Growing beef cattle grazed six pasture types (all-grass or grass-legume mixtures) for 4 months on each. Live weight (mean of ten animals) and dietary energy concentration were measured at 2- or 3-weekly intervals. Values for feed intake estimated by back-calculating from feeding standards were on average 2·5% higher (range, 10% less to 12 % higher) than intake values estimated directly from dietary energy concentration and live weight. In contrast to this level of agreement of means, differences between methods within pastures were so large as to suggest the presence of overriding effects on predictors of voluntary intake. It was concluded that until these overriding effects are explained, there are no means of validating measured intakes in grazing cattle, or of accurately predicting the amount of beef produced from pasture.

Motes are cotton (Gossypium spp.) ovules that fail to ripen into mature seeds. These aborted ovules represent a loss in yield and can cause imperfections in yarn and cloth quality. The present study was conducted to determine whether 10 widely grown cotton cultivars differ in some boll characters that are undesirable for the textile industry. The bolls at the first positions of fruiting branches formed at 1st (bottom), 6th (middle) and 11th (top) nodes of the main stem were compared in 10 varieties in 2 years for the number of motes and their weights, mote production frequency, and long fibre mote frequency within a boll.

Mote frequencies and mote weights were affected by varieties and years. Moreover, mote frequencies were higher at the bottom and middle plant positions compared with the top position.

Fibre length for long fibre motes ranged from 18 to 21 mm. In both years, cultivars Deltaopal, Sayar 314 and Suregrow 125 had consistently lower mote and long fibre mote frequencies. Thus, these cultivars could be useful in breeding programmes to improve seed-set. Cotton breeders also need to consider long fibre motes in plant improvement studies.

L-methionine is a sulphur-containing nutritionally essential amino acid. It has a number of important roles in epidermal and dermal tissues of the integument of animals. Failure of normal function of these tissues in the hoof (claw) is a cause of lameness in cattle. Little is known about quantitative relationships between post-absorptive concentrations of nutrients including sulphur-containing amino acids and uptake and utilization by epidermis and dermis of the bovine claw. These parameters were studied at the tissue level by use of an established in vitro claw explant system using tissue from cattle of beef or dairy origin and L-[35S]-labelled methionine as tracer. The results showed that uptake of L-methionine by freshly prepared solear explants in Dulbecco's Modified Eagle Medium/F-12 Nutrient Mix (DMEM/F12) (1:1) medium containing 1·0 mmol L-methionine/litre was concentrative after 5–8 min, essentially linear for up to 10 min and became curvilinear thereafter. Maximum uptake and steady state conditions were obtained at approximately 30 min. Further measurements were made following 21 h incubation in culture medium. Under conditions of varying concentrations of L-methionine and measurement of uptake after 30 min, the presence of a saturable curve, that obeyed Michaelis–Menten kinetics, was demonstrated. Values of 3·61 mmol/litre and 5·84 mmol/kg intracellular water/30 min were obtained for KM and Vmax, respectively. Uptake was not influenced by L-cysteine and L-cystine concentrations in the culture media.

Similar culture and incubation conditions were used in subsequent studies of DNA and protein synthesis. These showed that rates of incorporation of L-methionine into protein fractions and stimulation of DNA synthesis measured by methyl-thymidine incorporation were dependent on L-methionine concentrations in the medium. Maximal rates occurred at approximately 50 μmol/litre, which is in the normal physiological range, and at 1% of maximum uptake capacity. Examination of histological sections by autoradiography showed localization of L-[35S]-labelled methionine in basal and suprabasal epidermal cells with limited retention in dermis. Measurement, by a range of histological, immunohistochemical, electrophoretic, western blotting and autoradiographic techniques, provided further evidence of L-methionine-dependent regulation of proliferation, differentiation and synthesis of proteins under physiological concentrations, by epidermal horn-forming cells.

A key role for L-methionine is suggested in the production of horn in bovine claw. The extrapolation of these in vitro data provides guidance for strategies to optimize methionine supply to claw tissues in vivo. Such extrapolation suggests the appropriateness of delivery of systemic concentrations of 50 μmol L-methionine/litre to maximize proliferative and protein depositional activity in solear epidermis and dermis in vivo.

A new, rapid method for the determination of cellulose has been investigated, and has been shown to yield a fraction composed mainly of hexosan. The method has been shown to be applicable to feeding-stuffs and faecal material, with a satisfactory degree of accuracy.

