Two rearing experiments were carried out to study the effect of omitting three feeds per week from an early-weaning system on the performance of 110 male calves. From the third week the calves in the experimental groups received only one feed of milk substitute on Saturdays, at 11.00 hr; on Sundays they received no milk substitute at all; from Monday to Friday they were fed twice daily. The animals in the control groups received milk substitute twice daily during the 7 days of the week, quantity per feed being the same as for the experimental groups.

The calves were weaned at 8 weeks in experiment 1 and at 5 weeks in experiment 2.

In both experiments the calves in the control group had a significantly higher daily gain than the experimental calves during the third to the fifth weeks. From 6 to 16 weeks arid for the experiment as a whole no significant difference in weight gain or feed intake were observed. The omission of three feeds per week offered considerable advantages in the saving of labour and convenience of management.

Seven research and teaching centres have co-operated in an experiment involving 154 sows. The experiment compared the effect of feeding four different patterns of feed intake during pregnancy upon reproductive performance of sows. In each case approximately 220 kg of feed were given during each gestation according to four patterns of intake designated Constant (C), Low-High (L-H), High-Low (H-L) and High-Low-High (H-L-H). During lactation all animals were given a daily ration of 3·7 kg of feed for litters of five pigs or less, and 0·4 kg for each additional piglet. Wherever possible the sows remained on the same nutritional regimes for three parities.

Although the pattern of feed intake slightly affected the live-weight changes of the sows during the course of pregnancy, the treatments had no significant effects on overall change in weight of the sows in pregnancy or in lactation in any of the three parities. The live weights of the sows at the end of the third parity were very similar for all treatment groups.

The patterns of feed intake had no appreciable or significant effect on the numbers of pigs born, their average weight at birth or upon the numbers of pigs which survived to weaning at 6 weeks or their live weight. The health and breeding regularity of the sows were also unaffected by the treatments.

There were differences between the centres in many of the variables which were compared, but there was no evidence of any important centre × treatment interactions.

It is concluded that, at the levels of intake given in pregnancy and lactation in this experiment, there are no beneficial or detrimental effects of changing the pattern of intake during pregnancy.

1. The primary growth of a sward of S24 perennial ryegrass was harvested between 23 April and 9 May 1968, artificially dried and either chopped or coarsely milled. The two physical forms of grass were wafered either alone or together with 50% by dry weight of rolled, anaerobically stored barley, and given to 7-month-old, Hereford × British Friesian steers in an experiment of 2 × 2 factorial design.

2. A representative group of animals was slaughtered at the beginning of the experiment, and the remainder were individually fed ad libitum for 70 days, after which they also were slaughtered. During the feeding period digestibility was determined by total faecal collection from all the animals individually on two occasions.

3. Dry-matter intake and live-weight gain were similar on all feeds. The weight of gut contents as a percentage of final live weight was significantly lower and the carcass-weight gain was significantly higher for animals given wafers containing barley compared with those for animals given wafers of grass alone.

4. Coarse milling compared with chopping reduced the apparent digestibility of dry matter, organic matter, cellulose and energy; the addition of barley increased the digestibility of organic matter but further reduced that of cellulose.

5. The efficiency of conversion of digested energy to empty-weight or carcass gain was similar for wafers containing the two forms of forage, but the digested energy of wafers containing barley was converted to carcass weight with significantly greater efficiency than that of wafers consisting solely of grass.

6. Physical separation of the tissues of sample joints failed to show any significant differences in the proportion of fat, muscle and bone as a result of either differences in physical form or the inclusion of barley.

7. The results indicate that live-weight gain is an insufficiently sensitive measurement by which to assess the true productive potential of feeds given to ruminants in short-term experiments.

Pigs fed ad libitum were exposed to changes from 22 to 33°C and from 33 to 20°C. Responses were investigated in two groups of animals kept for three successive periods of four weeks at 22°, 33° and finally 20°C.

Twenty-four hr after the first change, from 22 to 33°C, there was a decline in body weight; after the second change, from 33 to 20°C, there was a large increase. After the change to 33°C, feed intake by the second day and growth rate for the first week were about the same as at the end of the four weeks, but about 12 days were required for water intake, rectal temperature and respiratory rate to reach steady values.

After the change from 33 to 20°C, steady values for respiratory rate and rectal temperature were reached in one and 12 days respectively. The rate of gain in weight increased to reach a peak nine days following the temperature change and then declined.

Three experiments were carried out in which the level of feed intake of pigs growing from approximately 30 to 90 kg was alternately raised and lowered, using different amplitudes and time-periods. Within each experiment, the total feed intake and the length of the experimental period were the same for all treatment-groups.

