M. Kay

Prediction of intake by cattle from degradation characteristics of roughages

Five different straws consisting of two varieties of winter barley, two varieties of spring barley and one variety of winter wheat were chosen due to differences in degradation characteristics determined by using nylon bags incubated in the rumen of cattle and describing the straw using the equation: p = a + b (1 – e –ct ). To increase variation in degradability, batches of the same straws were also treated with anhydrous ammonia in a sealed oven. The straws were subsequently offered ad libitum to groups of steers given a daily supplement of 1·5 kg concentrate and untreated straws were supplemented with urea. The dry-matter intake (DMI) of the straws varied from 3·4 to 5·7 kg/day, the digestible DMI from 1·4 to 3·5 kg/day and growth rate from 106 to 608 g/day. By using multiple regression of a, b, c from the exponential equations characterizing degradability of the straw, the correlation coefficients with DMI, digestible DMI and growth rate were 0·88, 0·96 and 0·95 respectively.

Intensive beef production. II. Replacement of cereals with ground straw

1. A growth trial was carried out with 21 Friesian steers given diets containing either 0%, 30% or 50% ground straw, and concentrates up to 100%. 2. Steers offered the diet containing 0% straw consumed less dry matter per day than steers on the other two treatments. 3. Rates of live-weight gain were 1·20, 1·04 and 0·87 kg/day for the three treatments respectively, and carcass gains were 690, 550 and 440 g/day. 4. Killing-out percentage dropped and alimentary-tract fill increased as the proportion of straw in the diet increased. 5. The dry-matter digestibility coefficients for the three diets, determined at maximal intake, were 79·1%, 62·3% and 56·6%, respectively.

The effect of different dietary energy concentrations on the voluntary intake and growth of intensively-fed lambs.

In a comparative slaughter trial which covered growth from about 16 kg to 40 kg live weight, five groups of six Romney × Swaledale lambs were offered ad libitum five pelleted diets (A to E) in which rolled barley was gradually replaced by an 80 : 20 mixture of rolled oats : oat husks to the extent that the calculated metabolizable energy (ME) concentration fell from approximately 2–9 (A) to 2·5 (E) Mcal/kg DM. Although daily live-weight gains did not differ significantly between treatments, the daily carcass gain fell from 143 g/day on A to 105 g/day on E (P Dry-matter intakes for the whole experimental period were similar for all five diets, but initially intake was lower for diet E than for A (780 v. 927 g/day) and ultimately it was higher for E (1410 v. 1150 g/day). In a second experiment, involving diets A and E and a third diet of chopped dried grass, the pattern of intake and growth changed with live weight in a similar manner to that described above, except that appetite and growth on dried grass were consistently poorer. Daily variation in intake and rumen pH tended to be greater on the concentrate diets. It is suggested that, amongst other factors, the stage of maturity of an animal may influence the point at which the digestible energy content of the diet restricts dietary intake in preference to physical limitations.

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.

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.

The effect of ammonium acetate on the yield and composition of milk from heifers

1. Two experiments are described in which the effects of ammonium acetate on the yield and composition of the milk from heifers given (1) a fat-depressing diet consisting mainly of cereals or (2) a normal diet of silage and sugar beet pulp for maintenance and rationed concentrates according to yield. 2. In the first experiment acetate increased the content of butterfat in the milk from 2·76 to 3·12. This difference was almost significant (P 3. In the second experiment acetate very slightly depressed the total solids and the butterfat content of the milk. 4. In Experiment 1 there was no significant difference between treatments i n the pH of rumen liquor, or in its concentration of total steam volatile fatty acids, but the proportions of acetic and isobutyric acids were higher on the acetate treatment. 5. In Experiment 2 there were no differences in the relative proportions of the fatty acids although the total steam volatile fatty acid concentration was higher on the acetate treatment.

Intensive beef production. 12. Replacement of concentrates with chopped dried grass.

1. A growth trial was carried out using 24 British Friesian steers given diets containing (1) 100%, (2) 60%, (3) 40% and (4) 0% concentrates and chopped dried grass up to 100%. 2. Daily dry-matter intake was significantly lower for steers on Treatment 1 than for steers on the other three treatments. 3. Rate of live-weight gain declined from 1·18 to 0·88 kg/day and carcass gain from 625 to 430 g/day between steers on Treatments 1 and 4. 4. Killing-out percentage dropped from 55·3% (1) to 51·9% (4) and the 8th-10th rib from steers on Treatments 3 and 4 contained significantly more crude protein and less ether-extractable matter than ribs from steers on Treatments 1 and 2.

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.

A note on the recovery of polyethylene particles from faeces an d rumen contents of steers

Two experiments were conducted with three types of polyethylene particles to establish their retention time in castrated male cattle (steers) offered diets which contained predominantly cereals ad libitum . The particles were (1) ‘Ruff Tabs’, a corrugated particle of dimension 1·27 × 0·63 × 0·95 cm3 and subsequently referred to as RT and (2) and (3) plain plastic rods of 1·27 cm length and 0·32 cm (BP) or 0·63 cm (RBP) diameter. In the first experiment with steers weighing 170 or 260 kg, 1 kg of RT particles were excreted in the faeces at a similar rate by the steers of different weights whereas BP particles passed out in the faeces more slowly in the lighter steer. In the second experiment 30 steers weighing 440 kg were slaughtered at 7, 14, 28 and 42 days after dosing with 1 kg of BP, RT or RBP. The recovery of RT was significantly lower ( P

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.