Properties of the non-carcass parts in combination with empty body and half carcass weight (EBW and CCW; kg) were used to generate equations for predicting empty body chemical composition. Therefore, chemical composition of the non-carcass parts and weight of the depot fatty tissues were determined on 18 Belgian Blue double-muscled fattening bulls. Very high coefficients of determination (R2) were found between the empty body composition and on the one hand the non-carcass parts composition and on the other hand the weight of the fatty tissues. Fat in the empty body was most difficult to predict. The very high coefficients of determination are partly caused by the large variation in slaughter weight (309 to 723 kg). Therefore equations to estimate proportional composition of the empty body are discussed. Although R2 values are strongly reduced, residual standard deviations remain very low and the precision of prediction is good. The proportion of protein is most difficult to predict, as it shows a very small variation. Estimations based on composition of the non-carcass parts are mostly a little more precise than the estimates based on weight of the fatty tissues but as the latter are much easier to determine, these equations will be more appropriate for practical use. Similarly the little improvement of the estimation based on EBW instead of CCW, cannot account for the extra costs and time to determine EBW. The results of the homogenizations have proven that there is very little variation in composition, despite the large range in slaughter weight. As the Belgian Blue double-muscled animals are very deviant from other breeds, the equations found in this study can only be applied for this breed type.

Milk replacers in which skim milk protein (SMP) was replaced in various proportions by undried or dried fish protein hydrolysate (FPH) were offered twice daily to British Friesian male calves. Various proportions of fish protein and milk protein in the diets were obtained by mixing replacer made from SMP with replacers made from undried and dried FPH respectively. The ratios were: 100 FPH, 0 SMP; 67 FPH, 33 SMP; 33 FPH, 67 SMP; and 0 FPH, 100 SMP. Calves were offered the milk replacers only to a maximum of 5 1 per day until 28 days when concentrates and hay were offered ad libitum. The calves were weaned after 42 days. Feed intake and live-weight gain were recorded for 84 days.

There was a marked decrease in performance to weaning when the milk replacer contained two-thirds or more of the FPH. The FPH-fed calves had lower hay intakes than those fed milk only. Treatment differences in post-weaning live-weight gain reflected mainly differences in concentrate intake. There was no significant difference in live-weight gain nor food efficiency for calves fed either undried or dried FPH in any period to 84 days. The number of treatments for scour was similar for the two groups. However, the calves fed dried FPH had a lower dry-matter intake in the post-weaning period.

The effect of intramuscular injections of vitamin E on growth, carcass traits, intramuscular collagen (IMC) characteristics and decorin of growing lambs was studied. A total of 24 15-day-old Ile de France suckling male lambs were divided into two groups and weekly intramuscular injections of DL-α-tocopheryl acetate (control group, 0 IU; Vitamin E treatment, 150 IU) were given until the lambs were 64 days old. Lambs were individually weighted at 15, 29, 43, 57 days of age and at slaughter (71 days old). Dry matter intake and average daily weight gain were recorded. Hot and cold carcass weights were recorded and dressing percentages were calculated after dressing and chilling (2°C to 4°C for 24 h). Carcass shrink losses were calculated as well. Longissimus muscle (LM) pH and area were measured. The pelvic limb was removed and its percentage was calculated based on cold carcass weight. IMC and decorin analyses were assessed on LM and semimembranosus muscle (SM). DL-α-tocopheryl acetate treatment reduced (P<0.05) collagen maturity and increased (P<0.05) decorin in both LM and SM muscles of growing lambs, while it did not affect IMC content. In addition, vitamin E did not influence growth, carcass weight, dressing percentage, carcass shrink losses and area of LM but decreased (P<0.05) the pelvic limb percentage. The LM pH values were higher (P<0.05) in vitamin group than in control group. Furthermore, different IMC characteristics between the muscles (P<0.01) were apparent. Multiple intramuscular injections of DL-α-tocopheryl acetate influence extracellular matrix in lambs, which could affect meat tenderness.

