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.

Ewe reproductive traits of imported Merino local Ossimi and Barki, their first crosses, backcrosses to Merino and the interbred groups of the backcrosses, were considered in this study. Records of 2168 ewes born from 1960 through 1970 were used in the study; they totalled 6959 records.

Reproductive performance was different in the three purebred groups, with more multiple births but more lamb losses and abortions in Merinos. However, the three groups weaned similar numbers of lambs/ewe run with the rams (0·98). Merino × Ossimi ewes had the best performance, they lambed and weaned 27% more lambs than local Ossimi. They were followed by MB ewes weaning 0·96 lambs/ewe run with the rams. Reproductive performance of the backcross ewes was lower than that of the first cross, but still better than the purebred groups. Inter-breeding of back-crosses reduced their hybrid vigour markedly.

Non-maternal heterosis contributed greatly to the reproductive performance of cross-bred ewes, while the effect of maternal heterosis on reproductive traits was fairly small.

Multiple births showed least heterotic effect.

Variation in urinary creatinine in nine male and twelve female buffalo calves divided into three equal groups on diets containing three levels of dietary protein intake (low, medium and high) was estimated. The variation in urinary creatinine (% and total) was large from animal to animal and also from day to day (P < 0·01) in the same animal. It was not affected (P > 0·05) by the level of dietary protein. The creatinine-nitrogen ratio decreased (P < 0·01) with increase in the protein level of the ration, but the creatinine coefficient (creatinine per kg body weight) did not differ significantly (P > 0·05). The male and female animals responded similarly.

It was concluded that urinary creatinine (% and total) and the creatinine coefficient cannot be used as an index either in nutrient balance studies or for evaluating ruminant nutrition in general. The creatinine-nitrogen ratio could also not provide a suitable yardstick to evaluate protein status of the animals because of the significant interaction of days × protein. The nitrogen balance is considered to be better for this purpose.

Teat orders were determined for 76 litters of Large White and Large White × Landrace pigs. Regression analysis within litters revealed a relationship between suckling position and weight both at birth (P<0·01) and at 3 weeks of age (P<0·001), with the heavier piglets tending to occupy the more anterior teats. The correlation coefficients, however, were very small (r = –0·16 and –0·22 respectively). The correlation between birth weight and 3-week weight was much larger (r = +0·47); and a comparison of pairs of litter-mates showed that a difference in birth weight of 0·25 kg or more persisted at 3 weeks in the majority of cases, regardless of which piglet suckled the more anterior teat. Birth weight accounted for much more of the variation in 3-week weight than did teat number, and, when the effect of birth weight had been taken into account, teat number accounted for only an additional 2·3% of the variation. Even so, the anterior teats did appear to confer some advantage which was independent of that of the birth weight of the piglets suckling these teats. From the results of this and other studies it is concluded that there is only a weak relationship between suckling position and weight at birth and 3 weeks. Other unidentified factors are probably of more importance for the within-litter variation in weight gain of suckling pigs.

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.

Nineteen feedstuffs were evaluated for total digestible nutrients (TDN), digestible energy (DE) and metabolizable energy (ME) using growing pigs. DE values, on a drymatter basis, ranged from 1570 kcal/kg D.M. (grassmeal) to 4890 kcal/kg D.M. (BP Grangemouth protein). ME averaged 97·4% of DE for cereal feeds and 81·9% of DE for protein feeds, the ratio of DE to ME being significantly affected by the crudeprotein content of the feedstuff:

ME/DE × 100 = 99·7–0·18 × crude protein (%): r = –0·94; P < 0·01.

TDN was more closely related to ME than DE:

DE (kcal/kg D.M.) = 45 TDN + 156: r = 0·92; P < 0·01,

ME (kcal/kg D.M.) = 43 TDN + 71: r = 0·98; P < 0·01.

