The voluntary intake of water by 24 groups of 3 to 6 Large White pigs (range of mean body weight: 21 to 73 kg) was measured during a total of 48 periods lasting 3 to 12 weeks each in a large calorimeter equipped as a pig pen. The calorimeter temperature was controlled between 7° and 33°C and the pigs were fed at levels ranging from 42 g feed/kg body weight per day to maximal intake. The mean water: feed ratios were between 2·1 and 2·7 at temperatures between 7° and 22°C, and between 2·8 and 5·0 at 30° and 33°C. The range of mean water consumption extended from 0·092 to 0·184 litre/kg body weight per day.

Forty-eight pigs were used to compare the feeding value of barley which had been stored dry, and then hammer-milled, with that of barley stored moist, either anaerobically or treated with 1·3% propionic acid, and then rolled. The pigs were fed from 30 kg live weight for a period of 11 weeks and during this period all consumed the same allowance of dry matter. The growth rate and feed conversion ratio of the pigs given the rolled moist barley were significantly poorer than those of others given dry milled or acid treated rolled barley. There were no treatment differences in carcass attributes.

Microbiological counts made throughout the experiment showed that there was no significant fungal or bacterial development on the acid treated barley. Similar numbers of bacteria were present on the dry barley as on the moist, but the fungal count for the moist grain was always at least 500 times higher than that of the corresponding dry sample. The dominant organisms were identified.

In a further experiment the apparent digestibility of dry matter and nitrogen of diets containing dry, moist or propionic acid treated barley, processed either by milling or rolling, were determined. The highest values were obtained for dry barley. Acid treated moist barley had lower values than moist barley. The method of processing did not affect the apparent digestibility of the dry matter, but that of the N was significantly lower for the rolled barleys.

From among a group of ewes in which oestrus had been induced following progesterone and PMS treatment and which had been mated in the spring, those lambing in early October were used for this experiment. They were divided into three treatment groups: (1) reared their lambs for 24 hr, (2) reared lambs for 16 days and (3) reared lambs for 75 days.

For the ewes rearing single lambs only in groups 1, 2 and 3, 100% (8 of 8), 93% (13 of 14) and 65% (11 of 17) respectively exhibited oestrus between lambing time in autumn and early winter (P<0·05). The average interval to post-partum oestrus was 29, 37, 50 days for group 1, 2 and 3 respectively. Group 3 exhibited first oestrus later than group 1 (P<0·01). These data show that lactation even during the peak of sexual activity has some suppressing effect on both the percentage of ewes showing oestrus and on delaying the onset of oestrus exhibition.

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.

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.

1. An experiment was conducted with dairy cows over two grazing seasons to investigate the feasibility of fixed rotational grazing. Each year a comparison was made between treatment A, which consisted of four equal paddocks grazed for 1 week and rested for 3, and treatment B, which contained five paddocks grazed for 1 week and rested for 4. The influence of the length of the rest periods on output per hectare and per cow was measured. Within each paddock approximately one-seventh of the area was allocated daily to each treatment group, there were no back fences and the paddocks were not topped or harrowed. Stocking rates were identical on both treatments at all times at 6·2 cows per ha throughout 1964; 7·1 cows per ha for weeks 1·9 inclusive and 6·2 cows per ha for weeks 10·20 inclusive in 1968. The fertilizer nitrogen applied (282 kg/ha) was equivalent to a daily rate of 2·02 kg/ha. The feed intake of each cow was measured on three occasions during 1967 and four in 1968.

2. Differences between treatments in outputs per ha were small and on average about 13 000 kg milk and 890 cow grazing days were produced per ha during the 20-week experimental period.

3. Differences between treatments A and B in herbage intake, milk production, milk composition and live-weight change were not statistically significant.

4. When 3·6 kg of a supplementary concentrate was given to some cows, positive responses in milk production, milk composition and live-weight change were found, but the value of the extra milk produced was less than the cost of the concentrate.