A high-fat diet is known to induce atherosclerosis in animal models. Dietary factors and timing of atherogenic food delivery may affect plasma lipoprotein content composition and its potential atherogenic effect. Increasingly often, humans spend periods/days eating in a completely unregulated way, ingesting excessive amounts of food rich in oils and fats, alternating with periods/days when food intake is more or less correct. We investigate the effect on lipid homeostasis of a high-fat diet administered either continuously or intermittently. We investigated control pigs receiving standard diet (C, n=7), pigs receiving a high-fat diet every day for 10 weeks (CHF, n=5), and pigs receiving a high-fat diet every other week for 10 weeks (IHF, n=7). IHF animals were shown to have a different lipid profile compared with CHF animals, with a significant increase in high-density lipoproteins (HDL) levels with respect to C and CHF groups. CHF also showed significantly higher values of TC/HDL cholesterol compared with C and IHF. Hepatic expression analysis of genes involved in lipid homeostasis showed an increasing trend of nuclear receptor LXRα along with its target genes in the CHF group and in the IHF group, whereas SREBP2 and LDLr were significantly inhibited. A significant correlation was found between ABCA1 expression and circulating levels of HDL-C. Periodic withdrawals of a high-fat atherogenic diet compared with a regular administration results in a different adaptive response of lipoprotein metabolism, which leads to a significantly higher plasma level of HDL-C and lower TC/HDL-C.

It is now a well established fact that high-level nutrition of the in-lamb ewe during the later stages of pregnancy results in heavy lambs of high vitality at birth and in good milking ewes. On the other hand, when ewes are poorly fed during the same period, or suffer a check, they produce underweight lambs of low vitality and have poor milk yields. While it is agreed that underweight lambs are undesirable, one is often asked whether the larger and sturdier lambs at birth maintain their superiority in later life, a problem on which relatively few results have been published. A study has therefore been made of a large number of birth and weaning weights collected as a normal routine at the Rowett Institute during the past few years.

Histological examination of the rumen wall in intensively managed beef cattle confirmed the superficial nature of many of the lesions present and failed to reveal evidence of secondary bacterial infection. Of the lesions described, only intra-mucosal abscesses and their subsequent erosions proved to be significantly related to the occurrence of hyperkeratosis of the rumen mucosa. The remaining lesions, vacuolation of the stratum granulosum, acute microscopic ulceration, congestion of the submucosa and the presence of leucocyte aggregations in the submucosa, were all independent of this hyperkeratosis.

Eighty-two Scottish Blackface castrated male sheep were used to test whether, from weaning to near maturity, the gigot grew exactly proportionally to the half carcass and whether the tissue in the gigot grew at the same rate as the respective tissue of the half carcass.

While slight deviations from exact proportionality of growth occurred, none could be adjudged significant or important. If the gigot does not grow directly proportionally to the half carcass the data suggested that the gigot tended to grow slightly more slowly than the total half carcass over this period. If gigot muscle does not grow proportional to the total muscle the data suggested that gigot muscle might grow slightly more slowly. If growth of bone tissue is not directly proportional between the gigot and the half carcass the tendency was for the gigot bone to grow slightly faster than total bone while the fatty tissue of the gigot showed a slight tendency to grow more slowly than the half carcass fatty tissue.

Four central performance tests of growth in Hereford bulls from about 10 to 19 months of age on pasture were conducted in New Zealand. From the 100 bulls performance tested 63 were representatively sampled, including bulls with high and low performance test rankings, and progeny tested in dairy herds. Crossbred progeny were purchased from the dairy herds at 3 to 4 months of age, assembled in one location and reared together on pasture for 14 to 15 months prior to slaughter. Regressions of progeny growth and carcass traits on a number of different performance traits for growth of their sires were in almost all cases not statistically significant. The effective heritability, from offspring-sire regression, was 0·07 (s.e. 0·05) for final live weight and 009 (s.e. 0·06) for post weaning gain from about 200 to 550 days of age. It is concluded that central performance tests, as presently conducted in New Zealand, are of limited value for ranking breeding values of bulls for growth. Possible reasons for these results are discussed. It is suggested that pre-test environmental effects and age at the start of the central test are critical factors.

