The influence of sex and gonadectomy on liveweight growth and its components was examined in a comparative slaughter experiment using Southdown – Romney cross lambs run under New Zealand pastoral feeding conditions.

Twenty ram lambs were castrated and 20 ewe lambs spayed at docking, at approximately 4 weeks of age. Ten ram and 10 ewe lambs were killed at this age and 5 lambs from each of the four ‘sexes’ (entire and gonadectomized, male and female) were killed 4, 8,12 and 24 weeks after docking.

Live-weight gain was higher for males than females and higher for entire than gonadectomized lambs, with some evidence of a greater depression in growth associated with castration than spaying. Effects on carcass weight followed those on live weight; weights for entire rams, wethers, entire and spayed ewes were 16.92, 14.72, 14.02 and 12.46 kg. respectively at approximately 7 months of age.

The influence of sex and gonadectomy on carcass grades, measurements and chemical composition is reported from a comparative slaughter experiment involving 100 Romney x Southdown cross lambs.

Grading results, although based on small numbers of carcasses, showed a tendency to down grade entire ram lamb carcasses.

Linear carcass measurements indicated some differences in conformation between the four ‘sexes’, although these were somewhat inconsistent over the two slaughter ages at which measurements were recorded. Relatively larger eye muscle areas were evident for gonadectomized than for entire lambs and for males than for females. Fat cover over the eye muscle was lower for entire rams than for the other ‘sexes’.

A study of the horizontal and vertical distribution of herbage in grass-dominant swards was made to assess the relative importance of different sources of wastage during grazing. A sward grazed by cattle under two contrasting managements was divided, for the purpose of herbage sampling, into two categories: ‘grazed’ herbage, on ground with no obvious dung contamination, and ‘dung patches’, which were of ungrazed or lightly grazed herbage resulting from the effects of faeces dropped at previous grazings. In each category, samples were cut at two successive heights to provide an estimate of the quantity of herbage in the upper region of the sward (over 2½ in. from ground level) and in the lower region (½-2½ in. from ground level).

After grazing, some 35% of the original crop remained in ‘grazed’ areas, and some 20% in ‘dung patches’. In terms of vertical distribution, most of the residue (40% of the original crop) was in the lower region, from ½ to 2½ in. above ground level.

Total production as live-weight gain was not significantly different, but the yield of conserved herbage was greater in treatment R (five rotations) than in treatment RR (nineteen rotations). Frequent grazing reduced herbage production, and this effect was not offset by any less intense defoliation of the frequently grazed sward. The average quantity of herbage residue was no higher in treatment RR than in treatment R, although the time of occupation per plot by the cattle in RR was only a quarter of that of the cattle in treatment R.

The half-carcasses from twelve Dorset Horn x Border Leicester-Merino lambs (3-5 months old) were used to investigate the relationships between the weight of the carcass and its cuts and their chemical composition. The specific gravity of the whole carcass and of the cuts was also measured.

Half-carcass weight and chemical composition were highly correlated. Weight could be used to predict the chemical composition with a reasonable degree of accuracy. The loin, the leg, the leg plus loin and the residual were shown to be highly correlated with the chemical composition of the halfcarcass. The loin and leg plus loin are the most convenient to use.

The effect of stocking-rate was measured on growth of indigenous oxen grazing Hyparrhenia veld and dambo. Stocking-rate had a relatively small effect on weight gain per ox in the rainy season when veld was relatively nutritious, but had a significant linear effect and a lesser quadratic effect on weight loss per ox in the dry season. Oxen stocked leniently on veld in the dry season lost less weight than heavily stocked oxen. Oxen fed a protein supplement, maintained or gained weight when grazing veld in the dry season even at high stocking-rates.

In long-term trials, compensatory growth so affected cattle weight gains that heavily stocked oxen which had large weight losses in the dry season compared with leniently stocked oxen, had greater weight gains in the following rainy season. Stocking-rate had a highly significant, linear effect on cumulative weight gain per ox, which was more evident on dambo grazing than on Hyparrhenia veld.

Six steers kept in an environment of 15°C. were deprived of water for four consecutive days. This treatment, by depressing appetite, caused a reduction in voluntary hay intake to one-quarter of its normal level and a decrease in body weight by 10%.

In spite of this reduction in feed intake, which must have been accompanied by a fall in metabolic heat production, the animals were less able to tolerate heat than when they were normally watered: during 4 hr. exposures to temperatures of 40.0°C. dry bulb and 32.5°C. wet bulb the waterdepleted animals showed higher values of rectal and skin temperature. This was associated with a slower initial rise and lower final values of respiratory rate (130 versus 155 respirations/min.).

