Twelve Ayrshire cows which had reached or just passed peak lactation were selected and divided into two balanced groups. One group was fed strictly according to yield. The other was fed overall according to yield, but was subjected to a 4-day cycle of energy intake. For 2 days energy intake was 12·2% above calculated requirements and for the next 2 days intake was 12·2% below calculated requirements. The treatment was imposed for 10 weeks and milk yield and composition, body weight and blood composition were measured in both groups of cows. A significant variation in daily milk yield and daily solids-not-fat yield was found to follow the feed cycle. Blood composition showed no significant variation.

Synthetic lysine and fat supplements are widely used in diets for growing pigs. However, there is evidence to suggest that free lysine is more rapidly absorbed than protein bound amino acids resulting in reduced growth performance particularly under infrequent feeding regimes. In addition, the incorporation of conventional fat supplements into cereal based diets is problematic particularly where on-farm mixing of feed is carried out. One potential solution to both these problems is to use fat coated synthetic lysine sources which have recently become available and two such materials were evaluated in this study.

Four dietary treatments were compared. These were a control diet (C) with soya bean meal as the protein supplement and diets in which 0.3 of the total lysine was supplied from either synthetic lysine (S) or synthetic lysine coated with a single (SC) or a double layer(DC) of hardened soya oil. All diets were barley based and were formulated to contain the same level of total lysine (0.01) and hardened soya oil.

Results of two fattening trials, with 49 crossbred ram lambs fattened on an all-concentrate diet given ad libitum with toasted soya bean meal as the main protein source, are presented.

In the first 84-day trial (January to March 1979) there were 32 twin- and triplet-born ram lambs of five genotypes, i.e. Finn-Awassi F2 (FAF 2), Romanov-Awassi F2 (RAF2), Assaf × Finn-Mutton Merino (AsFMM), Suffolk × Finn-Awassi (SuFA) and Suffolk × Finn-Mutton Merino (SuFMM). The overall means ( + s.d.) of the parameters investigated were: initial age, 64·6( + 4·5) days; initial weight, 17·6(±3·0)kg; final weight, 52·2(±4-l)kg; daily gain, 411( + 38)g; food intake, 1·5(±0·3)kg dry matter per day; and food conversion, 3·6( + 0·8)kg dry matter per kg gain.

In the second 56-day trial (August to September 1979) there were 17 single-, twin- and triplet-born FAF2 and Assaf × Finn-Awassi (AsFA) ram lambs. The overall means (±s.d. ) of the parameters investigated were: initial age, 64·1(±8·7) days; initial weight, 24·3(+ 3·6)kg; final weight, 48·5(±5·6)kg; daily gain, 431(±24)g; food intake, l-5(±0·3)kg dry matter per day; and food conversion, 3·5( + 0·7)kg dry matter per kg gain.

In both trials the differences between genotypes in daily gain, food intake and food conversion were not statistically significant and the performance of the progeny of Australian Suffolk and Assaf rams was similar to that of the progeny sired by Finn-Awassi and Romanov-Awassi rams.

Food intake and food conversion were highly correlated with weight of lambs, i.e. r = 0·8864 and r = 0·8857 (d.f. 36), respectively.

In both trials the relationships between daily gain and the pre-fattening performance of the lambs (birth weight, type of birth, weaning age and weight, rates of growth to weaning and from weaning to the start of the trials, as well as the initial age and weight) were not statistically significant.

The fattening process of male cattle was divided into three weight stages: 150 to 250kg, 250 to 400kg, 400 to 490kg. Seventy animals were fed either a control (C) diet containing 10·3 MJ/kg metabolizable energy and some hay, or an experimental (E) diet containing 8 4 MJ/kg, in which NaOH-treated wheat straw (450g/kg) and long straw (50 g/kg) were incorporated.

