The Nutrition of the Young Ayrshire Calf

Abstract

The energy and nitrogen metabolism of calves, when given whole-milk diets, has been the subject of experiment for over 70 years. Soxhlet's (1878) work involved simultaneous study of mineral, N and energy balances and these experiments, together with those of Fingerling (1908), Blackwood, Morris & Wright (1936) and of Tomme & Taranenko (1939), appear to be the only ones that have not been complicated by the inclusion of roughage in the diet of the animals. No metabolism studies appear to have been made in which variation in nutritional plane has been employed. Several practical trials have, however, been carried out in which different quantities of whole milk have been given (Filmer, 1948(Filmer, , 1949 and in which higher planes of nutrition have been associated with greater growth, at least during the first 5 weeks of life.In a previous paper (Blaxter & Wood, 1951 c) it was suggested that biological values of proteins, giving their true significance, could be determined by regression analysis of the results of nitrogen-balance experiments in which different quantities of the same diet had been given. The object of the present experiment was to repeat this type of determination using cow's whole milk. In view of the paucity of information on the calcium and phosphorus metabolism and the energy exchange of the young calf in relation to nutritional plane, additional observations on these aspects were made. EXPERIMENTAL Calves and their managementTwo bull calves, which had previously been given colostrum and whole milk, were used. They were housed in metabolism crates; urine and faeces collections were made as previously described (Blaxter & Wood, 1 9 5 1~) .The calves were 5 days old at the commencement of the experiment. Whole milk was given to each calf as its sole diet for three 12-day periods; calf no. 1 3 received 2.6, 5.0 and 5-8 1. in consecutive periods and calf no. 14 received 4.2, 3.4 and 6.6 1. These quantities are step-wise changes of 0.8 1. and were chosen to cover a range of feeding from about maintenance level to two and a half times maintenance. The diets were allocated in such a way that each calf was given widely differing quantities. Two days were allowed between each change-over to allow an equilibrium to be attained. The whole milk used contained I952on the average 3-0-3-1 yo fat and was supplemented by a daily dose of 5 ml. of a mineral mixture containing those trace elements that are required by the rat when milk is the sole diet. Magnesium was also included in this mixture to prevent the hypomagnesaemic tetany of calves that results when whole-milk diets are given (Duncan, Huffman & Robinson, 1935). The composition of this mixture in g/l.was: MgS04.4H,0 0.5, CuS04.5H20 0.5, CoS0,.7Hz0 0.1, F%(S04),.7H,0 20.0, MgC1,. 6H,O 60.0. Five ml. cod-liver oil were given once a week.Milk samples were taken at each feeding (9 a.m. and 8 p.m.) and were preserved with formaldehyde. Urine and faeces were collected daily. Analytical procedureAll analyses for nitrogenous constituents were made at 2-day int...

Utilisation of the metabolisable energy of ewe's milk by the lamb

“…In this experiment the mean digestible energy coefficient for ewe's milk was 98.4%, and, as in the milk feeding experiments of Blaxter and Wood (1952) with calves, the plane of nutrition had no effect on the coefficient. Blaxter (1952) and Gonzalez-Jiminez and Blaxter (1962) showed that cow's milk fed to calves has a metabolisable energy coefficient of 95%; and Walker and Jagusch (1969) obtained a value of 94.3% with lambs.…”

Methods of Assessing the Energy Values of Foods for Ruminant Animals

“…In the Mockern experiments (see p. 132) it was usual to add about 2 kg of the trial feed to 6-8 kg of basal ration. So, if errors of the same magnitude as we find had applied, each net-energy determination would vary by +zo-30 Cal./ (Blaxter & Wood, 1952).…”