1. A trial was carried out with 96 purebred Large White and Landrace pigs to assess the optimum content of skimmed milk in diets given from 20 to 90 kg.

2. Pigs on treatment 1 (control) received a barley and soya bean diet providing 12·9 MJ digestible energy per kg and 161 g crude protein per kg until they reached 54 kg and 144 g crude protein per kg thereafter. Those on treatments 2 to 4 received 3·5, 4·5 and 5·75 1 skimmed milk per day, respectively, from 28 kg live weight, after a gradual increase from 2·0 I/day at 20 kg; this was given with a basal barley diet which provided 12·9 MJ digestible energy per kg and 111 g crude protein per kg. All diets were given according to scales to permit all pigs equal daily intakes of digestible energy. Treatments 1 and 2 were approximately isonitrogenous.

3. In order of treatment, average daily gains (g) were 658, 712, 743 and 737 (s.e. of difference, 15) and food: gain ratios were 3·06, 2·73, 2·63 and 2·60 (s.e. of difference, 0·05). There were no important treatment effects on linear carcass measurements.

4. It appeared that lysine supply was a major determinant of the results obtained.

5. The greatest daily gains were achieved when a minimum of 4·5 1 of skimmed milk was given daily with the basal diet; this approximates to an average skimmed milk: meal ratio of 2·8 I/kg.

Maturing patterns are established for the weight of bones relative to the weight of total bone and for the weight of fat depots relative to the weight of total body fat in two strains of Merino rams of different mature size. The maturing coefficients for all bone and fat depots are tabulated.

In the mature animals the partitioning of fat in each strain was similar, except for scrotal fat which was more abundant in the smaller strain. The maturity patterns of the depots were not different for the strains and also not different from the pattern of total fat, except in the case of scrotal fat. Accordingly, comparisons of the partitioning of fat were similar at equal maturity to the comparisons made at equal weight.

The distribution of weight among the bones was similar at maturity for both strains. However, unlike the fat depots, the individual bones had maturity coefficients which were mostly different from that of total bone. The limb bones, with the exception of the scapula, were early maturing relative to total bone. Accordingly, when compared at equal weight, limb bones, except the scapula, were a higher proportion of total bone weight in the larger strain and the differences between the strains were reduced when compared at equal maturity.

A summary of conclusions from this series of papers shows that tissues and organs had similar maturity coefficients in both strains of rams, and that stage of maturity was important in comparisons of proportions of tissues which have maturity coefficients which differed greatly from 1·0, but of little consequence where the maturity coefficient was close to 1·0

Wheat straw treated with 35 g NaOH per kg was offered to male calves at three levels: 300 (A), 500 (B), and 700 (C) g/kg diet, in a metabolism trial and in a feeding trial. In the former the wheat straw was offered either neutralized with HC1 (N) or unneutralized (U), in six subtreatments (AN, BN, CN, AU, BU and CU) in a 3 × 2 factorial design to a total of 24 calves. Dry-matter intake per kg W0·73 was 123, 108, 104, 122, 105 and 91 g/day, and the digestibility of the organic matter of the straw was 0·388, 0·616, 0·629, 0·385, 0·528 and 0·544 respectively. The apparent digestibility of the crude protein of the straw was negative. Nitrogen retention per kg W0·73 was 0·91, 0·58, 0·52, 0·97, 0·57 and 0·50 g/day, respectively.

In the feeding trial, unneutralized, NaOH-treated wheat straw was offered to a total of 84 calves for 100 days at the above three levels with two protein levels: standard, 120 g/kg (S) and high, 140 g/kg (H), in six subtreatments (AS, BS, CS, AH, BH and CH) in a 3 × 2 factorial design. The concentrates were pelleted. From day 101 to slaughter all the calves were offered one finishing diet.

Level of protein had no effect on performance. Increasing the levels of straw in the first 100 days sharply reduced average daily gains; these were 1 074, 825 and 583 g, respectively. However, the respective average daily gains on the finishing diet were 1 131, 1 272 and 1 316 g, indicating a considerable amount of compensatory growth.