The diets were given during the three weight stages to five treatment groups as follows: 1. C-C-C. 2. E-E-E. 3. C-E-E, 4. C-E-C, and 5. E-E-C. The average daily gain and metabolizable energy conversion ratios were: 1344, 980, 1127, 1145, 1094g/day and 71·4, 90·6, 77·3, 73·7, 79·8 MJ/kg live weight, respectively. The saving of concentrates plus hay in groups 2 to 5 compared with group 1 was 1·33, 1·65, 0·84 and 0·91 kg/kg live weight respectively, and the concentrates plus hay by straw replacement ratio was 3·80, 2·12, 2·00 and 3·06, respectively. Dressing percentage and percentage of fat in the large depots of the animals in groups 1 to 5 were 57·2, 58·7, 58·3, 57·8, 57·9 and 3·88, 2·28, 2·52, 3·42, 2·81, respectively. The results suggest that it is not economical to feed the E-diet to animals before they reach a weight of 250 kg, and that termination of the feeding process by a highly concentrated diet is not advantageous.

The East Friesland breed, developed as a dairy sheep, has a potentially useful role as a sire of first-cross breeding ewes from hill breeds of sheep. Advantages have been shown in terms of reproductive and lactation performance (Doney et al, 1983, Gunn, 1986) but the carcase conformation may reduce the acceptability of first-cross castrated male (wether) lambs. The characteristics of lambs derived from dairy-type breeds may be suitable for the heavy, lean carcase market (Butler-Hogg et al, 1985). The present study was undertaken as a pilot investigation of the potential growth rate and carcase composition of wether lambs over a range of live weights. East Friesland X Blackface (EFB) wethers were compared with a similar group of Border Leicester X Blackface (BLB) and a smaller group of East Friesland X North Country Cheviot (EFC) wethers.

The performance of crossbred progeny of Oxford, Texel, Texel-Oxford, Charollais, Charmoise and Meatlinc terminal sires, mated with crossbred ewes, were compared.

The comparisons took place at ABRO's lowland farm in Staffordshire from 1979–1981. The crossbred ewes were by various crossing sire breeds out of a Scottish Blackface stock. Three or four six month old rams of each breed were used in each year, but 9 Texel-Oxford rams were used in 1979 and 1980. Oxford rams were used only in 1981.

A preliminary study was conducted to quantify the lipid produced by differentiated 3T3-L1 cells after incubation in Dulbecco’s Modified Eagle Medium (DMEM) containing 10% foetal bovine serum (FBS), supplemented with or without dimethyl-sulphoxide (DMSO; 9•6 g/l) and acetone (1•2 g/l). The two media treatments were applied to 3T3-L1 cells, plated at either 15K or 30K cells per well in 24-well plates. Cells were grown to confluence (96 h) and then treated with dexamethasone, methyl-isobutylxanthine and insulin for 48 h and later maintained in their respective media treatments for another 144 h. Cells from each treatment were recovered after two, 5-min incubations with trypsin, washed and resuspended in DMEM and counted on a haemocytometer. The lipid in the cells was extracted with hexane derivatized with tetramethyl-guanidine and analysed by gas chromatography. Final mean cell density was 6•8 (s.e. 0•18) ✕ 105 and 4•6 (s.e. 0•19) ✕ 105 when initially plated at 30K and 15K cells per well, respectively. Inclusion of DMSO and acetone in the medium did not affect final cell numbers. Plating density did not affect concentration of lipid (0•55 (s.e. 0•08) mg per 1 ✕ 105 cells) but inclusion of DMSO and acetone led to overall decreases in total lipid concentration. Results indicate that initial plating density influenced final cell number in treatment cultures, but that DMSO and acetone treatments only had an effect on final lipid concentration. Collectively, these data suggest that the application of treatments to cell cultures may be influenced by the carrier vehicle that the treatment is contained in and this should be considered when developing an in vitro system to evaluate growth and development of adipocytes.

The effects on herbage intake of changes of herbage mass associated with different stocking rates were studied in Greyface (Border Leicester × Scottish Blackface) ewes in the autumn. Intake was measured in 5-day periods in late September (PI), late October (P2) and late November (P3) on two established, perennial ryegrass/white clover swards (SI and S2). Both swards had previously been variably stocked to produce areas with a range in herbage masses, some of which were grazed continuously (G) at stocking rates declining from 18 to 6 ewes per ha.

