish proteins for milk proteins in liquid diets for preruminant calves (Porter 1969; Radostits and Bell 1970;Roy 1970). Many of the experiments were conducted with soybean products, with the cruder products giving the poorest calf performance (Roy 1970).…”

“…Many of the experiments were conducted with soybean products, with the cruder products giving the poorest calf performance (Roy 1970). Typically, the use of soybean flour in milk replacers, as the principal source of protein, has resulted in low rates of weight gain and poor dry matter and protein digestibiliries (Noller et al 1956: Porter 1969Monill et al 1971; Roy er al. 1977) .…”

Susceptibility of Proteins Used in Calf Milk Replacers to Hydrolysis by Various Proteolytic Enzymes

“…(Hill et al 19'70;Roy 1970 Trypsin, chymotrypsin and carboxypeptidase are secreted into the small intestine of the calf via the pancreatic juice (Porter 1969). Each enzyme has good proteolytic activity within a pH range of I -9 (Boyer et al 1960 …”