The response of the growing female pig (25 to 55 kg live weight) to increasing dietary methionine plus cystine concentrations was assessed by measurement of growth rate, food utilization, ham dissection and changes in blood metabolite concentrations. A range of 13 methionine plus cystine concentrations from 3·5 to 5·79 g/kg resulting from combinations of three basal diets and synthetic methionine, was studied. The diets were formulated using barley, a yeast protein, tapioca and synthetic amino acids to contain similar energy concentrations, 9·5 g lysine per kg diet, and adequate concentrations of other essential amino acids and non-essential nitrogen. They were offered once daily according to a restricted feeding scale.

Responses were interpreted by broken line functions which indicated, from the growth performance experiment, a requirement between 4·5 and 4·8 g/kg of the diet, when the complete range of methionine plus cystine concentrations was studied. The influence of a range of dietary methionine plus cystine concentrations from 4·1 to 5·3 g/kg diet on changes in plasma urea, methionine, lysine and threonine concentrations indicated a requirement for methionine plus cystine of 4·5 g/kg of the diet.

Six ewes with twin lambs were allocated to each of six restricted feeding treatments with 10, 0·8, 0·6, 0·4, 0·2 or 0 of the diet as perennial ryegrass and the remainder as white clover, and to two treatments with either perennial ryegrass or white clover offered alone ad libitum. Fresh herbage was offered and measurements were made over 8 weeks, with the exception of the ad libitum clover treatment which was terminated after 5 weeks. All lambs were allowed access to clover from 14 days of age. Digestibilities of the herbages were measured during four periods in the experiment.

Increasing the proportion of clover in the diet significantly increased the intake of nitrogen by the ewes and the growth rate of their lambs, but had no effect on the live-weight changes of ewes on the restricted treatments. When there was no restriction of intake, ewes ate slightly more clover than ryegrass and lost less weight, but mean daily live-weight gains of their lambs over the first 5 weeks did not differ significantly (0·30 and 0·34 kg for ryegrass and clover, respectively).

When ryegrass and clover were eaten alone or together their organic matter digestibilities (OMD) did not change, although OMD declined with increasing level of intake.

Initial body condition of the ewes had a significant effect on the decline of ewe live weight and body condition during lactation, and on lamb live-weight gain

Wheat grain was given whole (W), cracked (C) or ammonia-treated (N) as the sole diet to six steers. In Expt 1, W, C and N were given at the rate of 2·1 kg per head per day. In Expt 2, W and N were given at the rate of 7·35 kg per head twice weekly; feeding of C had to be abandoned due to frequent bloat. Dry-matter digestibility was 0·79, 0·86 and 0·88 on W, C and N in Expt 1 and 0·75 and 0·83 on W and N in Expt 2.

The digestibility of neutral detergent fibre was 0·37, 0·24 and 0·57 with diets W, C and N respectively in Expt 1 and 0·27 and 0·47 with diets W and N in Expt 2.

The quantity of whole grain voided in faeces (g/kg grain fed) was 122, 3 and 31 with W, C and N in Expt 1 and 136 and 51 with W and N in Expt 2. Voided grains had a lower ratio of cr-glucose: neutral detergent fibre than grains fed, which indicated partial digestion of starch. Rates of nitrogen retention (g/day) were 6·6, 9·4 and 9·8 with W, C and N in Expt 1 and 7·2 and 12·2 with W and N in Expt 2.

It was concluded that ammonia-treated whole wheat grain is utilized as efficiently as cracked wheat grain when given as a sole diet to cattle and results in fewer digestive disturbances than cracked wheat grain.

The paper reports an experiment conducted with 50 Scottish Blackface and 10 South Country Cheviot ewes all suckling twin lambs and grazing, from parturition for some 18 weeks, pasture previously shown to cause a molybdenum-sulphur induced copper deficiency. The objectives were to examine the efficacy of various means of prophylaxis and the susceptibility of the two genotypes to copper deficiency.

