Article by D. F. Osbourn and P. N. Wilson:

‘Effects of different patterns of allocation of a restricted quantity of food upon the growth and development of cockerels.’

Wherever Figure 1 is referred to in the text, Figure 2 is meant.

The caption to Figure 1 should be placed under Figure 2 which has no caption at all. The caption of Figure 1 should read ‘Curves showing the liveweight gains of cockerels on the three treatments, (g.)’

The ordinate on Figure 2 should read ‘daily food consumption (g.)’

A statistical analysis was undertaken to study persistency of lactation in buffaloes, using the milk records collected on a herd of buffaloes belonging to the Ministry of Agriculture at Sakha Experiment Station. The number of buffaloes included in this report was 328 animals having 722 lactations. A formula was developed for estimating persistency of lactation in buffaloes and results obtained are as follows.

The aim of this investigation was to study the repeatability and heritability of initial milk yield and persistency of lactation in buffaloes. The interrelationships between 305 days milk yield, initial milk yield and persistency were also investigated.

A description is given of a double change-over, grazing trial designed to test the value of Hyparrhenia veld grazing for milk production during the rains.

Three feeds were offered to lactating cows, and the effects of qualitative differences between the feeds were measured on milk yields. The treatments were:

The paper reports the results for six factorial experiments carried out over a period of 3 years, and designed to measure the effects of nitrogen, phosphate and potash on the yield of dry matter and to determine the effect of nitrogen on the phosphate and potash requirements of grass being cut five times per annum for conservation.

Heavy dressings of nitrogen reduced the percentage of dry matter in the fresh herbage, but produced a very large increase in the yield of dry matter. There were quite large variations in the response to this plant food, but 348 lb. N per acre per annum practically doubled the yield and generally the response curves were substantially linear.

The response to nitrogen depended on an adequate supply of potash and at five of the centres there were very large interactions between these two nutrients. The need for potash was greatest at the highest nitrogen rate and was much greater in the second and third than in the first year of the experiments.

At the highest nitrogen rate some of the responses to potash were very large. The yields of dry matter showed no large or consistent differences between applying 336 lb. K2O in one dressing during the winter months or applying this amount in five equal dressings, one for each cut. The results demonstrated the ability of the soils to supply potash and showed that the regular cutting and removal of herbage, especially if heavy dressings of nitrogen were applied, exhausted the potash reserves in the soil.

Phosphate had practically no effect on the yield of dry matter either in the presence or absence of nitrogen.

With adequate potash the production of dry matter per lb. of fertilizer nitrogen was practically independent of rate and the overall mean results are between 14·0 and 15·7 lb. In the absence of fertilizer potash there was a very large effect of rate: 15·0 lb. dry matter per acre was produced per lb. N with the 87 lb. N per annum treatment, 13·7 lb. with 174 lb. N and 10·0 lb. with the 348 lb. N treatment.

Approximately 70–75% of the annual production was obtained before the end of July. Thus 1 lb. of fertilizer nitrogen produced considerably more dry matter per acre during May, June and July than later in the season.

Evidence of natural selection for certain aspects of mating efficiency in swine are advanced based on preliminary studies with thirty-one sires, fiftyeight dams and their progeny. Selective fertilization was conclusively demonstrated. Variations in male and female mating behaviour were sufficiently large to indicate considerable non-randomness of mating frequency under the conditions of multiple sire mating (i.e. group exposure of dams to selected sires). The combined effects of the separate phenomena of selective fertilization and mating behaviour are discussed in relation to their evolutionary significance in animal breeding.

1. Fifteen experiments on spring barley (mainly Proctor), done from 1957 to 1959, compared alternative alternative methods of applying 0·3, 0·6 and 0·9 cwt. N/acre.

2. Combine-drilling 0·3 or 0·6 cwt. N/acre as ammonium sulphate produced higher mean yields than broadcasting, but drilling 0·9 cwt. N/acre checked early growth and reduced mean yields in two of the three seasons.

1. Evidence is presented to show that compared with an unmulched soil, a surface mulch reduces the nitrate-N levels significantly following an application of a nitrogen fertilizer during the rains.

