The study included 1013 gilts representing 28 one-way crosses among Yorkshire (Y), Landrace (Ld), Lacombe (Lc), Hampshire (H), Duroc (D), Berkshire (B), Large Black (LB) and Tamworth (T) breeds of swine. The crosses were distributed among five cooperating stations and were mated to Poland China boars to evaluate sow reproductivity based on the performance of the first two litters. The traits studied were weight at 112 days of age, age at puberty, percentage farrowing, litter size and weight at farrowing and at 3 weeks. Significant differences between crosses were found for all traits except farrowing percentage. The most prolific crosses were LdxY, HxLd and D x Y which gave birth to 11·0, 11·0 and 10·8 pigs per litter respectively, compared to the overall mean of 9·7 Ld x Y, LB x Lc and H x Ld crosses weaned litters 7·4, 5·3 and 4·9 kg heavier than the 40·5 kg mean for all crosses. Using percentage farrowing multiplied by litter 3-week-weight for the two litters as a measure of sow productivity, Ld x Y and LB x Lc crosses ranked highest. The breeds that had the best combining abilities for 3-week litter weight were Ld, Y, LB and Lc, however their specific combining abilities are important and hence not all crosses between these breeds produced superior performing crossbred sows. Overall, the Ld x Y was the most precocious, farrowed and weaned the greatest number of pigs per litter and had the heaviest litters at 3 weeks post-farrowing.

Reproductive and production traits were studied in a crossbreeding experiment involving Red Danish cattle, Indian milch breeds and native Zebu cattle in various combinations.

Frequency of abortions and postnatal mortality were higher for Red Danish than for Indian milch breeds and crossbreds, age at first calving was higher for Indian milch breeds than for other groups, calving interval was longer for purebreds than for crossbreds. Milk and butterfat production in first and second lactation increased with increasing proportion of genes from Red Danish cattle. The range of milk production in first lactation was from 987 kg for Indian milch breeds to 3445 kg for Red Danish imported from Denmark.

The optimum proportion of genes from Red Danish for the environmental conditions prevailing in the present crossbreeding experiment is considered to be 60 to 80%.

The growth of 12 linear body measurements in Ayrshire cattle was analysed by least-squares methods. Measurements were taken at 3-monthly intervals up to 48 mo of age. Adjustments were made for month and year of birth and for type of birth (twin-born animals comprised 40% of the data). The state of pregnancy or lactation in heifers was also taken in account. Growth curves were fitted to the mean values at the 16 ages and were found to give a close fit. Residual deviations, though small, did show a systematic pattern. The estimated degree of maturity at birth ranged from about 25% for measures of width to 50% for measures of height, body length being intermediate at 40%.

To a large extent the different body measurements maintained a uniform pattern of maturing and their ranking for earliness of maturity tended to remain constant throughout the growth period. The application of allometry to the measurements is examined and the error introduced by extrapolating an allometric relationship between characters of different maturing rates is illustrated.

Data on 2208 parturitions involving 3594 kids were used to study the inheritance of polledness and its relationship with intersexuality in the Damascus breed of goat.

The percentage of horned kids in the offspring of polled × polled and horned × horned matings was 26·8 and 100·0, respectively. The corresponding value for matings having one parent horned was 50·3%.

There was a consistent excess of males in the sex ratios. Males comprised 53·8, 52·4, 60·2 and 54·0% of the offspring of polled x polled, polled x horned, horned x polled and horned × horned matings respectively. The corresponding proportions for the intersexes were 6·2, 0·3, 0·0 and 0·0%. The incidence of intersexes was not affected by type of birth (single, twin or multiple) or sex of littermates.

It was concluded that the data from the Damascus breed of goat conform with the current theory on the behaviour of the P gene concerning polledness (direct dominant effect) and intersexuality (pleiotropic recessive effect) in the Swiss breeds of goat.

Observations were made on a commercial herd of female pigs (sows) where a managemental system was employed which enabled sows to be served during lactation. The system involved grouping between 2 and 8 sows together with their litters about 3 weeks post partum. The sows were fed ad libitum from grouping, and the piglets had ready access to creep food. After one day a male pig was introduced to the group. No exogenous hormone therapy was used.

