The changes in muscle protein and plasma radioactivity with time have been observed in anaesthetized pigs receiving constant infusions of [14C]glycine and [3H]tyrosine. The specific radioactivity of muscle protein was found to increase linearly with time. However, it was not possible to calculate absolute rates of muscle protein synthesis for the plasma radioactivity had not reached a plateau after 8 h infusion.

The specific radioactivities of Pietrain muscle protein increased more rapidly than those of Large Whites when animals of the same lean mass, receiving the same dietary amino acid supply per unit of lean mass, were compared. However, when considered with respect to published biochemical data, these results support the hypothesis that the differences arise from inequalities in plasma specific radioactivities; which appeared to be related to differences in blood volumes, between pigs of the two breeds, at the same age. When plasma specific radioactivity/time relationships were adjusted so as to account for this variation no significant differences were found, indicating that muscle protein synthesis and muscle growth proceed at similar rates in the two breeds.

A 2 × 3 factorial trial designed to investigate the effects of castration and three diets on growth and body composition of 30 male Dorset Horn × (Border Leicester × Merino) lambs is described. The three diets were: (a) a standard ration of equal weights of lucerne chaff and pelleted concentrates; (b) a similar ration to (a) plus 7·5% by weight of lipid (peanut oil and tallow); (c) a greater ration of (a) calculated to be isocaloric for digestible energy with diet (b).

At the beginning of the trial a group of 40 lambs (20 rams, 20 wethers) were shorn and five rams and five wethers were selected at random and slaughtered to establish initial body composition. The remaining 30 lambs, 15 rams and 15 wethers aged about 22 weeks and having mean weights of 33·0 kg (rams) and 31·2 kg (wethers), were randomly divided within sex into three groups and allocated to the three diets for 92 days. At the end of this period the lambs were again shorn, and then slaughtered and dressed.

During the trial, rams gained significantly (P < 0·001) more weight than wethers, and lambs on diet (a) gained significantly (P < 0·01) less weight than those on (b) and (c). Weight gains on the latter two diets were similar. Diet generally had little effect on body composition, although there was a tendency, within sexes, for lambs on diet (b) to have a greater fat content than those on the other diets. Rams had significantly greater carcass weights (P < 0·01), head percentage (P < 0·001) and various m. longissimus dorsi dimensions than wethers, but significantly less fat in all the locations measured, including a lower percentage of chemically extractible fat in the offals and carcasses. Estimations of the energy stored in the wool-free body during the trial indicated that wethers stored significantly more energy in the form of fat than rams (P < 0·001), but that rams stored significantly more non-fat energy than wethers (P < 0·001). It is concluded that a maximum growth rate exists for the non-fat body, and that it is higher in rams than wethers. Thus the addition of dietary lipid (which increases energy intake with comparatively small increases in weight or volume of feed), is more likely to promote fat deposition in wethers, which have a lower maximum capacity for non-fat storage, than in rams.

Merino wether lambs and yearling sheep grazed irrigated lucerne or grass pastures in the period immediately before slaughter. Some of the sheep grazed continuously on the lucerne or grass for up to 6 months, while others grazed grass and then lucerne in the 4 weeks immediately before slaughter, over this same period. A laboratory taste panel compared the flavour of the meat from the grass and lucerne-fed sheep.

The intensity of the flavour characteristic of cooked meat from lucerne-fed lambs or sheep was found to increase in intensity with increasing length of time of grazing the legume. In addition, both 4-week and continuous-lucerne grazing treatments exhibited significant seasonal effects, in which the intensity of the lucerne-derived taint was found to vary throughout the year, with a maximum intensity appearing when lucerne was grazed in the cooler months.

A study was conducted to compare field crops and varieties grown at the Kufra Agricultural Project, Libya, and the Imperial Valley Field Station, El Centro, California. Lucerne (Medicago sativa L.), barley (Hordeum vulgare L.), wheat (Triticum octivum L.), sudangrass (Sorghum bicolor Moench) were grown at both locations in 1969–70.

Yield studies at Kufra, Libya, and the Imperial Valley Field Station indicated that the crop performances were equally well adapted at both locations. Lucerne yields were higher at Kufra, which may have been due to more moderate temperatures and less salt in soil and water at Kufra. Low yields in some of the other crops at Kufra such as wheat may be due to inexperience and inadequate fertilizers. Newly developed varieties for Imperial Valley should be adapted to the Kufra area.

