F. G. Whitelaw

The nutrition of the early-weaned calf. II. A comparison of commercial groundnut meal, heat-treated groundnut meal and fish meal as the major protein source in the diet

IN a previous communication (Preston et al, 1960) we reported no difference in nitrogen retention between calves given diets containing either 15% groundnut meal or 10% groundnut meal and 5% white fish meal. In a concurrent feeding trial using similar diets there was no difference in liveweight gain from 3 days to 84 days of age although increase in height at withers and food conversion ratio were significantly better for the diet containing white fish meal. These experiments can be criticised, however, on the ground that (a) the substitution of 5 % white fish meal for groundnut meal altered the quality of only 20 % of the total nitrogen in the diet; and (b) the level of crude protein in the diet was only slightly below that required to promote maximum nitrogen retention when groundnut meal alone was the major protein source in a diet given at a level of 8 % of metabolic body weight (Whitelaw, Preston and Ndumbe, 1961). The fact that the ratio of protein to energy in the control diet was near optimum means that any attempt to increase the nutritive value of the protein by reducing its solubility (Chalmers, Cuthbertson and Synge, 1954), or by improving its biological value, would have only a marginal effect on nitrogen storage since any increase in the amount of nitrogen absorbed as amino acid would be surplus to the animals requirement and would be deaminated and excreted in the urine.

Intensive beef production 3. Performance of Friesian steers given low-fibre diets

Two groups of twelve-week-old Friesian steer calves were self-fed to a slaughter weight of 400 kg. on diets composed solely of either 85% rolled barley or ground maize and 15% of a supplement providing additionalprotein, calcium, phosphorus, iron, copper, cobalt, salt and vitamin A and vitamin D. There were no health problems on the barley diet, but five of the 15 cattle given maize died from bloat. Surviving animals on the maize diet took 344 days to reach a carcass weight of 231 kg.; comparable data for the barley-fed cattle were 362 days and 222 kg. The tenth rib cuts from the carcasses of cattle given maize contained significantly more fat and less water and ash than comparable cuts from the barley animals. Feed conversion ratio on the barley diet was 4·76. A comparison between the Friesian steers in the present trials and others given a lower energy diet containing ground roughage showed that with increasing concentration of the ration there was an increase in rate of gain, killing-out percentage and content of ether extract in the tenth rib cut.

The nutrition of the early-weaned calf. I. The effect on nitrogen retention of diets containing different levels of groundnut meal

1. All-concentrate diets containing four different levels of Peruvian (anchovy) fish meal and varying in crude protein content from 14·8% to 21·7% in dry matter were given ad libitum to 8 early-weaned Friesian calves over a live-weight range of 60–100 kg. 2. Nitrogen retention was significantly higher on diets containing 21·7% and 19·4% crude protein in dry matter than on diets with 16·8% and 14·8% crude protein. Nitrogen retention as a percentage of dietary intake appeared to be less on the diet with 21·7% crude protein in dry matter than on the other diets. 3. From these data it was calculated that the digestible crude protein requirement for a calf of 82 kg. live-weight gaining at 909 g. daily is between 270 and 340 g.

The nutrition of the early-weaned calf V. The effect of protein quality, antibiotics and level of feeding on growth and feed conversion

1. A 2×2×2 factorial experiment was carried out with 8 blocks of 8 early-weaned Friesian male calves on the 8 treatment combinations of the following factors: (A) groundnut meal versus white-fish meal as the major protein source; (B) presence versus absence of antibiotic and (C) restricted versus ad lib. feeding. The experiment was conducted over the live-weight range 55–90 kg. 2. The inclusion of fish meal rather than groundnut meal in the diet resulted in highly significant increases in both rate of gain and feed conversion efficiency (P 3. The addition of antibiotic to the diet increased rate of gain (P ad lib. feeding level as a result of antibiotic supplementation. 4. Feed conversion ratio was lower and feed intake and rate of gain were higher on ad lib. than on restricted feed (P 5. There was a significant (P ad lib. feeding was greater in the presence than in the absence of antibiotic. No other significant interactions were observed. 6. The use of fish meal in preference to groundnut meal is shown to be justified on economic grounds.

Intensive beef production. 2. The effect of three, twelve or sixteen week weaning on the performance of Aberdeen-Angus crossbred cattle.

1. Some characteristics are described of 10 steer progeny of a Friesian bull which is known to have carried the factor for muscular hypertrophy. 2. On average these steers had a higher birth weight, lighter hide and liver, smaller feet and cannon bones, a lower percentage of fat and higher percentage of lean in the 10th rib joint, than the progeny of three other Friesian bulls reared at the same time and under the same conditions. 3. No one character was an adequate criterion for separating affected from normal progeny. It appears possible that the bull concerned was homozygous for the double muscling gene, and that all his progeny showed one or more symptoms of the condition.

The nutrition of the early-weaned calf VI. The effect of supplemental lysine and methionine on the utilisation of groundnut protein

1. Nitrogen balance studies have been conducted on eight early-weaned calves receiving four diets containing, respectively, groundnut meal, groundnut+lysine, groundnut+lysine+methionine and white-fish meal as the major protein source. 2. There were no significant differences between groundnut meal diets i n any of the measurements examined. On the fish meal diet all measures of nitrogen retention tended to be higher than the corresponding values for groundnut meals. 3. Daily live-weight gains were significantly higher on the fish meal diet than on any of the groundnut diets (P 4. It is suggested that the supplementary amino acids, being highly soluble, were rapidly deaminated by rumen micro-organisms.