ME values were corrected to both 30% and 0% nitrogen retention. Correction to 30% retention caused a maximum change of 3% in ME value while correction to 0% retention had a variable effect related to protein content of the feedstuff:

(ME(N0)/ME) × 100 = 98·3–0·113 × crude protein (%): r = –0·80; P < 0·01.

Eighteen individual feedstuffs and 19 mixed diets were used in a study attempted to relate determined energy values to various chemically determined measures. For cereals the level of fibre could be used to predict digestible and metabolizable energy (DE and ME). In the case of DE the relationships with crude fibre and modified acid detergent fibre (MADF) based on 14 feeds were:

DE (kcal/kg D.M.) = 4179–86 MADF (%): r =–0·96; P < 0·01,

DE (kcal/kg D.M.) = 4228–140 x crude fibre (%): r =–0·97; P < 0·01.

For all feeds the following equations gave the best prediction of energy values from dietary analysis (on the basis of correlation coefficients and residual standard deviations):

DE (kcal/kg D.M.) = 109·9 x crude protein (%) + 149·3 x acid ether extract (%) + 90·1 x nitrogen-free extract (%)–5030: R = 0·95; P < 0.01.

ME (kcal/kg D.M.) = 99·5 x crude protein (%) + 144·7 x acid ether extract (%) + 87·8 x nitrogen-free extract (%)–4795: R = 0·94; P < 0·01.

Digestible nutrients were closely related to DE and ME, e.g.

DE (kcal/kg D.M.) = 52·9 x digestible crude protein (%) + 108·3 x digestible ether extract (%) + 39·4 x digestible crude fibre (%) + 39·9 x digestible nitrogen-free extract (%) + 183·7: R = 0·99; P < 0·01.

The development of stable suckling order, the incidence of fighting when suckling, weight gain during the suckling period, and the severity of facial wounding were studied with litters of piglets in which the canine and lateral incisor teeth were either clipped at birth or left intact. Facial wounding was largely confined to litters with unclipped teeth. Severity of wounding correlated with the observed incidence of fighting on the udder (P<0·01); and both wounding and fighting were more common among litters comprising a large number of piglets (P<0·05). When the effect of litter size was taken into account, there were no substantial differences in weight gain to 3 weeks between piglets with high and low scores for facial wounding, nor between clipped and unclipped litters. Piglets which habitually occupied the most anterior or most posterior teats had less facial wounding than middle-suckling piglets, and showed greater consistency in teat choice. No gross differences between clipped and unclipped litters were observed in the development of stable suckling order during the first week of life. It is concluded that the ‘eye’ teeth, although used in disputes over teat choice, have little influence on the frequency of such disputes or on the original development of stable suckling order.

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.

Skin samples were used to evaluate the developing skin follicle population of Cheviot × Dorset Horn cross foetuses. The follicle population was studied from the first appearance of skin follicles (55 days' gestation) to the end of gestation. The pattern of development of primary and secondary follicles is described, and compared with the data available for other breeds. The occurrence of secondary follicle branching, previously confirmed only in the Merino, is described, and the ‘prenatal check’, an important feature of follicle development which had not previously been investigated in prenatal studies, is briefly discussed.

Following a 14-day uniformity period when they were stall-fed to appetite on a grass silage-grass ration, 18 cows in mid lactation were allocated to three treatments on which they received during the following 28 days either 100%, 75% or 50% of their previous voluntary feed intakes.

Treatment effects were measured on milk yield and composition, live weight, liveweight change and fasted live-weight change. Twice during uniformity period, and on the 7th, 14th, 22nd and 26th days of the treatment period, samples of jugular blood were obtained from each cow immediately before and 3 h after the first meal of the day. These were analysed for percentage packed cell volume, blood acetone and β-hydroxybutyrate levels, plasma glucose, non-esterified fatty acid, and total fatty acid concentrations.