The two amplitudes which were examined were 112%–88% and 125 %–75% of standard scales of feeding. The time-periods between switches to the alternate level were 1, 3, 7 or 14 days. The impact of the fluctuations in feed intake on overall performance and carcass composition was either trivial or small, and in no case exceeded 5% for any one measurement. It is concluded that fluctuations in feed intake occurring in practical situations will have only trivial effects on performance, provided that pigs receive similar amounts of feed in the same overall period of time.

1. Young cattle were fed on four types of wafer containing chopped or coarsely-milled dried grass, with or without 50% of barley.

2. At slaughter, the alimentary tract of each animal was removed and the contents of each part were weighed and sampled to determine the extent and site of digestion. Chromic oxide was used as an indigestible marker.

3. The form in which the grass was processed had no effect on any of the parameters measured.

4. The dry-matter content of the digesta in all parts of the alimentary tract was significantly higher when barley was included in the wafers. The inclusion of barley decreased the proportion of acetic acid and increased the proportion of butyric acid in the rumen liquor. The proportions of propionic and valeric acids were unaffected. Barley also appeared to reduce the proportion of digestible dry matter which disappeared in the forestomachs (31·44%) compared with that when grass was given alone (42·59%).

5. With grass alone about 70% of the apparently digestible cellulose disappeared from the forestomachs, but the technique used did not allow a good estimation of these proportions when mixed diets were given. The retention time of dry matter in the forestomachs was not affected by the diet but the inclusion of barley in the wafers increased the retention time of cellulose in the forestomachs.

6. Of 1·6·1·9 kg of starch ingested in mixed diets, 92-96% was apparently digested in the forestomachs, and only 80-130 g per day escaped rumen fermentation. The intake of starch on diets of grass alone was negligible and almost all the soluble sugars were digested in the forestomachs.

7. More N was recovered at the omasum than was ingested, but the different diets had no effect on the site of digestion of N.

The feeding value of moist barley (approximately 27% moisture) which had been treated with 1·3 % of a mixture of formic (70 %) and propionic (30 %) acids was compared with that of dried barley for growing pigs from 23 to 85 kg live weight. Two experiments were undertaken; 96 pigs were fed ad libitum on one of three diets containing dried or acid-treated moist barley and another 48 pigs were individually fed on one of four diets containing dried or acid-treated moist barley in controlled amounts. These amounts were governed by an allowance of dry matter at a certain live weight.

In neither experiment were significant differences found between the treatments in growth rate or efficiency of utilization of food dry matter. Pigs fed ad libitum showed no significant difference in intake of dry matter, but those given the diet containing dried barley had a higher content of fat in their carcass than those on the acid-treated barley. A total of 21 pigs, 16 fed ad libitum and all receiving diets containing acid-treated barley had a discolouration of fat in the carcass.

1. Measurements of oxygen consumption and rectal temperature were made on young female calves at air temperatures of 9° and 20°C, before and after 4·5 kg milk was drunk at 23° and 39°C.

2. When cool milk (23°C) was drunk at an air temperature of 9°C, vigorous shivering occurred, and during the 2-hr period after feeding, oxygen consumption was significantly higher than in the three other treatments.

3. In all other treatments oxygen consumption increased considerably during the 30-min period which included drinking activity; the average increment, when no thermo-regulatory shivering occurred, was 1·9 ml O2 min−1kg−1.

4. It was estimated that the 58 kcal ‘heat of warming’ required by milk at 23°C drunk at an air temperature of 9°C could be accounted for by the increment in heat production during the 2 hr after feeding and the fall in rectal temperature of 0-2-0-3°C which persisted after feeding in this treatment. These calculations suggested that the effect of a cool liquid on the energy balance of an animal would be less than that predicted from the ‘heat of warming’ required by the cool liquid.

Ewes of seven breeds (Oxford Down, Border Leicester, Finnish Landrace, Southdown, Welsh Mountain, Tasmanian Merino and Soay) were treated with progestagen-treated sponges to synchronize oestrus for an egg-transfer experiment. Ewes of five of the breeds were treated with superovulating doses of pregnant mare serum gonadotropin (PMSG). Mean body weight ranged from 89 kg for Oxford Downs to 20 kg for Soays. Interval from sponge withdrawal to oestrus differed significantly between breeds, ranging from 1·83 days in Finnish Landrace to 3·00 days for Soays, but was not consistently related to ewe weight. Treatment with PMSG prior to sponge removal reduced the interval to oestrus; fertilization rate at the first synchronized oestrus was low. There were marked differences among breeds in proportion of ewes showing oestrus following PMSG treatment, total follicular response, and proportion of follicles ovulated. Ewes of the Finnish Landrace breed, with the highest natural fertility, were equal or superior to the other breeds in every component of response, and yielded more than double the number of fertilized eggs per ewe of the next best breed. Finnish Landrace females 6 to 9 months old made very satisfactory donors. Natural ovulation rates of adult recipient ewes were as follows: Welsh Mountain (23 ewes)—1·43; Border Leicester (15 ewes)—2·00; Finnish Landrace (26 ewes)—3·31.