The effects of applying CaCO3, MgSO4, 7H2O, (NH4)2SO4 and Ca(NO3)2 to the soil on the drymatter yield and Mg absorption of oats at the 4-5-leaf stage were studied in a factorial pot experiment with a Mg-deficient acid sandj soil.

Yield of dry matter was increased by all treatments, particularly CaCO3.

Applying CaCO3, MgSO4, 7H2O and Ca(NO3)3 generally increased % Mg and total Mg uptake of oats. Applying (NH4)2SO4, which reduced the % Mg in oats growing in the unlimed soil, generally increased % Mg where CaCO3 was also added. The rate of nitrification of NH4, which was slow in the acid soil, was greatly increased by applying CaCO3.

In an experiment to investigate the interrelationships of genetics and nutrition in the growth of cattle up to 2 years of age, five monozygotic and six dizygotic Ayrshire twin heifers were reared under close nutritional control on an all cubed diet.

Two control systems were used. Some animals were fed similar amounts of food, and differences in growth rate and efficiency examined while others were made to grow alike and differences in food consumption and efficiency examined. Overall, similarly fed animals had similar growth rates and efficiencies and similarly grown animals similar food intakes and efficiencies. Variation in growth, food consumption and efficiency was much less than in an ad lib. feeding system.

1. The effects of age of ewe, and year, sex and type of birth of lambs on lamb weights between birth and weaning were measured and appropriate correction factors estimated in a flock of East African Blackheaded sheep maintained over an 11-year period in Western Uganda. These correction factors were then used to examine the effects of a long dry season at different stages of lamb growth.

2. On birth weights the effects of sex ranged from 0-25 lb. to 0-40 lb.; twinning 1-0 lb.; gimmer's lamb 0-5 lb. On 2-month weights the corresponding adjustments were 0-2 lb.-l-4 lb.; 5-1 lb.; 1-7 lb. On weaning weights 0-3 lb.-2-9 lb.; 6-0 lb.; 2-6 lb.

3. A long dry season during late pregnancy did not appear to affect lamb birth-weights and a dry season between 2 months and 5 months of age did not affect lamb weaning weights. However a dry season during the main suckling period from birth to 2 months of age significantly lowered lamb weights at 2 months of age.

1. The mean daily live weight gains of lambs were used to estimate the milk production of ewes and gimmers during the first 8 weeks of lactation. Records of 1178 lambings of East African Blackheaded sheep between the years 1952 and 1962 were available.

2. Gimmers had significantly lower production than second and subsequent lamb ewes. Ewes rearing twins had a significantly higher yield than ewes rearing singles. There appeared to be no difference in yield between ewes producing twins but rearing singles, and ewes rearing natural singles.

3. A long dry season with resultant lowered plane of nutrition significantly reduced the live-weight gain of lambs.

1. The effects of birth weight, sex, twinning, parity of dam and dry season on mortality rates of lambs were studied between birth and weaning at 20 weeks in a flock of East African Blackheaded sheep.

2. The mean birth weights of non-surviving lambs were lower than those of surviving lambs. Singles from gimmers and twins from ewes were 0.5 and 1.0 lb., respectively, lighter at birth, and had higher mortality rates than singles from ewes. The overall mortality rate of singles from ewes was 16%, singles from gimmers 20% and twins from ewes 28%. Male and female lambs born alive had similar mortality rates (18%).

1. The effects of cutting herbage to either 1 in. or 2½ in. from ground level were studied at varying cutting frequencies in two experiments on a perennial rye-grass/white-clover sward. In one of the experiments the frequency of cutting was decided by the stage of growth of the herbage, and in the other it was decided on a time basis where cutting was carried out at intervals of 2, 4 or 6 weeks throughout the growing season.

2. Greater yields of herbage dry matter were obtained by cutting to 1 in. rather than to 2½ in. at all cutting frequencies in both experiments. This effect did not vary significantly with frequency of cutting where cutting dates were decided by the stage of growth of the herbage. However, where the cutting frequency was decided on a time basis, close cutting gave a relatively greater yield increase compared with lax cutting where the herbage was cut every 2 weeks instead of every 4 or 6 weeks.

3. The results suggest that the practice of cutting at an average stage of growth in previous experiments probably had little or no influence on the effects recorded for the contrasting closeness of cutting treatments.