A comparison is made between a maize-rich diet containing 7% white-fish meal and a similar diet in which the protein supplement consisted of 6% ex. soya bean meal together with 0.3% L-lysine hydrochloride and 0.2% DL-methionine. The vegetable protein diet plus the amino acids proved in every way equal to the fish meal diet.

When the essential amino acids in the diet of weanling pigs are properly balanced as little as 10% digestible crude protein will support maximum growth.

The results obtained when 6% ex. dec. groundnut meal was used as a protein-rich supplement were not so favourable.

Stocking rates of 3, 6 and 9 acres per 2- to 3-year old steer on Acacia-Cymbopogonj Themeda complex pasture in Ankole, Uganda, demonstrated that 3 acres per head gave significantly lower individual live-weight gains, but that there was little difference between 6 and 9 acres over a 6-year period. Although cattle grazed at 3 acres averaged only 175 lb per head per annum, compared with 207 lb at 6 acres per head, the income was Sh. 34 per acre compared to only Sh. 20–50 at 6 acres per head. At 9 acres/head the return was Sh. 13–50 an acre.

A comparison of a 2 paddock/1 herd system with continuous grazing revealed no differences in production, despite the heavier capital investment involved in the former system. Growth rates at all three stocking rates were similar for most of the year, but in the dry season when all the cattle lost weight those stocked at 3 acres per head suffered the greatest losses (50–60 lb) and those at 9 acres per head the least (20–30 lb).

The purpose of the current study was to evaluate the effect of different levels of crude glycerine (CG, 810·9 g glycerol/kg) replacing dry ground maize on intake, digestibility, microbial nitrogen (N) synthesis and N utilization in grazing beef cattle. Five Nellore bulls (332 ± 29·6 kg initial body weight (BW)) were used in a 5 × 5 Latin square design. The animals grazed five Marandu grass (Urochloa brizantha cv. Marandu) paddocks of approximately 0·32 ha. Five supplements were evaluated: mineral supplementation (control, only ad libitum access to a mineral mixture) and 4 g of protein-energy supplementation/kg of BW with four levels of CG (0, 330, 660 and 1000 g/kg) replacing dry ground maize. Bulls that received protein-energy supplementation had greater organic matter (OM) pasture and digested OM (DOM) intakes than the control. No differences were observed among CG levels with regard to OM pasture, neutral detergent fibre and DOM intakes. However, ether extract intake increased linearly as CG levels increased. Protein-energy supplementation enhanced efficiency of microbial N synthesis, N balance and ammonia concentration, but they were not influenced by the CG levels. In conclusion, partial or total replacement of dry ground maize by CG in protein-energy supplements for grazing beef cattle exerted no changes on pasture intake, digestibility and N utilization. Therefore, the use of CG as an energy source in supplements for grazing cattle can be recommended.

In five experiments with binary mixtures of a wide range of Upland cotton varieties grown at three sites in Uganda in 1969–70 and 1970–1 there was no evidence to indicate that components interacted to give better yields than would be expected from their yield in pure stand. Moreover, in district variety trials over three seasons there was no evidence that mixtures of several lines of closely related material were more stable than the individual component lines. Problems related to a breeding programme based on the development of multiline varieties are discussed. Although the variable ecological conditions in Uganda should provide an excellent opportunity of developing multilines with a high degree of population buffering, it is concluded that pure lines tested in a wide range of environments are as good as, and are less costly to produce, than mixed populations that have been specially bred and tested. Multilines with components that differ little in yielding ability or stability do, however, provide an opportunity of more rapid seed multiplication, and there is also the possibility that multiline seed issues may show progressive increases in yield with each year of growing. Present practice in Uganda of releasing as seed issues multilines with closely related components that have been adequately tested as individual lines should therefore be continued.

1. Three completed series of laying trials involving the incorporation of calcium lactate in the diet are reported.

2. The addition of 1 or 2% calcium lactate to a layers mash results in a significant increase in egg production and/or the efficiency of the ration in terms of numbers of eggs per unit weight of food consumed. This effect has been obtained in birds at the onset of lay and also in birds that have been in lay for some 5 months.

3. The incorporation of 0·5% calcium lactate appears to be inadequate.

4. There is no evidence to date that the effect is attributable to dietary calcium, but the mechanism of action is unexplained.