The treatment of ewes at parturition with copper, either as an injection of 90 mg copper as copper methionate or orally with cupric oxide needles (3·2 g copper), delayed the onset of signs of copper deficiency in their lambs but did not prevent completely the development of hypocupraemia or hypocuprosis.

The treatment of lambs with a single injection of 15 mg copper as copper calcium edetate at about 6 or 10 weeks of age was not effective in preventing the development of hypocupraemia. Four injections (1 × 5 mg and 3 × 15 mg) at approximately equal intervals maintained normocupraemic values in lambs, but the most effective treatment, as judged by plasma and liver copper concentrations and by live-weight gain, was the administration of cupric oxide needles (1.6 g copper) to lambs at about 6 weeks of age.

The between-genotype comparison indicated that the Cheviot ewes and their lambs were as severely affected by the induced copper deficiency as were the Blackfaces.

Eighteen male and 18 female weaned rabbits were randomly allocated to two diets formulated to give energy concentrations of 8 (LE) and 10 (HE) MJ metabolizable energy per kg dry matter and three target slaughter weights (1·5, 2·25 and 3·0 kg live weight) to give a 2 × 2 × 3 factorial design with three replicates. Voluntary food intake and live-weight gain were monitored and the carcasses chemically analysed. The metabolizable energy concentrations of the diets were determined by balance and found to be 9·87 and 6·84 MJ/kg dry matter for diets HE and LE respectively.

Rabbits fed the LE diet consumed more dry matter (P < 0·001) and metabolizable energy (P < 0·01) in total, but grew more slowly than those fed the HE diet (P < 0·001). A diet × slaughter weight interaction occurred (P < 0·01); rabbits of the LE–3 kg treatment took longer to reach target weight as a result of a flattening of their growth curve.

Rabbits fed the LE diet had lower killing-out proportions (P < 0·05), heavier gut weights (P < 0·05) and gut contents (P < 0·05), but lighter livers than those fed the HE diet. Killing-out proportion progressively increased with increasing slaughter weight. External offal weight as a proportion of live weight tended to increase while internal offal weight as a proportion of live weight tended to decrease as slaughter weight increased. The carcasses of rabbits slaughtered at 3 kg had lower moisture contents (P < 0·001), greater fat contents (P < 0·001) and lower ash contents (P < 0·05) than other slaughter treatments. A significant diet × slaughter weight interaction occurred in fat content, with rabbits of the LE–3 kg treatment having proportionally more fat. With age at slaughter as a covariate, rabbits fed the HE diet had proportionally more fat (P < 0·05).

Medium-wool Australian Merino rams were sampled in 1978 and 1979 to estimate the relationships between the follicle curvature score, fleece and body characteristics.

As a high correlation coefficient between two independent observers was found in both years, only one observer was used to correlate follicle curvature score with wool production.

Repeatability of the follicle score between lambs at weaning and 14- to 15-month-old rams was 0·61*** and 0·65***.

Clean fleece weight was significantly correlated with greasy fleece weight (0·8***, 0·9***), clean scoured yield (0·6***, 0·7***), staple length (0·4*, 0·5**) and crimps per cm (-0·3, -0·4*), but the correlation was very low with fibre diameter (0·01, 0·06).

The correlation of clean fleece weight with body weight at 14 to 15 months varied between 0·2 and 0·5 (P < 0·001).

Follicle curvature score was significantly correlated with clean fleece weight (-0·5**), clean scoured yield (0·6***, 0·7***), staple length (-0·4*, -0·7***), fibre diameter (0·3, 0·6***) and crimps per cm (0·4*. 0·6***). Non-significant correlations of follicle curvature score with greasy fleece weight (–0·2) and body weight at 14 to 15 months (–0·04, –0·1) were found.

Depending on whether the proportion of superior 14- to 15-month-old rams which are to be retained for breeding is 0·10 or 0·05, then, according to our data, the proportion of lambs that can be culled at weaning (with an accuracy of P < 0·05) is 0·31 or 0·42, respectively.