Intake was also measured in P2 and P3 on other areas of the swards which were ungrazed for 6 weeks in September and October (C) and then stocked at 18 ewes per ha. Intakes of dry matter, organic matter and digestible organic matter were 16 g, 10 g and 7·5 g/kg live weight, respectively. Organic matter digestibility was 075 in PI and P2 but declined in P3.

Differences in herbage intake and digestibility arose largely because of differences between the swards in herbage mass, sward height and sward density. Ewes in condition scores > 3·00 in early September had lower intakes at all times than did thinner ewes. Changes in sward management associated with different strategies of use had little long-term effect on herbage intake. Keywords: digestibility, herbage, sheep, stocking rate.

The rumen in situ technique has been adopted as the standard method (AFRC, 1992) for the characterisation of nitrogen in feedstuffs for ruminants. Differences in the degradation characteristics of identical samples both within and between laboratories have been observed (Madsen and Hvelplund, 1985; Oldham, 1987; Kandylis and Nikokyris, 1991). These variations may relate to a number of variables including, cloth type, weave, pore size, sample preparation, basal diet of host and post-incubation washing procedure. Another of the possible causes of variation between similar measurements may be dynamic changes in rumen metabolism. Wilson and Briggs (1955) observed that the day-to-day variation in viable bacterial counts in animals fed a fixed diet was even greater than those observed with gross changes in basal diet. The aim of the present experiment was to observe the day-to-day variation in the rumen of sheep fed a constant diet over 18 weeks.

Proteins which escape digestion and absorption in the small intestine of the pig are extensively metabolized by the microbial flora of the large intestine. It is known that bacterial enzymes are potentially capable of catabolizing all amino acids (Michel, 1966). Furthermore, it has been shown that virtually all soluble protein or amino acids introduced into the caecum are rapidly metabolized, absorbed (presumably as ammonia, amines etc.) and the nitrogen (N) derived from them is rapidly excreted as urea (Zebrowska, 1973). This has led to the general recognition that the amino acid composition is not a reliable measure of undigested dietary amino acids in pigs. It has been estimated that only 6% of faecal N is of undigested dietary origin, while the remainder is of bacterial or endogenous origin (Low, Sambrook & Yoshimoto, 1978). It was therefore of interest to estimate which proportions of faecal N derived from a barley-soya diet, are of either bacterial, endogenous or undigested dietary origin. We have used germ-free or conventional miniature pigs for this work because they are small enough to be kept in our isolators for periods of up to 20 weeks. It is emphasised that this is a preliminary report on our first efforts at raising miniature pigs under germ-free conditions.

In a multibreed experiment 306 females from 25 British breeds of cattle were given a standard pelleted diet ad libitum. Correlations of food conversion efficiency (FCE) with body weight, weight gain, and food intake were studied over 12-week and longer periods from 12 to 72 weeks of age. Inter-age correlations of FCE with itself and the other traits were also studied over age intervals separated by 12, 24, 36 and 48 weeks. The between-breed correlations were genetic while the within-breed correlations were phenotypic.

Between breeds, FCE measured over the full age range from 12 to 72 weeks appeared to be very highly correlated with FCE measured over the 12-week period between 24 and 36 weeks of age. Correlations of 12 to 72 week FCE with traits not requiring measurement of food intake were much lower, being at most 0·77 for weight gain, 0·73 for weight gain per unit body weight and 0·57 for body weight. The pattern of correlations implied that over constant age ranges the larger faster-growing breeds with high intakes tended to be more efficient; however, these correlations were generated primarily at early ages between 12 and 36 weeks and FCE at later ages could not be predicted from other traits measured at earlier ages. Nevertheless, between-breed selection to improve FCE by indirect selection on body weight and weight gain could be effective but there would appear to be no advantage in waiting beyond 1 year of age.

