One hundred and forty-four Large White weaner pigs were used in each of two experiments to investigate the nutritive value of liquid separated milk. Two experimental diets, one based on separated milk and barley meal, the other on separated milk, soya bean meal and barley meal were compared with control meals of the type used in the Pig Industry Development Authority's progeny testing stations. The amounts of milk in the experimental diets were adjusted so that the lysine concentrations in the dietary dry matter were similar to those of the control meals. All diets were given according to a restricted scale relating daily dry matter allowance to live weight, to a scale relating digestible energy allowance to live weight and to ‘appetite’. In the first experiment, pigs were slaughtered at 200 lb live weight, in the second at 260 lb live weight.

Pigs given the separated milk and barley meal diet performed similarly to those given the control meals; those given the separated milk, soya bean meal and barley meal diet had better feed conversion efficiencies than control pigs, particularly over the range 200 to 260 lb live weight. Pigs given diets containing milk had higher killing-out percentages and shorter carcasses than those given the control meals. Diet had no statistically significant effect on the percentages of fat and lean in the sides.

The effects of plane of nutrition were demonstrated by the faster rate of gain and poorer carcass quality of pigs fed to ‘appetite’.

It was concluded that the nutritive value of separated milk is explained by its high energy and lysine content. There was no evidence of any unknown beneficial factor in it.

Closely shorn Scottish Blackface female sheep aged 9–14 months, half on high plane and half on low plane nutrition, were subjected, in climate chambers, to two short acute cold exposures down to −20°C. The acute exposures were separated by two weeks chronic exposure to a moderately subcriticai temperature (+8°C) or to a thermoneutral temperature (+30°C). Most of the sheep showed a greater resistance to body cooling at the second acute exposure (Slee and Sykes, 1967). This increased resistance to hypothermia, defined as acclimatization, was apparently influenced more by acute than by chronic cold exposure. The present paper deals with changes in skin temperature, heart rate, shivering intensity and skinfold thickness which also resulted from cold exposure, and accompanied acclimatization.

After acute cold exposure followed by chronic exposure to +8°C the following changes in these parameters were observed:

1. Extremity skin temperatures and heart rates were consistently increased at thermoneutral ambient temperatures.

2. Vasoconstriction of the extremities and increased heart rate, both of which normally occur during the early stages of cold exposure, were delayed.

3. Heart rates at sub-zero ambient temperatures were increased.

4. Cold-induced vasodilatation at sub-zero ambient temperatures was increased.

After acute cold treatment alone the intensity of shivering during the second acute exposure was reduced. Also the onset of foot vasoconstriction was slightly delayed.

A highly significant relationship was observed between shivering intensity and heart rate during cold exposure.

Plane of nutrition had less effect on the physiological responses to cooling than did previous cold experience.

It was suggested in discussion that the physiological responses associated with acclimatization were: elevated basal metabolic rate, delayed onset of vasoconstriction and delayed metabolic response to cold, and consequent lowering of the critical temperature. Summit metabolism was also increased and shivering intensity reduced during acute cold exposure. Some of these responses could have resulted from either acute or chronic moderate cold exposure. However their persistence, once induced, appeared to depend upon continued exposure to moderate cold.

1. Two growth trials and digestibility trials were carried out with 54 steers given diets containing either 11%, 14% or 17% crude protein in the dry matter and the same concentration of metabolisable energy.

2. There were no significant differences in either dry-matter intake or live-weight gain by the steers given the diets containing 14% or 17% crude protein. Dry-matter intake was lower for the steers given the diet containing 11% crude protein and their live-weight gain was lower up to 250 kg live weight. Beyond 250 kg live weight their live-weight gain was similar to that of the steers on the two other treatments.

3. Both dry-matter digestibility and apparent nitrogen digestibility were lowest for those steers given the diet containing 11% crude protein.

Live weight of 180 free-grazing Blackface ewes was measured approxim-ately every two weeks throughout a 12-month period. Mean live weight was at a maximum (47 kg) in late autumn prior to mating and declined progressively to 39 kg at about the time of parturition.

Six ewes were slaughtered in November before mating, six at about the 16th week of pregnancy, and a further 11 in April during the final week of pregnancy. The loss of weight of maternal tissues (i.e. live weight less the weight of fleece and contents of the gastrointestinal tract and gravid uterus) during this period was more than 20% (7·5 kg) and comprised 51% of the fat, 14% of the water, and 20% of the protein plus ash present at maximum live weight. During the earlier stages of pregnancy there was an appreciable loss of water from the maternal tissues, but in late pregnancy the rate of water loss decreased and that of fat increased considerably.

The distribution of fat throughout the maternal tissues at different levels of total fat content and the pattern of fat mobilization from various depots are described. The largest single contribution to fat loss during the pregnancy period was that of the subcutaneous reserves, which were depleted by 86%, most of this being lost during the first four months. At the other end of the scale bone fat reserves were reduced by only 25%, almost all of this occurring during the final month.