Scottish Blackface (BF) and East Friesland × Scottish Blackface (EFX) ewes rearing single or twin lambs grazed for 14 weeks of lactation on two different pasture types in two consecutive years. Mean daily milk production, live-weight change and herbage intake of the ewes and live-weight gain of the lambs were measured each week.

In the first year the ewes grazed a ryegrass/clover sward. There were significant differences in milk production associated with breed of ewe and number of lambs reared. Peak yields, achieved in the 3rd or 4th week, reached 2·25, 2·5 and 3·25 kg/day for BF ewes with a single lamb and EFX ewes with single or twin lambs, respectively. Corresponding yields in the 14th week were 0·5, 1·35 and 1·15 kg/day. Live weight of ewes in all groups declined during the first 2 weeks but recovered by week 6. Herbage intake increased in all groups until the 8th week and then declined much more rapidly in the BF than in the EFX ewes. Lamb growth was related to milk intake to give weaning weights of 31·5, 39·0 and 29·0 kg, respectively.

In the second year, when ewes grazed a hill pasture dominated by an AgrostislFestuca community, differences in milk production, though significant, were smaller than in the previous year. Peak yields were 2·1, 2·25, 2·25 and 3·1 kg/day, respectively, for BF ewes with single or twin lambs and EFX ewes with single or twin lambs. At 14 weeks, yields had fallen to between 0·6 and 1·0 kg/day. The patterns of live-weight change and food intake were similar to those in the previous year. The EFX ewes consumed more food than BF ewes throughout lactation, particularly in the second half. Lamb growth rate was again related to milk supply and was lower than in the previous year. Weaning weights were 31·0, 25·5, 34·5 and 27·0 kg for single or twin lambs reared by BF or EFX ewes, respectively.

An experiment was performed to examine the effects of feeding four concentrations of crude protein in the diet to lactating rabbits. Diets A, B, C and D contained 173, 181, 224 and 243 g crude protein per kg dry matter respectively. Each diet was offered at one of two feeding levels: H (330 g/day) or L (280 g/day) with three replicates in each of the eight treatment groups. Milk production and nitrogen balance were measured over a 28-day lactation.

Although dry-matter intakes on feeding level H were significantly higher than those on feeding level L the difference diminished as the crude protein concentration decreased. The effect of crude protein intake on doe milk production was estimated therefore by regression analysis with digestible energy intake as a covariate. Both crude protein intake and digestible energy intake alone had significant effects (P < 0·001) on daily milk production and there was also a significant effect (P < 0·05) of crude protein intake after fitting digestible energy intake. Overall the equation was:

Milk production (g/day) =

17·61 + 0·985 crude protein intake (g/day) + 30·3 digestible energy intake (MJ/day).

(±0·448) (±14·8)

The relationship between digested nitrogen and nitrogen output as milk was also examined by regression analysis with digestible energy intake as a covariate. This equation was:

Nitrogen output in milk (g/day) =

0·438 + 0·164 digested nitrogen (g/day) + 0·572 digestible energy intake (MJ/day).

(±0·068) (±0·294)

The practical implications of feeding high levels of crude protein in the diet to increase milk production and pup weaning weight are discussed.

Seventy-nine Scottish Blackface and 79 North × South Country Cheviot ewes were fed to increase their mean condition score by 0·5 over periods of either 4 (M/H group) or 8 (I group) weeks prior to mating. Thereafter, they were fed a live-weight maintenance ration until they were slaughtered at 50 to 65 days after mating. Reproductive tracts were recovered, corpora lutea counted and embryos counted and examined. Plasma progesterone levels were monitored at selected times after mating. The proportion of ewes in each treatment group that were pregnant at the time of slaughter was similar (0·75 to 0·83) but there was evidence of differences in the pattern of reproductive failure with treatment. The proportion of non-pregnant ewes which had apparently been pregnant initially was 0·55 in the M/H group compared with only 0·27 in the I group. Circulating progesterone levels were not affected by premating nutritional treatments but differed with breed.