Results from 39 batches, comprising 180 sows, suggested that sows kept under these conditions will exhibit oestrus, and conceive during lactation with a high degree of predictability. Lactational oestrus was shown by all sows and conception to first service was 84·9%. The number of days between grouping and oestrus, and parturition and oestrus, were 11·15 ±0·28 and 35·53 ±0·47 respectively. Litter size and performance did not appear to be adversely affected by the concurrent lactation and pregnancy, either at the present or subsequent parturition. The average farrowing interval of 153 days allowed a performance of 2·35 litters/sow per year, and, with 9·47 piglets weaned/litter, a productivity of 22 piglets/sow per year.

Records for 6012 inseminations of cows were analysed to determine the effect of the stage of oestrus at the time of insemination on conception rates for three groups of sires. All inseminations were completed between 8.30 hr and 11.30 hr using 2·5 million total spermatozoa in 0·5 ml of ‘Caprogen’ extender containing catalase. The designation of the stage of oestrus was based on the milking or milkings relative to the time of insemination at which each cow was observed in oestrus. Data from cows returning to service less than 18 days after insemination were excluded.

The average conception rates (18 to 49 day% non-return rate) for the three groups of sires were 72·9% (7 sires of above average fertility), 70·5% (5 sires of average fertility), and 68·3% (6 sires of below average fertility). With inseminations in early oestrus, the comparable results were 74·3, 62·7 and 58·4% respectively. In contrast, the results for the three groups of sires with post-oestrous inseminations were 73·3, 71·13 and 73·8% respectively.

The average interval from insemination to ovulation and fertilization is related to the stage of oestrus at insemination. This interval was the major factor contributing to the fertility differences between the groups of sires included in this experiment. These differences were also reflected in the percentage and distribution of normal (18 to 24 day) return intervals.

In the first experiment, 10 ewes (¼ Finnish Landrace: ¾ Clun Forest) were maintained under natural daylength conditions and 10 were exposed to a constant daylength of 8 hr from 22 December until 1 June. No difference was demonstrated between treatments in dates of cessation of oestrous activity. It was concluded that oestrous activity will eventually cease, whether or not daylength increases after the shortest day.

In the second experiment, 40 similar ewes were mated at first oestrus of the natural breeding season (mean 7 September) and lambed in January. Twenty ewes suckled lambs and 20 had lambs removed within 24 hr of birth. No sucked ewes showed oestrus before the end of the breeding season, but 9 non-sucked ewes showed oestrus at a mean interval of 37·5 days after lambing and 4 of these subsequently lambed. Suckling appeared to inhibit oestrous activity and conception in ewes at this time of year.

In a study involving over 300 pelves from lambs of known age at slaughter it was shown that time of ossification was poorly related to age of lamb. The youngest lamb with an ossified pelvis was a female aged 22·4 weeks and at the other end of the scale a third of a group of 45-week-old castrated male lamb pelves were not ossified. Female lamb pelves ossified earlier than castrated male lamb pelves. Carcasses with ossified pelves at a given age tended to be heavier than those with pelves not ossified and pelves of well-fed lambs probably ossified before those of poorly fed lambs. The results indicate that the suggested Codex method for a carcass classification or grading system for dividing lamb carcasses into those under and those over 6 mo of age at slaughter was not accurate. The reason for wanting such a classification is also questioned.

Data on incidence and severity of infection with bovine infectious keratoconjunctivitis and proportion of eye margin pigmentation were collected over 3 years in a mixed herd of Hereford × Shorthorn (HS), Africander x HS, Brahman x HS, grade Africanders and purebred Brahmans. Both sexes were scored at 3 and 8 mo but only females were scored at 15 mo. At all ages, the incidence of infection was greatest in the HS and lowest in the Brahmans in which no infections were recorded. The severity of infection and proportion of bilateral infections were also greatest in the HS animals.

Infected animals were lighter at all ages than comparable uninfected animals. HS females which showed signs of infection at each age were 22·8 kg lighter at 15 mo than those which had never shown signs of being infected. The magnitude of the weight difference was directly related to the severity of infection.

In the HS breed, both the incidence and severity of infection were related to the proportion of eye margin pigmentation. At 15 mo, 68% of HS females with full eye margin pigmentation were infected compared to 96% of comparable unpigmented animals. At 15 mo infected HS females with full eye margin pigmentation were heavier than unpigmented contemporaries. It was concluded that the lower weight of infected animals was primarily the result of the disease rather than vice versa.