1. The metabolic rates of 58 individual piglets kept either on a straw or on a concrete floor at ambient temperatures near to 10°, 20° or 30°C have been measured with ages ranging from newborn to 9 days, and body weight from 1·0 to 3·2 kg. The oxygen consumption was measured on each floor material at the chosen ambient temperature thus allowing paired comparisons for each animal.

2. In comparison with the concrete floor, oxygen consumption on straw was reduced by 18% at 10°C, 27% at 20°C and by 12% at 30°C for pigs 2 to 9 days old. The regression coefficients of mean log (oxygen consumption) on log (body weight) were around 0·66 at 10° and 20°C. At 30°C the value was 0·99 ± 0·14. The regression coefficients were not significantly affected by the presence of a straw floor showing that its effect did not vary with body weight. Corresponding values foi piglets below 24 hours of age were 17% at 10°C, 27% at 20°C and 22% at 30°C ambient temperature.

3. Moving a piglet on to a straw floor at 10°C had the same thermal effect as raising the ambient temperature to 18°C. Similar treatment at 30°C was equivalent to raising the ambient temperature to 32°C.

4. Lowering ambient temperature to increase the temperature gradient between the homeothermic body of the piglet and the environment progressively increased heat loss in all cases. There was a concomitant decrease in the calculated conductance between core and environment which was more pronounced for the piglets lying on the concrete floor.

The least squares analysis on birth, weaning, 6-month and yearling weights in Magra lambs showed that years of lambing, age and weight of dam at lambing and sex of lamb significantly affected all the body weights except the age of dam which did not significantly affect 6-month and yearling weights. Adjustment of these weights for significant effect will be necessary in obtaining estimates of genetic and phenotypic parameters.

Dried poultry manure, produced locally by sterilization and drying, was evaluated as an addition to a conventional diet, at levels of 10, 20 and 30%, for growing pigs from 23 to 85 kg live weight. The 32 pigs remained healthy and the dried manure had no apparent adverse effect on the carcasses.

There were significant linear relationships between the amount of manure added to the conventional diet and growth rate, feed conversion efficiency and certain carcass characteristics. For every 10% addition of manure, growth was reduced by 0·02 kg/day, feed conversion efficiency by 0·25 units and killing-out percentage by 0·96. The dried manure contained about 30% crude protein and was a rich source of minerals.

Heritabilities of birth, weaning, 6-month and yearling weights adjusted for significant non-genetic factors and obtained from half-sib correlations were 0·10±0·03, 0·22±0·05, 0·37±0·09 and 0·48±0·07 respectively. Genetic correlations of birth weight with later weights were small and negative except with weaning weight. Genetic correlations among other weights were large and positive. The phenotypic correlations among these weights were positive and statistically highly significant.

Records of milking rate, milk yield and milk composition were collected over 12 yr from 123 Ayrshire heifers in their first lactation in one herd. Three direct measures of milking rate, i.e. peak flow rate, machine rate and overall rate were closely correlated and each was also correlated with total lactation yield of milk. Milking rate accounted for only a very small part of the variation in fat and total solids percentages. The mean yield of milk per milking in early lactation was a better predictor of total lactation yield than was milking rate but, among animals giving the same early lactation yield of milk, the faster milkers gave higher lactation yields than the slower milkers.

A numerical model of male and female replacement processes in a dairy cattle population was constructed in order to describe the long-term genetic and financial consequences of selection amongst bulls in AI.

Changes with time in the relative contribution of different generations of offspring to the total genetic improvement of the population were described. It was shown that the genetic change resulting from a single selection process amongst the males eventually approaches an equilibrium many years after selection is practised. Owing to the delays involved in the progeny test, individual males made no genetic contribution for a period of 10 years and a small but constant contribution thereafter.

The costs of bull testing and selection, and the monetary benefits obtained from it, were estimated. Current selection procedures proved to be highly profitable at prevailing market prices. Capital invested in the testing programme was recovered within 2 to 5 years of the first offspring calving.