Chemical and physical compositions were respectively determined on right and left sides of 23 Scottish Blackface ewe carcasses. Relationships were derived whereby physical carcass composition, in terms of muscular tissue plus associated fatty tissue, subcutaneous plus perirenal fatty tissues, and bone, could be estimated from weights of chemically determined water, fat, ash, and fat-free dry matter. The use of these relationships is discussed, and it is suggested that in certain circumstances the estimation of physical carcass composition from chemically determined components could result in considerable economies of time and labour.

The use of certain readily determined physical components as indices of the chemical composition of the whole body is considered, and relevant prediction equations presented.

1. Experiments were done to assess the reaction of sheep to small artificial shelters and to study the effect of these shelters on the live-weight gain of young lambs in the springs of 1958, 1959 and 1960.

2. Lambs sought shelter particularly when it was raining. They were sensitive to high wind speed and low temperature but did not usually shelter in mild dry weather.

3. Ewes were indifferent to rain and remained in the open in wet weather while many of their lambs sheltered. They occasionally used the shelters for shade in warm sunny weather when their lambs usually went with them.

4. Because of these differences between ewes and lambs in their response to shelter, during wet weather ewes were less closely associated with their lambs where they had access to shelter than where there was no shelter.

5. In the wet spring of 1958, lambs with access to shelter gained weight more slowly than those without shelter. It is postulated that the lambs with shelter may have consumed less milk than the others due to a weaker social bond with their dams.

6. None of the experiments showed that shelter improved the live-weight performance of young lambs.

Blood serum free fatty acid (FFA) levels have been measured in sheep subjected to: (a) short periods (20–24 hours) of fasting, (b) physical and emotional disturbances associated with experimental handling, and (c) exposure to cold temperatures when either pregnant or unmated.

The first two factors acted additively, each causing a small elevation of about 100–200 μ-equiv/litre above the pre-existing FFA level. The effect of short-fasting gradually disappeared during the first 6 hours after feeding; the effect of experimental disturbance lasted less than 2 hours.

The effect of severe cold treatment (exposure to approximately 60°C subcriticai ambient temperatures for 2–10 hours) was very marked, producing mean FFA elevations of about 2000 μ-equiv/litre.

Mild cold exposure (3−8°C below the critical temperature), even when maintained for several days, produced little change in the FFA levels already typical of either well-fed or short-fasted sheep. Exposures of moderate intensity (25°C below the critical temperature) apparently produced small elevations in short-fasted sheep only.

It was concluded that a large increase in FFA level was the normal response to acute cold exposure. Elevations due to other factors were, in the context of these experiments, very small. Within the normal range of response to cold exposure there was considerable individual variation in the degree of FFA elevation, but this variation was not generally related to cold resistance expressed as the ability to maintain rectal temperature. However, a few sheep which failed to raise FFA values to the normal extent did show poor cold resistance.

A method for performance testing beef bulls on a high-energy diet from 90 days of age to 400 kg is described. Test results for 81 bulls showed that both in weight-for-age at 400 kg and feed conversion on test there were significant differences between breeds in favour of the Charolais followed by Santa Gertrudis, Criollo and Zebu in that order. Results for 8 Holstein bulls reared artificially were similar to those for Santa Gertrudis.

Comparative data on birth weights, weaning weights and pre-weaning mortality indicate that the Zebu was inferior to the other beef breeds in all these traits.

Of 60 bulls slaughtered, liver abscesses were encountered in only 2 animals, both of which had been reared artificially from birth.

1. Twenty-seven Large White pigs from three litters were involved in a 33 factorial experiment in which they were given three pelleted diets containing 0, 10% and 20% of dry sawdust during each third of an experimental period ranging from 29·5 to 118 kg live weight. The effects of these treatments on dry-matter intake and rate of growth in each sub-period and on the final carcass quality of the pig were studied.

2. The results confirmed a previous finding that pigs developed a compensatory increase in intake in response to diets containing increasing amounts of sawdust, but that in small pigs this operates very poorly and leads to much retarded growth on the high sawdust diets.

3. The compensatory intake mechanism took some time to develop after the pig had been put on to the sawdust diets, the delay being much longer in the smaller pig. Similarly, when the pigs were returned to high energy diets some time elapsed before intake returned to normal. During this time lag the pigs grew faster, as with compensatory growth, than when they had not previously been subjected to low energy diets.

4. It is concluded that long-term observations must be made in order to investigate the nutrition of pigs fed ad libitum.

5. Although energy intake can be restricted by giving low energy diets for a short period, this does not seem to improve carcass quality.

A study of variation in milk yield and butterfat has been undertaken, using the test station records of almost 5 000 first-calf cows of three dairy breeds.

The general object of the investigation was to provide a background for a more comprehensive examination of the important productive characteristics of dairy cattle, and of the use of different sire-testing procedures for their improvement; the specific object was to consider the possible causes of large sire components and heritability estimates that have been observed in all analyses of test station production data, and the reasons why the station and field tests of a bull do not always correspond.