Digestible energy (DE) values were determined for 15 pig diets with pigs 8 to 18 weeks old by standard digestibility procedures. The 15 diets contained 4360 to 4920 kcal gross energy (GE)/kg dry matter (DM), 2750 to 4070 kcal DE/kg DM, 2·8 to 15·8% crude fibre (CF), 2·4 to 21·1% acid-detergent fibre (ADF), and 7·3 to 33·8% neutraldetergent fibre (NDF).

The prediction equations obtained were all highly significant. DE was most accurately predicted when the fibre value used was NDF, the regression equation being: DE = 4314·37·22 NDF (residual SD + 265). The inclusion of GE in the regression equation considerably improved its accuracy: DE = 1·510 GE-2579·39·37 NDF (residual SD ±127).

However, the greater digestibility by pigs of NDF in diets containing sweet lupin seed meal (SLSM) resulted in these diets being more efficiently digested than diets containing other common protein supplements. Omitting the four diets containing SLSM from the regression analysis resulted in an even more accurate prediction equation: DE = 1·177 GE-1085·40·22 NDF (residual SD±107). It is suggested that this equation may be used to predict DE of pig diets compounded from commonly used constituents.

Fifty-four pigs weaned at 3 weeks of age were allocated at an average weight of 5·4 kg to two experiments to examine the effects of diets having digestible energy (DE) concentrations ranging from 2910 to 3940 kcal/kg.

In the first experiment pig growth performance and the dry-matter digestibility of the experimental diets were measured between 3 and 8 weeks of age. The composition of the carcass at 8 weeks of age was correlated with the composition of various carcass joints.

In the second experiment pig growth performance was measured over the live-weight range 5-4 to 20 kg.

The findings were:

1. Growth rate was linearly related to DE intake.

2. The optimum DE level for maximum growth was 3640 kcal/kg.

3. The efficiency of utilization of DE for growth did not vary in the first experiment but was poorest at a DE concentration of 3245 kcal/kg in the second.

4. The DE content of the diet had no significant effect on carcass characteristics at 8 weeks of age in the first experiment or at 20 kg live weight in the second.

5. The proportion of fat and lean in the 8-week carcass was significantly (P < 0·01) correlated with that of the shoulder joint.

Growth performance and carcass quality (linear measurements) were studied in pigs grown from 25 to 90 kg on barley stored and prepared in different ways. Half the barley was dried to about 14% moisture content for storage and half was not dried but treated with 0·8% propionic acid. Each was given after hammer-milling (3·2 mm screen) or rolling. A total of 144 pigs was used at four centres.

The performance and carcass quality of pigs given acid-treated barley were as good as those given dried barley. While feed utilization, expressed on the basis of air-dry feed, was poorer for pigs fed on acid-treated barley this difference disappeared when account was taken of the different moisture contents of the barley samples. Pigs fed on diets based on milled barley grew more quickly, had better feed utilization but greater fat measurements than pigs fed on rolled barley. There was a significant interaction between storage method and feed preparation (milling or rolling). Pigs given the acid-treated barley grew more quickly when it was in the milled form than when it was rolled, whereas for the dried barley there was a small, non-significant difference in favour of the rolled form.

In 1972 a comparison was made between rotational creep grazing (R—8 paddocks) and set stocking (S—2 paddocks) for ewes and their twin lambs at 3 stocking rates viz. 20 (H), 17 (M) and 14 (L) ewes/ha.

The herbage intakes/kg live weight of the R ewes were similar to those of the S ewes in period 1 (c. 7th week of lactation) but higher i n period 2 (c. 10th week of lactation). The intakes of the lambs were not affected by the grazing management in periods 3 or 5, but in period 4 the R lambs had a higher intake than those on S. The overall lamb growth rates were also higher on R compared with S. The carcass outputs (net of supplementary feed) were higher for any R treatment compared with any S treatment being 453, 451 and 427 for R and 419, 379 and 380 for S at the H, M and L stocking rates respectively.

1. Four experiments have been carried out to determine the effect of treatment of spring-sown barley straw (var. Deba Abed) with sodium hydroxide (NaOH) solution and subsequent neutralization with hydrochloric acid (HCl) on its digestibility and intake by sheep.