The effect of changes in milk prices and feeding costs on monetary returns was examined. It was concluded that sire testing programmes are likely to prove unprofitable only under extremely adverse economic conditions.

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.

Two groups of five lambs were removed from their dams within 48 hr of birth and artificially reared to a slaughter weight of approximately 32 kg on a milk replacer given cold, hay and concentrates. Voluntary intake of the feeds was recorded together with growth rates and carcass composition of the lambs.

The two groups of lambs were slaughtered at 58 or 67 days of age with growth rates of 459 and 433 g/day, respectively. The mean milk replacer dry matter consumed per lamb was 34·9 kg and 39·3 kg and concentrate dry matter intakes were 3·1 kg and 4·1 kg. Intakes of hay were negligible. Food conversion efficiencies were 0·70 and 0·67 kg of live-weight gain per kg of dry matter consumed. The mean carcass weights were 18·1 kg and 19·5 kg with mean muscle, bone and fat contents of 48·7%, 16·2% and 35·1 % for lambs slaughtered at 58 days and 48·0%, 14·7% and 37·2% for those slaughtered at 67 days.

1. Forty Greyface (Border Leicester ♂ × Blackface ♀) and 40 North Country Cheviot ewes, due to lamb to a Suffolk ram in April 1969, were housed during December 1968 in eight groups of 10 ewes, the breeds being penned separately.

2. One pen of each breed received a basal diet of either hay, grass silage or arable silage with a ‘high’ level of concentrate supplementation and one pen of each breed was given hay with a ‘low’ level of concentrate supplementation. Within each pen, five of the 10 ewes were clipped at housing and the other five were clipped in the following June.

3. Voluntary intakes of the basal diets declined with advancing stage of pregnancy, particularly for those receiving grass silage. Feed had no differential effects on the performance of the ewes in terms of wool yield, body-weight change, birth weight of lamb per ewe or perinatal lamb mortality.

4. The Greyfaces clipped at housing yielded less wool than those Greyfaces clipped in the following June. Time of clipping had no influence on the wool yield of the Cheviots. Wool grades were not affected by time of clipping. Ewes clipped in December performed significantly better than ewes not clipped until June with a higher proportion of ewes producing multiple births (P<0·1), a higher total birth weight of lamb per ewe (P<0·01) and a reduced perinatal mortality of the lambs (P<0·05). The total effect of this improved performance was that the clipped ewes produced 53 ·5 % more live lambs than those ewes not clipped until the following June.

Body temperature and respiratory rate were investigated during the hottest months of the year in five docked and five undocked fattailed Awassi rams, together with the effect of month and docking on these physiological variables.

Month had significant effects on both variables in the two groups. Diurnal variation in rectal temperature was significant in both groups.

Docked rams maintained significantly lower rectal temperatures and respiratory rates than their controls.

A variety of energy and protein supplements for winter diets based on barley straw were tested in experiments carried out over three years with spring-calving suckler cows. All the supplements resulted in satisfactory calf weaning weights and cow performance but there were indications that a low level (2·3 kg) of barley plus 68 g urea adversely affected the birth weights of calves and their performance from birth to turnout.

Haemoglobin types of two Indian breeds of sheep were related to ram and ewe fertility and lamb mortality. Rams with Hb B type had a significantly higher number of lambs born to ewes mated to them. Ewe fertility and lamb mortality were better, but not significantly so, in animals with Hb B type.

Forty-eight Suffolk × Clun lambs were used in an experiment to investigate the effects of two times of removal from the dam and two feeding frequencies upon milk intake over the first 4 days on an artificial rearing system.

Lambs removed at birth consumed significantly more milk replacer at feeding periods up to 32 hr after removal than lambs removed at 24 hr after birth. Removal at birth also significantly increased voluntary milk intake between feeding periods for up to 32 hr and from 64 to 80 hr after removal.

Feeding the lambs during a 16-hr period in a 4, 4, 8 hr sequence instead of 8, 8 hr intervals significantly improved milk intake at feeding periods.