Alternative methods of collecting blood samples, involving cannulation of the vein and venipuncture, were compared. Obtaining samples through cannulae took nearly three times as long as by venipuncture, but the method of sampling did not significantly affect the concentrations of individual blood metabolites. Blood samples collected before as contrasted with after feeding had significantly higher concentrations of nonesterified fatty acids and glucose, and lower concentrations of acetone and β-hydroxybutyrate.

The feed requirements of the cows were assessed using data on live weights, fasted live-weight change and milk production by calculating the regression of estimated net attributable energy/kg LW0·75 on digestible energy intake/kg LW0·75, from data for the full 28-day period. The maintenance requirement was 124 kcal net energy/kg LW0·75, and the efficiency of conversion of digestible energy to milk and body-tissue loss or gain was 60%. These data were used with each animal's live weight, milk yield and liveweight change appropriate to each blood-sampling day to calculate individual feed requirements on every occasion. Ratios of actual feed consumed to estimated requirements were calculated subsequently to provide quantitative indices involving all cows and feeding levels. Regressions of these indices on individual blood metabolites were examined to assess the value of the latter as predictors of the relative nutritional status of the cows as defined in this way. Of the blood metabolites studied, only plasma NEFA were consistently significantly correlated with these indices, and relationships were specific to each feeding level. Thus although, at a common feeding level, plasma NEFA can be used to categorize lactating cows according to degree of nutritional stress, they will have limited values as predictors if applied indiscriminately to the wide range of feed availabilities and intakes which exist between herds at similar stages of lactation.

The results have been discussed relative to previously published work, mainly with sheep and beef cattle.

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.

A technique for estimating the intake of liquid supplements by individual, grazing animals was used in a trial with 200 sheep grazing poor quality pasture and given access to a urea-molasses supplement (19%, w/v).

A mathematical procedure was developed to estimate intake of supplement based on measurements of the accumulation of tritiated water (TOH) and its rate of turnover in the body of each animal after a TOH-labelled mixture had been available for a period of 7 days.

In calculating the level of intake of labelled supplement, it was assumed that each animal ingested the mixture once daily over the 7-day period, since animals were observed to take the supplement daily and the daily loss of supplement from the dispenser was noarly constant. It was estimated that the combined intakes of the animals accounted for 87% of the known total loss of labelled supplement from the dispenser.

Of the 200 sheep, 97 did not consume any supplement and among the other 103 animals, estimated intake varied from 5 to 550 ml/day.

All sheep lost body weight during the trial, but those consuming the supplement lost significantly less weight, and grew significantly more wool during the period of supplementation, than did the sheep that did not consume the supplement.

A small but significant amount of the variance (13%) in body-weight change and wool growth during supplementation was removed by multiple regression analysis, by including the intake of the supplement, faecal egg count (as an indication of parasite burden) and body weight at the start of the trial, as independent variables. Other factors not studied (e.g., dry matter intake) apparently accounted for a large proportion of the variance.

The relationship between body-weight change and intake of the urea-molasses mixture was compatible with the hypothesis that the supplement was used largely as a concentrate feed, and not solely as a nitrogen supplement.

Two experiments were made in successive years in which three frequencies of watering were combined factorially with several rates and methods of applying nitrogen. Soil water content and leaf water potential were measured. The least frequent watering treatment decreased yield and nitrogen applications increased yield. All of the effect of water and most of the effect of nitrogen were associated with changes in the number rather than the weight of bolls. Although the combination of heavy nitrogen with frequent watering caused the crop initially to set fruit more slowly than did heavy nitrogen with infrequent watering, it prolonged flowering and increased the number of fruit ultimately set. Thus yield and the potential duration and cost of insect control were also increased. There were no differences in yield nor rate of setting between the following methods of application of the nitrogen: all applied to the seed bed; split application between the seed bed and side dressing 2 months later; and split application between the seed bed, side dressing, and irrigation water. However, when application was split so that most was applied in the water, the response was not as great. Application of nitrogen combined with frequent watering decreased the weight of the early bolls by decreasing fibre per seed. Nitrogen increased the weight of later bolls by increasing the number and weight of seeds. The practical and physiological implications of these results are discussed and a crop nutritional hypothesis for cotton developed further.