A rabbit nesting box incorporating a low wattage heated floor was developed. In a preliminary study a floor surface temperature in the box of 27°C was found to be adequate to minimize chilling of young pups in the nest. A full scale trial followed using 44 crossbred does, 22 provided with a nestbox containing a heated floor and 22 with a control plywood nesting box. The experiment continued for six successive reproductive cycles over the period April 1981 to February 1982 in an unheated rabbitry. Throughout the year significantly more pups reached weaning age when does were provided with nestboxes containing heated floors. On average, 0·15 of all pups born to does with heated floors had died by 28 days post partum, the comparable figure for unheated floors being 0·56. This reduction in mortality in heated boxes was apparent both on the day of birth and in the subsequent weeks prior to weaning. Ambient temperature and the wetness of the nest had a strong influence on the survival of pups in control boxes with high mortality rates experienced in the cold winter months (0·79 in February 1982). Most of these deaths in the control boxes were attributable to chilling and/or starvation in the nest (0·53 of diagnosed deaths overall). The running costs of the heated nestbox system are discussed.

Lamb mortality in a Scottish Blackface hill sheep flock subjected to long term selection for cannon bone length and fleece medullation score was investigated, using maximum likelihood analyses. The selection for cannon bone length and for medullation score had no significant effect on lamb mortality.

Two rations were prepared for sheep in which whole oat grain was mixed with molasses, urea, minerals and vitamins. Chemical analysis showed that the minerals had adhered to the grain and that there was little loss of minerals after one year of storage. The diets were readily consumed by sheep.

Sixty-nine rams of three crossing-ram breeds were mated on 11 farms over 3 years to produce crossbred ewes for a large field trial. Scottish Blackface and Welsh Mountain ewes mated to Bluefaced Leicester rams had larger litters at weaning than those mated to Border Leicester and the Animal Breeding Research Organisation's Damline rams. The crossbred Bluefaced Leicester lambs were heavier than the other crossbred lambs at both birth and weaning.

The intake of ten 5-year-old Masham ewes with good teeth, five 7-year-old Mashams with poor teeth and nine 10-year-old ewes with poor teeth was measured when they were offered long (35·1 cm) or short grass (3·8 cm) outdoors or poor quality hay indoors. The young ewes ate significantly more grass and hay than the old ewes, but the difference in daily intake was greater with long grass (1473 v. 751 g organic matter per head) and with hay (895 v. 421) than with short grass (617 v. 407). The intermediate age ewes ate as much of the long grass and of the hay as the young ewes, but less of the short grass. This suggests that age influenced intake more than did tooth condition, except when short grass was offered.

Within the oldest but not within the intermediate group of ewes, there was a significant correlation between the number of incisors and organic matter intake, except with the long grass, but there was no correlation between the number of cheek teeth and intake. When offered hay, the only group with a reduced in vivo digestibility was the intermediate group of ewes, the other two groups having a similar digestibility.

There was no correlation between number of incisors or number of molars and in vivo digestibility.

Lambs, 8 weeks of age, the offspring of sires of the Scottish Blackface, East Friesland, Finnish Landrace, Suffolk and Texel breeds mated to Scottish Blackface females as a common maternal breed were fed ad libitum on a concentrate containing barley and fish meal for 14 weeks. Live weight and food intake were measured at intervals of 2 weeks.

Live-weight gain varied between sire breeds, Suffolk crosses having the greatest growth rate and the Blackface lambs the least, but there were no significant differences in their food conversion ratios. Food intakes were compared with those predicted by two methods. When the only criteria for prediction were live weight and the metabolizability of the diet the prediction was poor, whereas very accurate agreement was found when the criteria for prediction included consideration of the changes in energy efficiency with food intake and with maturity.

Suckling post-partum cows treated for oestrous synchronization exhibited oestrus and became pregnant earlier in the mating period than untreated cows. Combined treatment with a progesterone-releasing device and prostaglandin F2α synchronized oestrus in a greater proportion of the cows than treatment with prostaglandin Fα alone (P < 0·01). The combined treatment appeared to induce ovarian activity in post-partum anoestrous cows that were approaching their first ovulation.