1. In a grazing trial with sheep, cocksfoot, ryegrass and tall fescue were grown with and without white clover, under ‘short’ and ‘long’ management systems, and also white clover.

2. Live weights were recorded every 2-3 weeks, and wool production was estimated by clipping midside patches every month.

3. Sheep on grass plus clover plots were significantly superior to sheep on grass plots in terms of live-weight gain, final live weight and clean-wool production.

4. Sheep on ‘long’ pastures were significantly heavier than sheep on ‘short’ pastures for a month in the early part of the trial. Thereafter, differences in live weight were not significant.

1. In a grazing experiment with sheep, cocksfoot, rye-grass and tall fescue were grown with and without white clover, under ‘short’ and ‘long’ management systems.

2. One sheep on each plot was fitted with an oesophageal fistula, from which herbage samples were collected at fortnightly intervals. The botanical composition of samples from the mixed swards was estimated by an optical point quadrat method. Samples were analysed for crude protein and cellulose, and digestibility was estimated in vitro.

3. Treatment difference within the mixed swards were not significant in terms of botanical composition. The mean proportions selected were 73% grass, 9% clover and 18% dead matter. The proportion of clover selected did not differ significantly between sample collections.

A model relating the yield of shelled peas to maturity, as measured by the tenderomoter, has been given. The model has been fitted satisfactorily to data from pea experiments carried out over a period of 4 years and covering a range of plant densities and irrigation treatments. Comparison with other published work suggested that the model may be generally applicable to wrinkled-seeded varieties. A formula is given for interpolation of pea yields to a given maturity, although it was shown that linear interpolation is generally adequate.

The effects of varying static and changing moisture contents on mineralization of nitrogen after incubation (28° C.) for 3, 6 and 12 weeks were studied.

Mineral-nitrogen, accounted for entirely by nitrate, increased with increasing static moisture content up to 40-50% water-holding capacity (W.H.C). With further increasing moisture up to waterlogging, both mineral-nitrogen and nitrate decreased, the latter to negative values, indicating disappearance of nitrate originally present in the soil. Ammonia accumulated only at moisture contents above 50 % W.H.C. and its extent of accumulation increased with moisture content.

When soils with moisture contents of 10-50% W.H.C. during an initial 6-week period were changed to waterlogging for a second 6-week period, mineralnitrogen and nitrate accumulation decreased with increasing initial moisture in comparison with soils left at initial moisture contents for the second period.

1. Twenty-four individually fed yearling Ayrshire heifers were used to compare diets consisting of (1) long barley straw and concentrates; (2) the same quantities of similar foods as in (1) but with most of the barley straw ground and pelleted with a proportion of the concentrates in a ratio of 70:30; (3) replacement of the whole of diet (1) by the pelleted 70:30 mixture to provide a similar theoretical starch-equivalent intake.

2. Live-weight gains over an experimental period of 10 weeks were: treatment 1, 0.55 lb./day; treatment 2,0.99 lb./day; treatment 3,1.23 lb./day. These differences were statistically significant and indicated a marked response in energy value due to processing the straw.

Variations during 12 months in the concentrations of soil P and K soluble in 0-01M CaCl2 solution were measured on several sites with contrasted histories at both Rothamsted and Woburn. Concentrations were always less in fresh than in airdried soils.

P concentrations in the heavy soils at Rothamsted were remarkably constant, seasonal variation only occurring where FYM or phosphate fertilizers had been applied during the year. At Woburn P concentrations were also constant in the poorer soils, but varied during the year in rich soils.

On Barnfield at Rothamsted the plots receiving FYM each year contained more soluble P than those treated with superphosphate. Where both FYM and superphosphate were applied, P concentrations were greater than the sum of values on plots receiving FYM and superphosphate separately because a given amount of P remained more soluble when FYM was regularly applied. P also remained more soluble on plots given ammonium sulphate.

1. Two experiments were conducted in a lowtemperature cabinet. In the first experiment three grass varieties (two North African fescues and S 22 Italian rye-grass) were subjected to two cutting treatments (herbage cut from 8 in. to 2 in. and from 4 in. to 1 in.). Dry-matter production, dry-matter content and tiller number were recorded from plots of 9, 16 or 25 plants. The second experiment, a uniformity trial, was planted with a uniform population of a North African fescue. The optimum plot size and shape within the cabinet, and the optimum arrangement of blocks, was determined using a Titan autocode programme.

2. Treatment and variety differences could be detected using very small plots. For the material and apparatus used, an 18-plant plot was the optimum size.