Seventy Duroc × Landrace weanling pigs (initial weight 20 kg) were used in a 91-day experiment in a semi-tropical environment, to determine the effects of deletion of the vitamin-antibiotic or mineral supplement to a corn-sucrose-soya bean meal diet on performance of pigs in Coastal Bermuda grass pasture lots. Pigs fed the complete diet in confinement in concrete-floor pens had significantly faster body-weight gain than pigs fed the same diet on pasture. Pigs fed the complete diet on pasture gained weight significantly faster than those given the same diet but without a vitamin-antibiotic premix. Those fed the complete diet without a Ca-P-trace mineral supplement on pasture gained weight significantly more slowly than all other groups, and showed lameness and femur and rib fractures (2 animals) indicative of Ca deficiency rickets.

Four levels of a proprietary concentrate (0, 100, 200 and 400 g/day) were offered to Welsh Mountain ewe lambs receiving hay or straw ad libitum for 14 weeks. The apparent digestibility of the energy and nitrogen in the various diets was determined in a concurrent digestibility trial.

The voluntary intakes of the straw and hay dry matter when given alone were 242 and 451 g/day respectively (28·4 and 49·2 g/kg W0·73 per day). Straw intake increased with an increase in concentrate feeding up to a level of 25% concentrate in the total dry matter and then declined. Hay intake declined linearly with increasing concentrate level (3 g/day decline per unit increase in the percentage of concentrate). In each case the total intake of dry matter and digestible energy increased with an increase in concentrate level.

There was a positive within-treatment relationship between initial live weight and voluntary intake, an additional 0·019 Meal ME/day being consumed per kg increase in live weight. Within treatment groups lambs consuming relatively more food also made relatively higher weight gains. Estimates based on published standards of the metabolizable energy intakes required to produce the live weight changes observed on each treatment were considerably higher than the intakes recorded in the trial.

Two experiments were conducted to study the effect of type of cereal and time of weaning on the performance and voluntary intake of lambs.

In the first experiment 20 early-weaned entire male lambs were given diets ad libitum during the fattening period from 15 to 40 kg live weight. The diets were based on either kibbled maize or rolled barley. A high feed efficiency and growth rate were achieved with both diets and differences between them were not statistically significant. The growth rates were 428 and 430 g/day. The cold carcass weights at 40 kg live weight were 19·0 and 19·9 kg and the conversion ratios of dry matter to live-weight gain were 2·33 and 2·22 for the rolled barley and kibbled maize diets respectively.

In the second experiment a comparison was made of the performance of 36 sets of twin lambs, one of each set being weaned at either 6, 13 or 20 weeks of age and the other being left to suck the ewe outdoors. The lambs weaned at 6 weeks had better conversions of dry matter to live-weight gain than lambs weaned at 13 and 20 weeks. The respective conversions of dry matter to live-weight gain were 3·36, 5·64 and 5·52. The lambs weaned at either 13 or 20 weeks had a greater weight at weaning, a greater growth check at weaning and a lower rate of feed intake.

Three levels of soya bean meal (0%, 25% and 50% of the intake of hay dry matter) combined with three levels of pelleted barley (0%, 50% and 100% of the intake of hay dry matter) in a factorial arrangement of treatments were offered to Welsh Mountain ewe lambs receiving hay ad libitum for 14 weeks.

When barley was not given, soya bean meal added at 25% of the hay intake increased hay voluntary intake from 287 g/day to 412 g/day but hay intake was depressed to 339 g/day by a further increase in the level of soya bean meal. When barley was given, soya bean meal did not affect hay intake. With one exception, an increase in barley reduced hay intake, with the result that there were no differences between treatments in the digestible energy intakes of lambs receiving barley at each level of soya bean meal. In general, it was found that an increase in the concentrate allowance (barley + soya bean) reduced hay intake, whereas an increase in the crude protein content of the concentrate increased hay intake. The relationship between live-weight change, metabolizable energy intake and live weight was examined by regression analysis. Although live weight and voluntary intake were unrelated at the start of the experiment, a positive relationship emerged as the experiment progressed.