In view of the dependence of fat metabolism on the size of fat cells and the lack of information describing the change in fat cell size which occurs during growth in pigs, an examination was made of the size of subcutaneous fat cells in Pietrain and Large White pigs of 30–95 kg live weight. A microscopic procedure was used and fat cell diameter was measured at two levels in the outer layer of shoulder fat and at two levels in the inner layer.

In both breeds the rate at which cell diameter increased in size with live weight was greater in the inner layer than the outer layer. At all levels this rate of increase was greater in Pietrains. At the two levels in the inner layer the cells from Pietrains increased in size by 41% and 54% between 30 and 95 kg live weight and the cells from Large Whites increased in size by 23% and 36%. The result was that at 95 kg live weight both breeds had cells of similar size in the inner layer.

Therefore in pigs of the same live weight, cell size varies, depending on the site at which the examination is made and the breed of pig. Even at constant cell size, however, the lipogenic capacity of the fat from different levels and different breeds must be different since the cells increase in size at different rates.

The effects of starvation, glucocorticoid administration, and the feeding of an all-concentrate diet, on the 14CO2-fixing activities of pyruvate carboxylase (EC. 6.4.1.1), phosphopyruvate carboxylase (EC. 4.1.1.32) and propiony1-CoA carboxylase (EC. 6.4.1.3) were measured in liver from lactating cows. Starvation caused a 26% decrease in propiony1-CoA carboxylase activity, glucocorticoid administration a 35% decrease in phosphopyruvate carboxylase activity, and the all-concentrate diet 24 and 41% increases in the activities of phosphopyruvate carboxylase and propiony1-CoA carboxylase respectively.

The actual transpiration of Mexipak wheat (Triticum aestivium L.) was determined by the inflow-outflow method and by soil moisture determination by the use of a neutron probe and gravimetrically. Three irrigation treatments were used during the 1969 season, wet, medium and dry. Amounts of water given were 370, 310 and 255 mm for wet, medium and dry treatments respectively. One irrigation treatment was used during the 1971 and 1972 seasons in which 620 and 700 mm of water respectively was given. However, during the 1973 season, two wet irrigation treatments of 560 and 670 mm of water were used. Values of Et measured by different methods were closely related. Seasonal averages of Et were 2·55, 1·99 and 1·62 mm/day for wet, medium and dry treatments respectively. The empirical coefficient (f = Et/Eo) under wet treatment, was found to be higher than that given by Penman (1956) for short grasses and higher than that obtained by Boumans et al. (1963) for wheat and barley in Iraq. The empirical coefficient Kb in the Blaney-Criddle formula was less than the value given by Blaney & Criddle (1950) for an arid climate and less than the value obtained by Boumans et al. (1963) for wheat in Iraq. The water use efficiency for grain production was greater under dry than under wet treatment.

Seeds of wild safflower, Carthamus oxyacantha Bieb., collected from the Bajgah area, Iran, were subjected to chilling and/or scarification and their germination and emergence characteristics and seedling growth were studied in two laboratory experiments. Seeds of Arak 2811 variety of cultivated safflower, C. tinctorius L., harvested from the same area at the same time was used for comparison.

In the first experiment, the untreated, scarified, chilled at 0 °C for 1 month, and chilled and scarified wild seed and seed of the variety Arak 2811 were incubated at six different temperatures (5, 10, 15, 20, 25 and 30 °C) and their germination percentage and seedling lengths were recorded. In the second experiment, the seeds of the above five treatments were planted in a silty clay loam at room temperature (23 ± 2 °C) and their emergence and seedling heights were noted.

In all cases, the cultivated variety, Arak 2811, had higher germination and emergence percentages and seedling heights than the wild type. Germination of both strains was greatly reduced at the two extreme temperatures (5 and 30 °C). The optimum temperatures for germination of the wild and the cultivated strains were between 15 and 20 °C.

Scarification of the wild seed did not improve the germination or emergence percentages and chilling of the seed for a month at 0 °C reduced the emergence of the wild seed. Temperature of germination, however, seemed to be an important factor affecting germination and seedling growth of wild safflower.

Of a group of 24 pregnant Scottish Blackface sheep 12 were killed at the outset and the remainder offered, ad libitum, a poor quality hay. At the end of pregnancy seven more were killed and the remainder offered, during lactation, 3 kg/head/day of a semipurified diet of 64% dry-matter (D.M.) digestibility, and containing 18% crude protein (CP), 1·17% Ca and 0·82% P in the D.M. Milk production was determined at weekly intervals and milk samples obtained at these times for estimation of Ca and P concentrations. These sheep were killed 42 days post-partum. The shorn empty bodies were analysed for fat, protein, Ca and P contents.