5. Egg-weight, but not egg-quality, as judged by routine candling, is slightly lowered by feeding calcium lactate.

Extensive grazing experiments were conducted over four summer breeding seasons in north-west Queensland between 1984 and 1989. Ewes in the last third of pregnancy were grazed on Mitchell grass (Astrebla spp.) pastures of varying forb (herbaceous plant other than a grass) content. Pastures of low forb content (F-) were attained by stocking paddocks heavily with wethers prior to the experiment, or by selecting paddocks which already contained pastures of low forb content. Pastures of high forb content (F+) were kept without animals prior to the experimental period. Pastures comprised a range of forb biomass (29–828 kg DM/ha) and percentage forbs in total biomass (3–49%). Lamb marking percentage was found to be dependent on the biomass of forbs and proportion of forbs in the pasture, in two experiments. Ewes which grazed F+ pastures had lower lamb marking percentages than those grazing F- pastures.

Twenty pasture species collected during the experiments were analysed for the ratio of 13C: 12C and photosynthetic pathway was determined. Five forb and all three grass species had C4-dicarboxylic acid pathways, ten forbs had Calvin-C3 pathways and two forbs had crassulacean acid metabolism pathways.

Estimates of the proportion of C3 and C4 species in the diet were determined by analysing the ratio of 13C:12C in faeces. The apparent high proportion of Calvin-C3 pathway forbs in the diet of ewes compared to the proportion in the total pasture biomass indicated that ewes preferentially select C3 forbs in the diet, although there was no dependence of lambing percentage on the estimated proportion of C3 forbs in the diet. Management strategies that may improve lambing percentage in the Mitchell grass areas of north-west Queensland are discussed.

The growth and development of two new maize hybrids (FARZ 27 and FARZ 23) were studied in density experiments located at two contiguous ecological zones in Nigeria. The range of planting density used was from 2·6 to 6·6 plants/m2. Within this range, the relationship between dry-matter yield and density was asymptotic at final harvest. At the forest location of Jago (7·3 °N, 4·2 °E), both varieties attained optimum grain yield at planting density of 4·4 plants/m2, while at the derived savannah location of Alagunmu (7·8 °N, 4 °E), FARZ 23 attained optimum grain yield at 4·4 plants/m2 and FARZ 27 attained its optimum grain yield at 6·6 plants/ma2. This response of the new maize varieties to density treatments indicates that they could be planted at higher densities than are now used in the country.

Differences between varieties did not quite reach statistical significance but, at both locations, FARZ 27 produced more dry matter and grain per unit area than FARZ 23. FARZ 27 gave its higher grain yield mainly by producing more seeds per unit area than FARZ 23. Physiological measurements like net assimilation rate, crop growth rate and leaf area index were also higher for FARZ 27, although there were no significant differences between the varieties at most sampling dates. The partition of dry matter was identical in both varieties, although FARZ 27 showed a slightly better balance by partitioning more assimilates to the grain. Also, there was an indication of remobilization of stored assimilates from the stem to the grain in both varieties. Both varieties produced more dry matter and grain at the derived savannah location of Alagunmu than at the forest location of Jago. Physiological measurements were also higher at the derived savannah location.

Data from 266 pregnancies of 144 Finn x German Mutton Merino and Finn x Awassi ewes were used to determine the effects of season of mating, dam and sire breeds, litter size and sex of the offspring, and age of the ewe on the duration of gestation.

June, September–October and January matings resulted in significantly different durations of gestation of 143·3, 145·3 and 146·1 days, respectively.

Suffolk rams’ matings resulted in a significantly shorter gestation than matings with German Mutton Merino, Schwarzkopf or cross-bred rams.

A highly significant linear regression (b = –0·80) of the duration of gestation on the number of lambs was found.

Male lambs were carried longer than female lambs.

The intraclass correlation between the gestation periods for lambs which were maternal half-sibs was highly significant.

1. The visual judgement of bacon quality called the ‘proportion of lean to fat’ has been simplified by breaking down the overall assessment of the surface seen on the cut bacon side at the last rib into four simpler scores—of the ‘eye’-muscle size and shape, the amount and distribution of fat on the back rasher, the streak thickness and the proportion of lean to fat in the streak, each judged on a 10-point scale. An experiment is described in which eight experienced judges attempted to score these new characteristics in conjunction with the overall assessment.