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.

Four rates of nitrogen fertilizer, three dates for the last application of water, and two varieties were combined factorially in two experiments in successive years. Leaf water potential was measured. There were large yield responses to water and nitrogen; in both cases the response in number of bolls was relatively twice as great as that in boll weight. Because one effect of nitrogen was to prolong the setting of bolls, which required continued watering for its full expression, there was an interaction between the nitrogen and water treatments which affected number of bolls, and thus yield. Deltapine 16 yielded more than Acala 1517BRI and responded more to nitrogen than did Acala 1517BRI. Heavy nitrogen rates decreased the initial rates of boll setting of Acala. Weekly picks of open bolls showed that, with early cessation of water and with the lightest rate of nitrogen, the boll weight decreased in the fourth and subsequent picks. This effect of nitrogen was more marked in Acala. These responses were analysed into the components of boll weight and are discussed in relation to the timing of the development of the bolls in order to explore the physiological implications. Nitrogen and water delayed harvest by prolonging effective flowering, by increasing boll maturation period, and by increasing the number of defoliant sprays required.

In a field experiment sunflower plants were subjected to soil water stress (SWS) at — 15 bar during stages of slow elongation, rapid elongation, flowering and ripening.

Significant decreases in yield, 100-seed weight and oil content were found as a result of SWS. The treatment resulted too in less evapotranspiration and a better water economy for production of seeds and oil.

The iodine value but not the acid or saponification values of the oil was affected by SWS. No qualitative differences in oil composition occurred at different treatments. However, percentage of oleic acid was higher than that of linoleic acid; SWS resulted in a clear tendency for an increase in the ratio of oleic/linoleic acids especially for plants subjected to SWS during elongation stage.

Sunflower plants were more sensitive to SWS during the elongation and flowering stages than during ripening stage

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.

Sebum was collected from pre-cleaned areas on the skin of Ayrshire calves at a fixed time using a cup and solvent technique, extracted and weighed. The rate of sebum output decreased with time and after 18 h there was very little increase in the weight of sebum on the skin surface. Sebum output over a period of 3 h was not statistically different between animals of different ages but tended to be higher in castrated males than in females and was lower in winter than throughout the remainder of the year.

Two methods of analysis of variance of experiments involving diallel arrangements of binary mixtures and monocultures where the former are each represented by a linear replacement series (de Wit, 1960) to detect mean quadratic and quartic patterns among the monocultures and different mixture types, and array differences with respect to linear, quadratic, cubic and quartic effects are given. These are applied to data from an experiment on Italian ryegrass where the four varieties 1145 and S. 22 (diploid), IG2 and Tetila (tetraploid) are mixed in the proportions 75:25, 50:50 and 25:75.

Significant mean quadratic effects for D.M. yield at certain harvests are due to higher yields from monocultures than mixtures, and a mean quartic effect at one harvest reflects a lower yield from 75:25 mixtures than 50:50 mixtures or monocultures. Array differences for linear and quadratic effects are largely a property of the ploidy contrast. Specific mixture effects were recognized for two varietal combinations, mixtures between the two tetraploid varieties showing some yield depression, and those between the two commercial varieties (RvP and Tetila) a considerable increase. No meaningful significant effects were detected for in vitro digestibility.

Further analysis of total D.M. yield by means of the regression of array covariance (Wr) on to array variance (Vr) show, as expected, a closer relationship of Wr and Vr with the non-recurrent component at a frequency of 75% than at 50% or 25%, but the significant departure of the slope from unity is interpreted as evidence that no reliable information as to the relative competitive abilities of the varieties can be obtained from these statistics. Examination of the de Wit replacement graphs strongly suggests a ranking of competitive ability which accords with the known morphology of the varieties.