A total of 96 Large White weaner pigs, comprising equal numbers of entire males and females, and of controls and eighth generation index-selected genotypes, were fed ad libitum until 40 kg live weight. From 40 kg until slaughter at 85 kg live weight pigs within genotype and sex groups were fed either ad libitum or 2·2 times maintenance. The left sides of the carcasses were divided into shoulder, middle and ham portions and the middles further divided into eye, wedge and belly dorso-ventral portions. Tissue dissection was performed on all portions separately.

Selected pigs yielded proportionately 0·15 less fat, 0·08 more muscle, a smaller muscle: bone ratio and 4·05 mm less P2 backfat depth than the controls. When the data were adjusted to the same mean P2 fat depth, the carcasses of selected pigs had 0·07 less fat and 0·03 more muscle. There were no appreciable differences between the genotypes in cranio-caudal tissue distribution. However, there were differences in dorso-ventral tissue distribution since the middles of selected pigs had proportionately and absolutely more of each tissue in the belly. There was no evidence that selection against fat at the P2 site had caused any increase in fat lateral to the m. longissimus.

Food restriction increased carcass muscle by 0·10 and decreased fat by 0·17, but had no effect on muscle: bone ratio or cranio-caudal or dorso-ventral tissue distribution. At the same carcass side weight and P2 fat depth, restricted feeding decreased fat by 0·10 and increased muscle by 0·06 in the carcass side.

It is concluded that carcasses of the selected pigs would be undervalued relative to the controls due to less fat and more muscle at the same weight and P2 fat depth. Also, restriction on food intake can cause carcasses to be undervalued relative to feeding ad libitum.

An experiment was undertaken to compare the productivity of crossbred ewes, produced by crossing Texel sires with Rouge de l’Ouest (Rouge) dams and Rouge sires with Texel dams, relative to purebred Texel and Rouge ewes. The purebred and crossbred ewes were crossed with Rouge and Texel sires. The proportion of productive ewes was similar in the purebred and crossbred ewes with an average figure of 0·92. Irrespective of crossing sire, Rouge ewes produced 0·48 more lambs per ewe lambed than Texel ewes (P < 0·001). The two crossbred ewe types (Texel ✕ Rouge and Rouge ✕ Texel) each produced similar numbers of lambs (on average 1·92 lambs per ewe lambed). Individual heterosis values for ewe fertility and prolificacy were small and not significant (–1·67 for the proportion of productive ewes and –3·14 for the number of lambs born per ewe lambed). Maternal heterosis values were also not significant but were of larger magnitude (6·26 for ewe fertility and 3·12 for prolificacy). Lamb mortality (number of lambs born dead per ewe lambed) at birth was similar for purebred Rouge (0·44) and Texel (0·30) ewes and was significantly reduced by crossbred matings and mating the crossbred ewes (individual heterosis –30·68, P < 0·10; maternal heterosis –80·23, P < 0·001). Individual and maternal heterosis values for lamb growth rate from birth to six weeks were 8 (P < 0·05) and 4 (P > 0·05) respectively. Lamb growth rate from birth to weaning was significantly lower in lambs from Texel ewes compared with those from the other genotypes (P < 0·05). Individual and maternal heterosis values for live-weight gain from birth to weaning were 5 (P < 0·10) and 5 (P < 0·01). The results of the current study demonstrate the superior performance of purebred Rouge ewes compared with purebred Texel ewes in terms of prolificacy and lamb growth rate from birth to weaning. However, both breeds had high lamb mortality at birth. Crossbreeding led to the production of hybrid ewes which had relatively high prolificacy with low levels of dystocia and lamb mortality.

Optimum selection directions for average ad libitum food intake capacity (FIC) in growing pigs were derived by means of a biological growth model based on the linear/plateau relationship between protein deposition and food intake. Breeding goal traits were minimum fat to protein deposition ratio (R), maximum protein deposition rate (Pdmax) and FIC. The selection index included FIC, daily weight gain (DG), backfat thickness and proportion of lean meat in the carcass of a full-sib.