2. The judging standard adopted in the overall assessment of the proportion of lean to fat varied less from batch to batch in this experiment (in which the seven batches were arrayed in fixed positions and assessed in one day) than in an earlier experiment (when the examples seen in each batch could be shuffled and the eleven batches were seen several days apart). The ranking of judges according to their discrimination and repeatability for the overall assessment was also changed in the second experiment.

Pigs from different companies (source populations) in years 3–5 of the Meat and Livestock Commission's Commercial Pig Evaluation were characterized in terms of eight production characteristics and grading measurements using canonical variates analysis in a multivariate general linear model. For pigs fed to a restricted scale, the first canonical variate was strongly associated with fat thickness measurements and the efficiency with which feed was converted into live-weight gain (FCR); the second canonical variate was associated with killing-out percentage. For pigs fed ad libitum, a discriminant variate formed from the sum of the first two canonical variates was strongly associated with P2 and loin fat thickness measurements and FCR, and a discriminant variate formed from the difference of the first two canonical variates was strongly associated with killing out, length and shoulder fat thickness. The first three canonical variates accounted for 88 and 90% of the variation between source populations for restricted and ad-libitum fed pigs respectively. A graphical display of the source populations indicated that there were six to eight groupings depending on feeding regimen.

In principal component analyses of residual variation, the first principal component on both feeding regimens was strongly associated with fat thickness measurements. The first three principal components accounted for 91 and 90% respectively of the variation for restricted and ad-libitum fed pigs.

Two flocks of 42 multiparous (M) and 27 primiparous (P) Nilotic ewes (Southern Sudan) were used in an experiment conducted at the Animal Production Research Centre, Khartoum N., Sudan, to study the effect of age and diet on reproductive performance. Each age group (M and P) was subdivided into two diet groups, fed either a sorghum (So) or a molasses (Mo)-based diet. The two diets were approximately isoenergetic (12·2 and 11·4 MJ ME/kg DM for So and Mo diets, respectively) and isonitrogenous (217 g CP/kg). These diets were formulated from sorghum and groundnut cake or molasses and urea as main sources of energy and protein, respectively. Each of the four diet groups of ewes was further divided into 6 subgroups (replicates) of similar body weights housed and fed together for two successive gestation periods. The results showed that the diet treatments had no significant effect on age and weights at first oestrous (210, 238 days and 22, 20 kg) and at first lambing (407, 418 days and 30, 28 kg) of the PSo and PMo groups, respectively. Age of the ewes and the diet treatments had no significant effects (P>0·05) on feed intake, conception weight, litter size, lamb birth weight, gestation period, postpartum anoestrous period, lambing interval, sex ratio of offspring as well as conception, fertility, abortion and lambing proportions. Primiparous ewes (P) had significantly (P<0·05) higher pre-weaning lamb mortality proportion, whereas the sorghum-based diet groups had higher (P<0·05) gestation body gain and lambing weights.

It was concluded that Nilotic ewes, compared with the other African sheep breeds reviewed, reach sexual maturity at an earlier age and are highly prolific due to their short postpartum anoestrous period. The results also highlight the importance of molasses and urea as efficient and good substitutes for sorghum grains and oil cakes, respectively, in the diets of ewes.

Dihaploids obtained from two tetraploids showed variation in tuber deformation resistance using a pendulum test and there were significant differences between them when used as parents in 2x × 4x crosses. Their ranking by tetraploid progeny means was the same as by clonal performance.

However, whereas the pendulum test was useful for the rapid measurement of rheological properties of tubers, there was found to be no correlation of control cultivar rankings using this test with those obtained using the squeezing test or farm survey data.

The effect of three different growth patterns from 15 to 40 kg live weight on the feed utilization of lambs was studied. The treatments were: high (H) ad-libitum feed intake, low (L) restricted feed intake and high-maintenance-high (HMH) ad-libitum feed intake from 15 to 25 kg followed by a 50-day period during which live weight was maintained constant, which in turn was followed by ad-libitum feeding. Animals were individually penned and fed a pelleted lucerne chaff-cereal grain mixture. Intakes of pellets were converted to digestible organic matter (DOM) using the results of in-vitro digestion studies. Two animals were killed at the start of the experiment (15 kg) and the remaining 27 animals (nine in each treatment) were killed at common live weights of 25, 30, 35 and 40 kg.