Finn-Dorset females were allowed to mate on four occasions during a period of 2 years. Those over 2 years old at the start of the experiment carried an average of three pregnancies giving birth to an average of 5·8 lambs per ewe. The proportion of ewes lambing was reduced from 93 to 32% by the occurrence of lambing 6 months previously, but litter size was unaffected either by this or by lactation at the time of mating. The mean live weight of male lambs reared as twins was 23·5 kg at 12 weeks, and 36·7 kg at slaughter (mean age 19·7 weeks, killing-out percentage 46·4%).

1. Rates of heat loss from 12 groups of pigs were measured over 4-week periods in a large direct calorimeter equipped as a pig pen.

2. The levels of feeding in different groups were 34, 39, 45 and 52g/kg body weight per day, and the calorimeter temperatures were 7°, 12°, 20° and 30°C.

3. At 12°, 20° and 30°C the rates of heat loss were related to the level of feeding.

4. At 7°C the mean rate of heat loss was higher than at the other temperatures, and was not related to the level of feeding.

1. Dorset Horn ewes were fed individually to make high (H) and low (L) gains in weight in the last 6 weeks of pregnancy. The gains were 20% (H) and 10% (L) of the live weight in week 14 of pregnancy for ewes with twin foetuses, and 16% (H) and 6% (L) for ewes with a single foetus. Three levels of intake imposed during lactation were denned as low (L) 15·0, medium (M) 22·5, and high (H) 30·0 g of feed dry matter/kg of ewe live weight in week 14 of pregnancy. The lambs were removed 12 to 16 hours after parturition and the ewes were machine-milked twice daily for the first 6 weeks of lactation.

2. Ewes making low gains in pregnancy produced lambs with slightly lower birth weights but the difference was not significant for either twins or singles. Pregnancy treatment had no effect on milk yield or live-weight change in lactation, but fat content was increased in milk from ewes on the H treatment in pregnancy (8·06% v. 7·46%).

3. Level of feeding during lactation did not significantly affect milk yields. The total yields in the first 6 weeks of lactation were (L) 49·4 kg, (M) 60·8 kg and (H) 62·7 kg. However, there were significant effects on milk composition. The treatment means for fat content were (L) 8·34%, (M) 8·05% and (H) 6·84% and for solids-not-fat content were (L) 10·04%, (M) 10·37% and (H) 10·82%.

4. Live-weight losses in lactation were (L) 9·1 kg, (M) 6·3 kg and (H) 3·2 kg.

1. The total rate of heat loss from individual pigs (20 to 40 kg body weight) was measured over 6-hr periods in a small heat sink calorimeter at 7°, 20° and 30°C, with feeding levels of 34, 39, 45 and 52 g/kg body weight per day.

2. Total heat loss at 7°C was significantly greater than at 20° or 30°C; there was no significant difference in heat loss between temperatures of 20° and 30°C.

3. Heat loss per m2 of body surface was independent of feeding level at 7°C. At 20°C, heat loss on the high feeding level was significantly greater than that on the low level, and at 30°C heat loss on both the low and medium feeding levels was significantly greater than that on the very low level.

In-lamb ewes were given 38, 58 and 82 g of digestible crude protein daily at a constant energy intake of 1600 kcal ME per head daily during the last 6 weeks of gestation. There were no significant differences between treatments in live-weight gain of the ewes, lamb birth weight or ewe net body-weight change (the difference between live-weight gain over the experimental period and live-weight loss at lambing).

Digestibility coefficients for the diet components and nitrogen balances were determined on three ewes per treatment during weeks 15-16 and 19·20 of gestation. No differences in the apparent digestibility of the diet components were observed between the two periods. The apparent digestibility of crude protein increased significantly (P > 0·001) with increase in crude protein intake. A significant linear relationship (P<0·01) was found between digestible crude protein intake and nitrogen retention; daily N retention increased by 0·19 g per kg W0·73 for every 1 g per kg W0·73 of apparent digested nitrogen intake per day.

The distribution of chemical fat throughout the major depots of the fleece-free empty body was studied in 30 mature Scottish Blackface ewes from two sources and covering a wide range of fatness.

Relationships between amounts of chemical fat in individual depots and total body fat are presented. These provide information regarding rates of change in the distribution of fat with changing fatness. Information is also presented which allows estimates of the distribution of chemical fat throughout the body to be made from subjectively assessed condition scores.

The effects of freeze-branding young beef animals using two coolants were investigated and an attempt was made to avoid hide damage.

1. Branding with irons cooled in liquid nitrogen gave good markings but resulted in severe hide damage.

2. CO2-branding caused much less hide damage but gave fewer legible brands.

3. Legible brands with both coolants always resulted in some marking of the hide.

4. Branding on the jaw provided a satisfactory means of identification without loss of hide value.