Within breeds, correlations of 12 to 72 week FCE with FCE measured over 12-week periods increased with age from 0·24 to 0·61. Correlations of FCE with weight gain in the same 12-week periods were quite high (0·49 to 0·89) and those with weight gain per unit weight were invaribly higher (0·68 to 0·90). However, as a predictor of FCE in any subsequent period, weight gain per unit body weight was poor and weight gain of no value whatsoever. There was no strong association of FCE with body weight.

Primary growths of perennial ryegrass and red clover were ensiled with formic acid (2 1/t fresh crop), o an equal quantity of formic acid together with formaldehyde (46 or 49 g/kg crude protein in the ryegrass or red clover respectively). The four silages were offered ad libitum to 12 groups, each of five British Friesian steer calves, either alone or with urea or maize starch supplements at 18·4 or 185·2 g/kg total dry-matter intake respectively.

Digestible organic matter and digestible energy intake, live-weight gain, carcass weight, nitrogen retention and all digestibility measurements were higher on the ryegrass silages than on the red clover silages. However, dry-matter intake was higher on the red clover silages.

Formaldehyde treatment reduced lactic and total acid content, and protein degradation in the silages. It also increased intake, live-weight gain and nitrogen retention on ryegrass but not on red clover, the effect being greater when the urea supplement was given. Digestibility measurements were depressed by formaldehyde treatment, although cellulose digestibility was only depressed in the ryegrass silage.

Supplementation with starch depressed silage intake and nitrogen and cellulose digestibility, but increased dry matter, organic matter and energy digestibilities, digestible organic matter and digestible energy intakes, live-weight gain and carcass weight. The positive intake, live-weight gain and carcass weight responses were greater on the silages treated with formic acid, while the digestibility and the live-weight gain responses were greater on the red clover silages. Starch supplementation did not improve nitrogen retention.

The different animal production responses to formaldehyde treatment on the ryegrass and red clover silages are discussed.

Silage effluent represents a potential pollutant and a loss of ensiled nutrients. An absorbent provides the possibility of absorbing effluent, aiding fermentation and increasing the feeding value of the silage. Sugar beet pulp (SBP) nuts and rolled barley (RB) were evaluated as absorbents with direct cut grass silage.

Perennial ryegrass swards of 222 g/kg average dry matter were direct cut between 10 and 12 July 1989. Grass was ensiled with the following rates of absorbent per tonne of fresh material:

1. 1. 20 kg SBP (S20).

2. 2. 40 kg SBP (S40).

3. 3. 40 kg RB (B40).

4. 4. Untreated (U).

Production of silage effluent was measured with a tippler mechanism attached to an electronic logger and recorded daily until 22 September. The silages were individually fed through Calan Broadbent doors to 48 x 12 month old Friesian steers between 24 October and 19 December.

The widespread use of artificial insemination (AI) in the United Kingdom sheep industry has been limited by the poor conception rates obtained after cervical insemination of frozen-thawed semen. The major problem in this respect is the impairment of sperm transport through the cervix, particularly when AI is used in conjunction with oestrus synchronisation.

Previous studies (Killeen and Caffery, 1982; Maxwell, 1984) have indicated that a laparo-scopic technique for intrauterine insemination in ewes may overcome such limitations. At the moment, however, sufficient data on the optimum time of insemination and sperm doses required to maximise fertility in British breeds are not available. The present study was conducted to establish the optimum time of intrauterine insemination using frozen-thawed semen.

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.