Selection indexes were developed for three alternative levels of FIC. If FIC was too low to realize Pdmax, the economic weight of FIC was positive and optimal selection emphasis should be mainly on FIC, resulting in a rapid increase of DG. If FIC was higher than necessary to realize Pdmax, the economic weight of FIC was negative, and short-term selection resulted in increase of carcass leanness but decrease of FIC and DG. If FIC was just sufficient to realize Pdmax, selection should be for R and Pdmax. In this third alternative, the gain in FIC should follow the gain in R and Pdmax in an optimal way and selection should best be carried out with a desired gains index, which results in improvement of DG and carcass leanness.

It was shown that, in cases where FIC was higher than necessary to realize Pdmax, selection with a desired gainsindex should be preferred because this was more profitable in the long term. From the model calculations, it followed that future profit from selection of growing pigs for production traits is likely to decline because of the necessity to increase FIC.

The stage of ossification of various, normally visible, bones were examined by two independent observers on 134 sides of beef from cattle of known dates of birth. These examinations failed to produce sufficiently consistent values to allow the ages of these cattle at slaughter to be determined from their skeletal characteristics within an accuracy of 3 months.

Three methods were used to make differential counts of living and dead bull spermatozoa in samples of frozen semen in an egg-yolk citrate medium containing glycerol.

With two methods (‘phase’ and ‘nigrosin’ methods) dead spermatozoa were identified by their altered structure. With a third method (nigrosineosin) dead spermatozoa were identified by their staining affinity. With the phase method spermatozoa were immobilised by treatment with approximately M/40 sodium fluoride and were examined by phase-contrast microscopy in unfixed wet preparations. With the other two methods the spermatozoa were examined in smears stained either with nigrosin alone (nigrosin method) or with nigrosin and eosin (nigrosin-eosin method).

Analysis of variance of the results of a factorial experiment involving fluoride-treated and untreated samples from 6 bulls with the three methods showed that differences between semen samples contributed 66% of the variation. A defect of the phase method was that the variance between counts was greater than the theoretically expected value.

All spermatozoa in nigrosin-eosin stained preparations were stained with eosin within a few days of the smears being made, so that living and dead spermatozoa could not be distinguished by their differing affinities for eosin. Repeat counts on nigrosin-stained preparations did not differ significantly from counts made several days previously. Sodium fluoride in the concentration used here (M/40) tended to reduce the percentage of dead spermatozoa.

A series of trials were designed to determine the slaughter weight of cutting pigs at which lean meat production is most economical, and to investigate nutritional factors which affect lean meat onput in cutting pigs of about 260 lb. live-weight. The trials involved about 1100 pigs and ad lib. feeding was adopted from weaning to slaughter.

In the first trial, pigs were fed on various diets to 300 lb. live-weight. The diets differed in the amount of protein fed during the 90–180 lb. growth period, and the most economic growth was made by feeding a high protein (17 %) diet to 140 lb., or a medium protein (14 %) diet to 180 lb. followed by a cereal-mineral diet thereafter to 300 lb.

Animals were slaughtered and dissected at various live-weights between 90 and 300 lb. and it was found that killing-our percentage, the percentages of usable meat (lean plus fat) and of fat, increased with carcass weight. The increase in fat deposition was mainly at the expense of the non-edible parts of the carcass. Onput of lean and increase in area of eye muscle occurred throughout the range.

Total food requirements, expressed as pounds of food, calories of gross energy or pounds of protein, per pound of usable meat produced decreased as slaughter weight increased. The cost of food required to produce a given quantity of lean meat was least when pigs were slaughtered between 240 and 260 lb. when the commercial value of the remainder of the carcass was taken into account.

The second trial investigated the effect of two levels of protein and mineral supplementation of cereals during the 140–260 lb. growth period of heavy pigs. Correct mineral supplementation of cereals was essential because, although lean meat production was not increased, the cost of food required to produce it was less. The lower protein diet had no effect on growth or carcass composition, but the higher protein diet increased the lean meat content of carcasses and decreased the amount of food required to produce it. The production of the extra lean meat, however, was not economical because of the cost of the high protein diet.

The third trial showed that replacement of barley by wheat during the 140–260 lb. growth period led to carcasses having less lean meat and to higher feed requirements. This is probably connected with the high energy content of wheat as compared to barley.