2. In Experiment 1, chopped straw was mixed with 4·5 or 9·0 g NaOH in 200 or 800 ml water/100 g, straw, and after 24 hr neutralized with HCl and left for a further 24 hr before being offered to castrated male sheep (wethers) in a maintenance diet containing 35% concentrates. Organic-matter digestibility of straw significantly increased, by 8 and 11 percentage units respectively, after treatment with 200 ml solution containing 4·5 and 9·0 g NaOH. Volume of solution did not affect digestibility.

3. In Experiment 2, straw treated as in Experiment 1 was given ad libitum. The highest intake was for straw treated with 200 ml solution containing 4·5 g NaOH/100 g straw, treatment with 9·0 g NaOH giving a significantly lower intake but higher than that of untreated straw.

4. In Experiment 3, the in vitro digestibility of milled straw, treated as in Experiments 1 and 4, increased with increasing volumes of solution up to 120 ml/100 g straw, but the response to successive increments of NaOH declined progressively.

5. In Experiment 4 chopped straw was mixed with 4·5, 6·75 or 9·0 g NaOH in 30, 60 or 120 ml water/100 g straw and offered as in Experiment 1. Treatments significantly increased straw digestibility, by 8 to 16 percentage units. Increasing the volume of water from 30 to 60 ml significantly improved digestibility, by 5 percentage units at the two lower levels of NaOH. The response to an increase in the level of NaOH was less, and inconsistent. In vitro and in vivo digestibilities were significantly correlated, but it is concluded that the in vitro technique used overestimates the digestibility of treated straw.

The effect of three moisture concentrations (10, 50 and 75%) and of four fermentation conditions (none, 24 hr aerobic, and 24 and 48 hr anaerobic) on the nutritive value of two complete fattening diets containing 25 and 45% poor roughage, was examined in three digestion and nitrogen balance trials, each of Latin square design, in cattle.

Fermentation increased the lactic acid and volatile fatty acid concentrations of the feed, decreased its pH and the crude fibre content, and caused losses of dry matter.

There were non-significant differences in voluntary intake between the dry and soaked diets. The apparent digestibility of dry and organic matter, crude protein, nitrogen-free extract and crude fibre was non-significantly improved by added moisture. There were no consistent differences in nitrogen retention.

The average metabolizable energy values (ME) observed for both diets were 6% higher than those calculated. There were no significant differences in the apparent digestibility of gross energy or in ME value between treatments of different moisture content.

The fluctuations in pH of rumen liquor during the day differed markedly when the animals received different levels of roughage. These differences were greater when the feed was allowed to ferment. Soaking of feed resulted in a significant increase in the concentration of propionic acid in the rumen liquor, and a non-significant decrease in that of acetic acid. Consequently the C2/C3 ratio was significantly lower on the moist feed treatments.

There were no consistent differences in concentration of ammonia in the rumen liquor, or of urea in the blood.

In a trial involving 231 pigs grown from 20 to 90 kg live weight, three methods of adjusting the feed allowance were compared, namely according to live weight and a scale with weekly adjustments, or according to age with fixed increments of feed, adjusted either weekly or every 3 weeks. Irrespective of the frequency of feed adjustment, rationing by age gave as satisfactory results in performance and carcass quality as rationing by live weight, and reduced labour requirements by eliminating the need for regular weighing of the pigs throughout the growing period.

Two levels of feeding were offered at each of two air temperatures, 25° or 33°C, to pigs while they grew from 20 to 70 kg live weight; two pigs were subjected to each of the four treatments. Significant increases occurred in the urinary excretion of Ca and K by the two pigs fed on the higher level and exposed to 33°C. However these effects could not be related in an obvious way to the lameness which developed in the latter pigs.

One hundred and twenty-four young rabbits of the Giant of Spain breed (mature weight, 4 to 4·5 kg) were slaughtered in groups at birth, 10, 20, 30, 40, 50 and 60 days of age.

Energy retention over the six 10-day periods was 10·7, 26·5, 39·0, 48·9, 72·6 and 57·3 kcal/day, energy content per unit of weight increase was 5·18, 5·52, 5·52, 5·47, 5·80 and 5·89 kcal/g, and deposition of protein (N×6×25) was 1×45, 3×09, 4×28, 5×56, 7×31 and 5×44 g/day. The regression of the energy content of the empty body (kcal) on empty-body weight (g) was:

Y = 1×734 X – 88·536

with a coefficient of regression of 0·97.

ANIMAL PRODUCTION, Volume 20, part 3, p. 426