The accuracy of progeny testing for a continuous trait when the auxiliary information was based on ‘all-or-none’ type of traits with a multi-factorial threshold model was examined. The accuracy of the progeny test was found always to increase with the inclusion of the auxiliary trait. It followed the same pattern as in the case of continuous auxiliary trait. However, there was an additional feature in that the accuracy was also dependent on the probability of incidence of the discrete trait unless either the progeny group size was very large, and/or there was no genetic correlation or else the probability of incidence was itself extremely low. Compared with the case when the auxiliary trait was continuous, there was a loss in accuracy which can be looked upon in two ways. First, the continuous auxiliary trait is itself made ‘all-or-none’ type by a threshold and the accuracies compared in the two cases. The loss increases symmetrically in either direction with increase in positive or negative directions of the difference in genotypic and phenotypic correlations. Secondly, a comparison can be made of the accuracy when the auxiliary trait is normally distributed with that when it is binomially distributed but with the same amount of genetic information on the observed scale as given by the heritabilities and genetic correlations. No loss now occurs if the two classes of the binomial trait are equally likely and the loss in accuracy increases with the decrease in the standard deviation of the binomial distribution for given values of other parameters. It was found also that the use of binomial auxiliary trait reduced the number of progeny required to attain a pre-assigned level of accuracy, resulting in a decreased cost of the programme compared with that when no binomial auxiliary trait was used.

During a survey of beef production in East Anglia carcasses of 163 Friesian, 87 Dairy Shorthorn and 45 Aberdeen-Angus × Friesian steers and 44 Aberdeen-Angus × Friesian heifers were measured and scored by visual assessment for fat development. They were also graded by the Ministry of Agriculture, Fisheries and Food.

Age data indicated that the Friesian steers were, on average, younger at slaughter than the other groups, but they were incomplete and comparison was based on carcasses of the same weight. The Dairy Shorthorn steers had higher mean values than Friesians in three of the carcass measurements taken. The Dairy Shorthorns had a higher average fatness score and a higher proportion of Grade A carcasses. Aberdeen-Angus × Friesian steers had lower mean values for measurements of the hind leg, higher fatness scores and a higher proportion of Grade A carcasses than either of the two pure breeds. Aberdeen-Angus × Friesian heifers had lower mean values for measurements of both fore and hind legs, higher fatness scores and a slightly higher proportion of Grade A carcasses than the steers.

The information gained by use of measurements and fatness scores explained, but did not materially add to, the assessment of the relative value of the groups of carcasses given by grade.

Smith (1986) identified the theoretical potential of multiple ovulation and embryo transfer (MOET) to increase the rate of genetic improvement within nucleus sheep breeding flocks by upto 100%. The likely genetic benefits of MOET arise from the potential to overcome limits to female reproduction thus allowing increased selection intensity and reduced generation intervals among females. The present study was conducted to evaluate the potential for MOET from 18 month-old maiden ewes (gimmers) in comparison with aged donor ewes.

In October 1991, a group of twenty 18-month old ewes and twenty aged ewes (3.5 year-old) were synchronised into oestrus using intravaginal pessaries containing 45 mg Cronolone (Chronogest, Intervet Laboratories Ltd.) inserted for 12 days. Superovulation was achieved using 20 i.u. of ovine follicle stimulating hormone (Ovagen, Immuno-Chemical Products N.Z. Ltd) given in eight equal doses at 12-hourly intervals starting 58 hours before progestagen pessary withdrawal.

Identical group-feeding experiments (each of 90 days duration) were conducted in the summer and in the winter of 1968. The purpose was to study the feed-lot performance of the Grey Shirazi breed on high- and low-concentrate diets with or without diethylstilboestrol (DES) in two different seasons of the year. Lambs on the high-concentrate diet gained more than those on the low-concentrate diet both in summer and in winter. On both diets lambs performed better under cold than under warm conditions. There was no difference when DES was given orally with the above two rations.

Lamb producers in the Less Favoured Areas (LFAs) of the European Community appear, for different reasons, to be constrained by the economic value of the indigenous small-sized sheep breeds. The trial reported here forms part of a collaborative project whose overall aim is to improve the quality and marketability of sheep meat produced in the LFAs. The objective of this trial was to assess the growth potential of nine small sized sheep breeds, across three centres, providing a basis for subsequent production work. The three collaborating centres in Greece (paper no. 112), Spain (paper no. 26) and Scotland used indigenous breeds appropriate to their LFAs. The three British breeds studied were Scottish Blackface (SB), Welsh Mountain (WM), and Shetland (SH).