The feeding of the poor quality hay caused losses of 76, 37, 15 and 15% of the body contents of fat, protein, Ca and P, respectively, during pregnancy. Despite maintaining a moderate milk yield (1·5 kg/day) the ewes were in positive Ca and P balance during early lactation and had restored the skeleton to its initial mineral content by 42 days post-partum. The rate of absorption of Ca was calculated to have been at least 115 mg/ kg body weight (BW) which is double other estimates in the literature for sheep at this stage of lactation.

These differences are discussed in relation to mechanisms for adaptation of Ca metabolism which have been proposed for other species.

To test the hypothesis that the ingestion of Mo-rich soils by ruminants might adversely affect Cu metabolism, four groups of initially hypocupraemic ewes were repleted with a Cu-supplemented diet either soil-free or containing 10% of one of three soils of low, medium and high Mo content. The three soils were equally effective in inhibiting the response in plasma Cu and probably reduced the availability of Cu by more than 50%. The ingestion of certain soils produced increases in urinary Mo and Zn concentrations, indicating that the Mo and Zn ingested in soil can be biologically available: however, these Cu antagonists were probably released in insufficient quantities to have contributed greatly to the observed interference with Cu metabolism. Soil ingestion may be involved in the aetiology of hypocuprosis in cattle and swayback in sheep, since it commonly constitutes 10% of the D.M. intake of animals grazing winter pasture.

64Cu and an indigestible 103Ru-labelled marker were administered into the alimentary tract of six artificially reared lambs on four occasions, 28 and 14 days before weaning and 15 and 42 days after weaning. The ratio of 64Cu: 103Ru excreted in the faeces was used to measure the apparent availability of Cu.

Mean Cu availability decreased from 71·0 ± 3·7 to 47·2 ± 7·8% immediately before weaning and to 10·8 ± 1·4% 15 days after weaning.

The relationship between availability (y, %) and age (x, days) prior to weaning was described by the equation

When half of the lambs were given abomasal doses of 64Cu + 103Ru 42 days after weaning, the mean Cu availability was 21·4±4·0% compared with 3·7±2·1% for those dosed via the rumen.

64Cu present in the whole plasma volume 20 h after dosing (y, % dose) was highly correlated with availability (x, %), the equation being

Four out of a group of eight milk-fed lambs were given access to a proprietary concentrate from birth and milk intake was progressively restricted so that by 15–21 days they were wholly dependent on the concentrate. Mean Cu availability at 23 days was 8·3±3·4% compared with 75·0±5·4% for lambs continuing to receive milk substitute alone. The corresponding values for 64Cu in plasma were 0·34±0·03 and 1·41±0·14% dose.

Less than 1·1% of the 103Ru and 64Cu doses were excreted in the urine after 48 h and no 103Ru was detected in the plasma.

The nutritional significance of and mechanisms for the reductions in Cu availability with age and weaning are discussed and methods for measuring Cu availability compared.

Observations were made over a period of 3 years on a total of 331 Nungua Black Head and 104 West African Dwarf sheep. It was shown that ewes of these breeds responded strongly to stimulation occasioned by the sudden introduction of rams which had been separated from them for 10 months. Sudden ram presence apparently altered the normal oestrous cycle of a substantial number of ewes which unlike temperate breeds showed behavioural oestrus soon after being run with the rams resulting in about a quarter of the flock being bred on the first day of association with the ram. This behavioural oestrus must have been accompanied by ovulation as shown by the lambing records 5 months later. The observations also suggested the existence of breed differences in the degree of ewe response to sudden ram presence.

An appraisal of the value of S. 59 red fescue (Festuca rubra L.) for grazing was made using ewes and lambs (Clun Forest in 1969, Welsh Mountain in 1970) at a site 305 m O.D. in mid-Wales. S. 23 perennial ryegrass (Lolium perenne L.) was used as a control, and the value of S. 184 white clover (Trifolium repens L.) in conjunction with both grasses was examined.

In the first year, under a rotational grazing regime at a fixed stocking rate of 22 ewes and single lambs/ha, lamb live-weight gains were significantly poorer on S. 59/S. 184 and significantly better on S. 23/S. 184 than on either of the pure grass swards. For the 130 days grazing season, mean daily lamb live-weight gains were 157, 126, 78 and 120 g on S. 23/S. 184, S. 23, S. 59/S. 184 and S. 59 treatments respectively.