Two experiments are described in which growing lambs were offered ad libitum two concentrate pelleted diets containing 60 (diet C) or 230 (diet D) g/kg barley straw.

In the first experiment, eight male and eight female lambs were used to determine the outflow rate from the rumen of chromium-mordanted fish meal and soya-bean meal, estimated from faecal marker excretion. Diet D promoted a higher rumen outflow rate (0·0769 per h) than diet C (0·0486 per h); no differences were found either between sexes or between Cr-mordanted protein supplements.

In the second experiment, the rumen degradation of fish meal, soya-bean meal, sunflower meal, pea seeds and sweet lupin seeds was studied by incubating the supplements in polyester bags in the rumens of four lambs, following a change-over design. Increasing the proportion of straw to 230 g/kg increased the rate of nitrogen disappearance from all vegetable supplements, the differences being significant only for pea seeds.

When degradation kinetics and outflow rates were considered together, effective nitrogen degradability of protein supplements was reduced by the increased proportion of dietary straw, indicating a greater influence of rumen outflow rate than of the increased rate of microbial degradation.

An experiment was carried out in which a cereal supplement was given to beef cattle, either in suspension in water or as a dry supplement. There were no significant differences between treatments in live-weight gain, food intake or food conversion ratios. Although there was a tendency for the digestibility coefficients of all constituents to be lower on the diet containing the liquid supplement, the differences were not statistically significant. It is concluded that giving a supplement in suspension has no adverse effect on the utilization of the overall diet and could facilitate mechanization of the feeding operation.

A comparison was made of various devices to obtain preantral follicles from bovine ovaries. The most productive collection methods in terms of number of follicles obtained were the tissue chopper and the grinder method, with an average number of 122·25 (s.e. 5·06) and 120·45 (s.e. 6·89) preantral follicles, respectively. These were followed by ficoll gradation (119·90, s.e. 7·95), mincer (101·75, s.e. 3·98), cell dissociation sieve (100·50, s.e. 3·42) and homogenizer (95·75, s.e. 6·38). For enzymatic digestion, more time was needed and the method was less productive. Microdissection could supply good quality (80% live when collected), larger sized follicles (120 to 220 µm) but with the lowest yield (10·65, s.e. 0·94) per ovary. The isolated follicles did not show any difference (P > 0·05) in viability until day 7 of in-vitro culture irrespective of method used to harvest follicles. Accordingly the new grinding device can be recommended as a replacement for the existing mechanical devices as it can yield the same percentage (47%) of live preantral follicles but of a wider diameter range (40 to 180 µm) per ovary.

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.

1. A growth and digestibility trial was carried out with 27 British Friesian calves given diets having either 3·1, 2·8 or 2·4 Meal metabolizable energy per kg dry matter and either the same concentration of protein or the same protein-to-energy ratio.

2. Daily dry-matter intake and rate of gain in live weight increased significantly as the energy concentration of the diet was reduced. There were no significant differences in digestible-energy intake between calves given the different diets, although the trend was the same as for dry-matter intake.

3. Both dry-matter digestibility and energy digestibility were lowest for the low-energy diet.

A total of 64 Border Leicester × Greyface ewes were offered eight diets comprising four levels of digestible crude protein and two levels of metabolizable energy (ME) intake during gestation. After parturition the ewes on each gestation treatment were offered a high or low level of ME intake at a constant level of crude protein intake. Nitrogen balances were carried out on all ewes during weeks three and four of lactation.

Digestibility coefficients and output of nitrogen in the milk measured during the lactation balance periods were not significantly affected by the gestation treatments. Body nitrogen balance during lactation was significantly affected by the level of protein offered during gestation.

Empirical equations relating digestible crude protein intake and ME intake to milk nitrogen production and body nitrogen balance indicated that a digestible crude protein intake of 7·9 g/kg W0·75 per day and a ME intake of 220 kcals/kg W0·75 per day resulted in the production of 0·70 g milk nitrogen per kg W0·75 or approximately 100 g of milk per kg W0·75. The corresponding level of body nitrogen retention was 0·162 g/kg W0·75 per day and showed no consistent trend due to level of protein intake during gestation.