Large heritability estimates for milk yield, fat yield and fat percentage were obtained in the Danish Red and Black Pied breeds, but the corresponding estimates in the Jerseys (0·31, 0·48 and 0·58 respectively) were similar in size to the values normally obtained for these traits in field data.

The pre-selection of heifer recruits to the stations, and breed differences in the intensity of selection applied to the productive characteristics, were considered and dismissed as causes of abnormal sire components, in the light of results obtained from field data which indicated that the heritability of milk yield in the Jerseys was not lower than in the other two breeds (0·26, 0·37 and 0·36 in Danish Reds, Black Pied and Jersey).

It was suggested that differences between records made in test stations and records made in farmers' herds may be caused by differences in milking efficiency, by differences in culling practices in the two environments, and by the effects of age, season at calving and contemporaneity. Other investigations have established that these factors may have a large influence on the variance components of the production traits, and all of them would repay further investigation.

1. Bulls and steers of the Yugoslav Simmental breed (38 in total) were reared and fattened to 470 kg live weight. Half received a moderate level of feeding to 8 months of age and half a high level of feeding over this period; all were fed on a high level from 8 months to slaughter, their diet involving a concentrate mixture, lucerne hay and maize silage.

2. At slaughter weight, steers were 2·5% higher at withers than bulls, but other body measurements showed no significant difference.

3. Castrates needed a 3 to 8% longer fattening period depending on the feeding treatment.

4. Castration reduced the rate of live-weight gain by 4·9% over the whole rearing and fattening period, and by 8·0% over the fattening period only.

5. Bulls had better feed conversion ratios overall. Steers consumed more starch units per kg of live-weight gain—8·1% more over the whole rearing and fattening period and 9·8% over the fattening period. Consumption of digestible crude protein was also higher in steers.

6. The detrimental effect of castration was more strongly expressed on the HH feeding treatment. An increase in the concentration of the rations did not improve food conversion ratios.

There were 563 lambs in the study. They were single Barki lambs born during the period 1961–62 to 1965–66 in Ras El-Hekma Desert Research Station (U.A.R.). All lambs were weighed at birth and at weaning. From 1963–64 onward lambs were weighed nearly every 15 days.

Two methods of estimating growth rate were compared:

R1 = weaning weight — birth weight/age at weaning

and R2 = the regression coefficient of weight on age. The effect of method of estimation on heritabilities and genetic and phenotypic correlations was examined.

Heritability estimates of birth weight, R1 and genetic and phenotypic correlations between them were 0·18 ± 0·10, 0·24 ± 0·11, 0·50 and 0·12 respectively. From the data collected during the period 1963–64 to 1965–66 alone the heritability estimates of birth weight, R1 and R2 and the genetic and phenotypic correlations between birth weight and each of R1 and R2 were 0·15 ± 0·14, 0·39 ± 0·20 and 0·39 ± 0·20; 0·84 and 0·96; 0·28 and 0·27 respectively.

For preweaning growth rate the method of dividing the gain in weight until weaning by age at weaning was virtually as good a method as using the regression of body weight on age. The correlation between the two methods was estimated as 0·91.

Early weaning is now a well recognized and widely practised system of calf rearing which saves considerable labour compared with the former practice of giving liquid milk or milk substitutes in buckets twice daily to the age of 12 weeks.

One of the practical difficulties of bucket feeding calves twice daily is that the feeding times need to be close to the beginning and end of the stockman's working day to maintain reasonable intervals between intakes of liquid. Each feed must be followed by further time spent washing utensils. The labour demand for this can often conflict with that for milking and feeding other stock. It seemed possible that the whole of the liquid milk substitute intake of calves destined for early weaning might be provided in one feed daily with considerable saving of labour and increase in convenience.

From time to time in the United Kingdom and other countries skim-milk is locally in plentiful supply and very moderately priced. It is of course successfully utilised in the fattening of pigs, but it seemed to us that it might also be a useful feed for store sheep. Two feasibility studies were therefore carried out in 1964.

Weaning lambs at 8 to 10 weeks of age is widely practised in the U.S.A. The practice results in the ewes being dry for relatively long periods and affords an opportunity to reduce feed costs during that time. Jordan and Hanke (1964) maintained non-lactating ewes in drylot on 2 to 2·5 lb of legume hay per ewe daily, and Jordan and Marten (1965) doubled the number of ewe grazing days (carrying capacity) by restricting the time the ewes were permitted to graze per week to about 50% of normal. In neither study was subsequent wool or lamb production reduced.

The Milk Marketing Board's 23 artificial insemination (AI) centres which provide service in much of England and Wales are grouped into five geographical areas (Figure 1). Analyses of trials on commercial farms to study the effects of crossing Charolais bulls with dairy cows (Edwards et al. 1966), revealed significant differences between these areas in both gestation length and birth weight of crossbred calves. However, the Charolais bulls used in the trials were divided into five teams, each of three bulls, and each team was used only in a single area. Consequently, bull teams and areas were confounded. The purpose of the experiment reported here was to estimate the differences between areas in gestation length and birth weight independent of sire.