N. A. MacLeod

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.

Intensive beef production. 4. The effect on nitrogen retention of all-concentrate diets containing different levels of fish-meal.

1. All-concentrate diets given ad libitum and containing different levels of fish meal, and varying in crude protein content from 16 to 22% in dry matter were given to eight Friesian steers at 150 kg. and at 240 kg. live-weight.2. At a mean live-weight of 150 kg., the retention of nitrogen increased significantly to a maximum of 41.5 g. per day on the diet having 22% crude protein in dry matter. At 240 kg. live-weight, the maximum retention of 37 g. per day was achieved at 20% crude protein in dry matter.3. Faecal nitrogen excretion per unit of metabolic body weight was approximately constant at all protein levels and at both live-weights.4. Urinary nitrogen excretion per unit of metabolic body weight increased with increasing crude protein level in the diet and for any crude protein level was higher at 240 kg. than at 150 kg. live-weight.

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.

Nutrition of the early-weaned calf. IX. Nitrogen retention from different protein sources in calves fed ad libitum

1. Nitrogen balance studies were conducted on 8 early-weaned calves fed on four diets containing respectively Peruvian fish meal, soya bean meal, groundnut meal and dried distillers grains as the major sources of protein. 2. Nitrogen retention differed significantly between diets, being highest on the fish meal diet, and lowest on the groundnut diet.

Intensive beef production. 5. The effect of different sources of protein on nitrogen retention.

1. Nitrogen balance studies were made on 8 Friesian steers given allconcentrate diets containing fish meal, soya bean meal, groundnut meal or cottonseed meal. 2. There were no differences in nitrogen retention but voluntary feed intake was significantly lower on the fish meal diet. 3. Adjustment of nitrogen retention to constant dry matter intake resulted in significantly higher values for the diets containing fish meal and cottonseed meal than for the others. 4. Rumen p H, rumen ammonia and blood urea were all much lower on the fish meal diet.

Urea and cereals as supplements for ruminants offered barley straw

In three trials, two with suckler cows and one with lambs, supplementary forms of dietary nitrogen and/or energy were added to a basal diet of barley straw offered ad libitum . The nitrogenous supplements appeared to have a small effect on the intake of straw but only when they were available for frequent consumption. The addition of cereals to the diet did not affect the intake or digestibility of the straw but reduced the live-weight losses.

Nutrition of the early-weaned calf. XI. Intake of diets differing in energy concentration

1. A growth and digestibility trial was carried out with 27 British Friesian calves given diets having either 3·1, 2·8 or 2·4 Meal metabolizable energy per kg dry matter and either the same concentration of protein or the same protein-to-energy ratio. 2. Daily dry-matter intake and rate of gain in live weight increased significantly as the energy concentration of the diet was reduced. There were no significant differences in digestible-energy intake between calves given the different diets, although the trend was the same as for dry-matter intake. 3. Both dry-matter digestibility and energy digestibility were lowest for the low-energy diet.

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.

Intensive beef production. 6. A note on the nutritive value of high moisture barley stored anaerobically.

T he use of barley for intensive beef production, as described by Preston, Aitken, Whitelaw, Macdearmid, MacLeod and Philip (1963) is now a well established practice, but one of the hazards of this feeding system is bloat. There is evidence that the risk of this condition is accentuated if the barley husk is broken down too finely as happens if the grain is ground (Preston, Macdearmid and MacLeod, 1963; Preston, 1964). It was therefore recommended that barley should be processed in a roller mill and that the moisture content should be at least 16% (Preston, 1963), for if the grain is drier than this it is difficult to prevent excessive shattering and destruction of the husk. Suitable containers, which can be sealed in order to ensure anaerobic conditions and so overcome the problem of storing damp grain (greater than 16% moisture) have additional advantages at harvest since they can be filled quickly and easily. The purpose of this experiment was to evaluate the nutritive value of barley stored under these conditions.

Nutrition of the early-weaned calf. XII. The effect of diets differing in physical form on feed intake and rate of gain

1. Intake and digestibility were determined in a trial with 30 British Friesian calves given diets containing straw and either 3·2 (H), 2·9 (M) or 2·6 (L) Meal metabolizable energy per kg dry matter. For one series of diets the straw was chopped and the diets were made into cobs (1·0 × 2·5 × 4·0 cm); for a second series the straw was milled and the diets were made into pellets (1·0 × 1·25 cm) 2. Calves given the H diets containing either chopped or ground straw ate and gained less well than calves given M and L diets but there were no differences in feed intake or growth between calves given M and L diets. 3. The retention of feed residues was greater and the flow of fluid out of the rumen was less for cattle offered the H diet than the L diet.