A marked reduction was observed during weight stasis at 25 kg in the amount of DOM required daily by the HMH animals to maintain live weight. Despite marked compensatory growth by the HMH animals which were rehabilitated after the period of weight stasis, DOM intakes were similar in both these HMH animals and a corresponding number of H animals over identical live-weight ranges.

Differences between treatments were found in DOM intake per unit live-weight gain (H < HMH < L), empty body-weight gain (H = HMH < L) and carcass weight gain (H < HMH = L) from 15 kg until slaughter. DOM intake was utilized more efficiently for gains of all these components by HMH animals during compensatory growth compared with H animals over the same live-weight ranges.

DOM intakes were related to energy gains in the carcass both for all animals in each treatment from 15 kg until slaughter, and for the H and HMH animals which were killed at 30, 35 and 40 kg from 25 kg. Comparisons of these data showed treatment differences in the efficiency of DOM conversion to carcass energy (H > HMH > L) and that DOM was utilized no more efficiently by HMH animals during compensatory growth than by H animals over identical live-weight ranges.

It is concluded that the increased efficiency of utilization of DOM for carcass gain during compensatory growth was due to changes in carcass composition during the period of weight stasis.

1. Dry-meal diets for pigs weaned at 6–7 lb. mean live weight and 6·9 days mean age were supplemented with antibiotic, pepsin and an α-amylase preparation according to a factorial design involving sixty-four pigs on eight treatments. Antibiotic was included in the respective diets from weaning to 40 lb. live weight and the enzymes from weaning to 25 lb. live weight.

2. Antibiotic supplementation gave a 12·5% increase in rate of growth from weaning to 40 lb. P < 0·001) by reducing the incidence of scour and increasing food consumption from weaning to 25 lb. Antibiotic exerted no effect upon efficiency of food conversion.

3. Pepsin supplementation increased the incidence of scour and reduced rate of growth by 3·7% whilst being fed (P < 0·1) and by 8·6% after it was omitted at 25 lb. live weight (P < 0·01). Efficiency of food conversion was reduced by 5·5% when pepsin was fed (P < 0·05) and by 4·6% after it was omitted at 25 lb. live weight (P < 0·1).

4. α-Amylase appeared to exert little influence upon either growth rate or efficiency of food conversion except in the presence of pepsin. It appeared to counteract the harmful effects of pepsin on growth rate from weaning to 25 lb. and on food conversion efficiency from 25 to 40 lb. This resulted in a 5·5% increase in growth rate during the first period (P < 0·01) and 5·7% improvement in food conversion efficiency during the second period (P < 0·05).

5. The overall effects of antibiotic, pepsin and α-amylase supplementation upon time taken to reach 40 lb. live weight were a reduction of 5·6 days, an increase of 3·8 days and a reduction of 3·9 days, respectively.

This study was carried out at the University of Ankara, Faculty of Agriculture, Field Crops Department experimental field during 1994–1996. Two flax (Linum usitatissimum L.) cultivars having two different flower colours were used as the study material. The cultivar with white flowers was used as a receptor and the violet coloured cultivar was used as a donor.

Average cross-pollination ratio was 1·81% in 1994 whereas it was 0·93% in 1995. The highest cross-pollination was obtained from third experimental design as 4·85% in 1994 and 3·21% in 1995. There were differences among the experimental designs in respect to cross-pollination. The results of this research showed that cross-pollination ratio decreased when distance between donor plants increased.

1. Two hundred and ninety-one samples of semen from seventy-four dairy bulls in use at seven artificial insemination centres and one bull-rearing centre were tested and graded according to the type of metabolic response under the experimental conditions described by Melrose & Terner (1953).

2. Conception rates of bulls were obtained from the breeding records based on not less than 150 first inseminations. Since the mean conception rates of centres varied, the fertility of each bull was assessed in relation to the mean conception rate of the centre at which the bull was standing. Bulls were considered of ‘high’ fertility when their conception rates were above, and of ‘low’ fertility when their conception rates were below a dividing line 5% below the mean conception rate of the centre.

3. A highly significant relationship (P < 0·001) was found between the groups of the metabolic responses and the fertility levels of the bulls. The practical application of the test in the assessment of the potential fertility of individual bulls is discussed.