During the second year lamb growth rates on S. 59/S. 184 improved by 59%, whereas those on the other treatments were marginally lower than in 1969. Stocking rates were increased on the grass swards and decreased on the grass/clover swards for most of the grazing period in the second year in accordance with herbage availability. No significant difference was detected between the four treatments in total lamb liveweight production as a result of better individual growth rates on the grass/clover swards.

In both years wide variations were recorded between treatments at different periods within the grazing season. Red fescue swards maintained superior lamb production in early spring and late autumn, but were inferior to ryegrass in mid-summer.

Herbage availability, intake and nutritive value were recorded on swards of S. 59 red fescue (Festuca rvbra L.) and S. 23 perennial ryegrass (Lolium perenne L.), with and without S. 184 white clover (Trifolium repens L.), and correlated with animal performance. Intake of dry matter was similar on all treatments. Animal live-weight gains during 1969 were positively correlated with digestible organic matter intake (DOMI).

Poor animal performance from red fescue swards in mid-summer was attributed to the rapid fall in digestibility at this time which affected DOMI.

Differences between treatments in efficiency of conversion of DOMI into live-weight gains were observed. Superior conversion ratios in swards containing clover could not be related to any of the herbage quality measurements recorded.

Better animal productivity from red fescue swards in early spring and in late autumn were related to the longer growing season of this grass.

The merits and demerits of red fescue as a grass for hill conditions and the possibility of reducing its limitations by breeding are discussed.

Two surveys, involving 288 lambs, were carried out on the effects of system of production on the melting (slip) point, iodine value, and fatty acid composition of perinephric and subcutaneous carcass fat. The systems studied were:

A, early Spring lambs fattened indoors on concentrates;

B, early Spring lambs off grass;

C, early Summer lambs off grass;

D, Autumn lambs off grass, and

E, Winter hoggets.

The melting point of both perinephric and subcutaneous fat increased progressively during the season from mean values of 41 and 32°C respectively in group A to mean values of 48 and 42°C respectively in group E. Discolouration of the surface fat was associated with the low melting points of group A.

Mean iodine values of both fats decreased progressively from group A to group E and this change was associated with a decrease in levels of oleic and palmitoleic acid and a corresponding increase in the level of stearic acid. In the fat, levels of myristic acid were highest in grass fed lambs while levels of linoleic acid were highest in the concentrate-fed lambs.

Within each group, perinephric fat contained more stearic and less oleic, palmitoleic, palmitic and myristic acid than subcutaneous fat.

Within animals, the levels between perinephric and subcutaneous fat of melting point, iodine value and most of the individual fatty acids were highly correlated.

Within animals also, the melting point of perinephric fat was correlated in decreasing order of significance with stearic acid, oleic acid, iodine value, linoleic acid and palmitoleic acid, while melting point of subcutaneous fat was correlated in decreasing order of significance with stearic acid, oleic acid, palmitoleic acid, iodine value, linoleic acid and total branched-chain fatty acids.

Four groups of six store lambs were offered ad libitum a concentrate barley-based diet, supplemented with either 8% casein or 2% urea, each contributing the same level of nitrogen to the diet and each fed with or without a supplement of 5·8% sunflower oil. Daily food intake was significantly affected by treatment but there was no significant treatment effect on live-weight gain or food conversion efficiency. In rumen fluid the casein supplement resulted in more total volatile fatty acids and a greater proportion of valeric acid, while the sunflower oil supplement significantly increased the proportion of propionic acid. Sunflower oil supplementation decreased the melting point of perinephric fat by about 3 °C, associated with an increase in the proportions of palmitoleic, oleic, linoleic and linolenic acids and a decrease in the proportions of palmitic and stearic acids. Sunflower oil resulted in a smaller and nonsignificant decrease in the melting point of subcutaneous fat which was associated with an increase in the proportions of linoleic and linolenic acid and a decrease in the proportion of palmitic acid. Melting point of both fats was not affected by source of dietary nitrogen supplementation but in subcutaneous fat the urea supplement resulted in a small increase in the proportion of oleic acid and a decrease in the proportions of palmitic and palmitoleic acids. The proportions of branched-chain and oddnumbered n-acids in both fats were not affected by treatment.

The sprout inhibitor Chlorpropham (CIPC) [isopropyl N-(3 chlorophenyl) carbamate] was found to be an effective sprout inhibitor in stored swedes (Brassica napus L.) under certain conditions. It was ineffective and unnecessary in swedes stored from November to April but necessary for those stored in clamps from March to July. CIPC did not, however, prevent rotting nor arrest normal chemical changes. Rotting developed because of the restricted ventilation necessary for successful use of CIPC and was more severe in mechanically than in hand-harvested roots. The main advantage of using CIPC to extend the storage and feeding life of swedes is that the absence of sprouts makes the handling of the roots much easier.

Friesian bulls fed swedes preserved with CIPC and supplemented with 50% conconcentrates gave satisfactory growth compared with similar bulls offered a diet containing only barley.

One pot and five field experiments were made to study different aspects of the competition between R. exaltata and maize.

The growth of young maize plants was not inhibited by being grown together in pots with young R. exaltata plants. In the field the soil tended to be somewhat wetter when the two species were grown together than when maize was grown alone, and was wettest with R. exaltata grown alone. Maize grain and total yield decreased and shoot yield of R. exaltata increased with R. exaltata plant density on both irrigated and unirrigated blocks of land, but yields were not much affected on either block by increase in plant density of maize or in nitrogen supply; maize yield was increased by irrigation but that of R. exaltata was not. Maize plant arrangement did not greatly affect maize grain and total yield or R. exaltata shoot yield, nor did arrangement of R. exaltata plants have much influence on their depression of maize yield, but R. exaltata caused a greater decrease in the grain yield of a short than of a tall maize cultivar.

R. exaltata plants germinating at the same time as the crop plants did not have much effect on maize grain yield if they were removed by 8 weeks after the seedlings emerged, but decreased it considerably if allowed to remain for 12 weeks or more; weeds sown 2 or more weeks after the maize emerged hardly grew and had little effect on maize yield. When maize and R. exaltata were grown together leaf area of the maize was little affected up to the time of flowering, but was decreased after flowering, while leaf area of the weed was greatly depressed. Up to 7–8 weeks after seedling emergence more of the ground area was covered by foliage when maize was grown with R. exaltata than when it was grown alone, but later the ground was completely covered by foliage in both cases. Dry weight of grain and shoot of maize increased and that of shoot of R. exaltata decreased when the weed plants were shortened with growth regulators.

The milk intakes of single-born Texel x Blackface and of pure-bred Blackface lambs suckling Blackface ewes was measured using a lamb-suckling technique. The shapes of the lactation curves were similar but the mean milk intake of the Texel x Blackface lambs was substantially greater than that of the pure-bred lambs at all points on the lactation curve. The Texel x Blackface lambs attained a mean maximum daily milk intake of 2418 g and the pure-breds 2075 g; mean total milk intakes during an 84-day period were 157 and 128 kg, respectively. Mean birth weights were 5·08 and 4·98 kg and the subsequent mean daily live-weight gains were 364 and 344 g, respectively, for the Texel x Blackface and pure-bred lambs. It is concluded that lamb genotype had a substantial and significant influence on the milk production of the ewes.

Estimates have been made of the amount of energy fermented and the amounts of microbial protein and total fatty acids synthesized in the rumen of sheep given various rations of hay and concentrates. The sheep had re-entrant cannulas in the proximal duodenum. The amount of protein synthesized was calculated from the flow of RNA-N at the duodenum. The change in the amount of total fatty acids between the food and the proximal duodenum was also measured.

In Expt 1, six sheep were given a low-protein basal diet and the same diet supplemented with a vegetable protein concentrate with or without tannin treatment. Some 72% of the digestible energy was apparently digested in the rumen and an estimated 150–170 g microbial protein were synthesized per kg organic matter apparently digested in the rumen. Differences due to the dietary treatments in the amount of energy digested and the amount of microbial protein synthesized were small and non-significant.

In Expt 2, the effect of a supplement of 20 g/day of cod-liver oil (CLO) on digestion of a mixed diet of hay and concentrates was examined in five sheep. Despite a marked fall in the ratio of acetic acid to propionic acid in the rumen volatile fatty acids when CLO was added, there were no clear differences in the amount of energy fermented in the rumen, which averaged 64% of the digestible energy, or in the efficiency of microbial protein synthesis, which averaged 200 g/kg organic matter apparently digested in the rumen. On the basal diet an increase of 6·7 g total fatty acid/day occurred in the stomach. This was presumably synthesized in the rumen. However when CLO was added to the diet, a decrease of 4·1 g total fatty acid/day was measured.