2. Natural nitrate-X values in the top-soil were lower under a gravel mulch than a Napier grass mulch. It is concluded that the effect of a Napier grass-mulch cover in lowering natural soil nitrogen-N is offset in part by nitrates formed from the nitrogen it contains.

The work reported in two previous papers, Robinson (1960a, b) led to certain conclusions which required evaluation in terms of coffee yields (Coffee arabica Linn). The work describes changes in nitrate and ammonia-N in the Kikuyu red loam coffee topsoil, both natural and fertilizer derived, in the presence and absence of mulches.

This paper presents early coffee yield results which have been obtained from field trials laid down on the Coffee Research Station, Ruiru, Kenya, to measure the effect of treatments based on the conclusions drawn from the soil studies.

1. Pellets of L-thyroxine (30 mg.) were implanted subcutaneously in sheep. The loss in weight of the implants and the plasma P.b.i. level were determined at intervals.

2. The P.b.i. concentration increased within a few days from a normal value of around 5 μg./100 ml. to one of 15–20 μg./100 ml. After 10–20 days the concentration slowly returned to normal, and at 70 days subsequent to implantation was only slightly above the normal level.

1. A preliminary trial involving forty-six ewes demonstrated that when ewes in store condition were flushed for different periods, there was a marked increase in ovulation rate after 1 month with no further increase after 2 or 3 months. Flushing did not lead to ovulation rates higher than in ewes maintained in fat condition.

2. When similar ewes in fat condition were fed submaintenance diets there was no decline in ovulation rate while the animals had good body reserves, but as the period of submaintenance feeding was extended there was a gradual fall in ovulation rate.

3. In the main experiment forty-eight ewes were allocated to four groups of twelve ewes each. One group was fed a submaintenance diet till they were in moderately poor condition (submaintenance group). The other three groups were reduced to store condition and were then flushed on good pasture for 5–8 days, one oestrous cycle and two oestrous cycles, respectively. All ewes were slaughtered 2–5 days post-oestrus and half the ewes of each group were injected subcutaneously with 600 i.u. of P.m.s. on the twelfth or thirteenth day of the oestrous cycle prior to slaughter.

1. The energy metabolism and heat emission of two steers was determined at the maintenance level of nutrition in an environment of – 5, 5, 15, 25 and 35° C. and at a submaintenance level of nutrition in environments of – 5 and 19° C.

2. Shivering was observed at temperatures of – 5 and + 5° C. in both animals. Respiratory distress occurred at 35° C. being more severe in one animal than in the other. The animals stood for longer periods at the extreme temperatures.

3. The digestibility of food increased slightly as environmental temperature increased. Losses of energy as methane and in urine did not change in response to environmental temperature.

The theory of conducting trials of apparent digestibility is simple but the practical side is expensive and requires well-trained staff. In Uganda there is a very pronounced shortage of skilled technical staff and, because of this, equipment used must be as simple as possible to avoid errors of handling and analysis of herbage and faeces. The series of investigations carried out by the authors was planned to simplify the techniques and equipment used without decreasing accuracy to any significant extent. This paper deals with the simplified apparatus which was finally used.

Some techniques of sampling, preserving, drying and for determination of nitrogen content of faeces were investigated.

It was found that any sample between 100 and 600 g., made up of 10 g. subsamples taken at random, is satisfactory.

Untreated faeces and those preserved by the addition of acetic acid, hydrochloric acid or toluene were dried in a large oven at 80° C. and compared with untreated samples dried at 105° C. for 8 hr. Duplicate samples of those dried at 80° C. were exposed to room temperature for 7 hr. and then dried. When dry-matter and crude-protein contents were compared no significant differences were found between the three groups.

A method of combining dried faeces in order to reduce analyses of samples was investigated.

The effect of the length of digestibility trials and the number of animals required in relation to accuracy have been investigated and discussed.

As a result of our investigations the following procedure was adopted.

1. Unmuzzled milk-fed calves which ate considerable amounts of wood shavings after they were a few weeks old showed a much bigger increase with age in volume of rumen fluid and in flow rate of fluid out of the reticulo rumen than did muzzled milk-fed calves. It is suggested that these differences were due mainly to increased saliva production in the calves eating shavings.

2. Milk leaked into the rumen at feeding in eight out of twenty-four experiments. There was no indication that shavings ingestion increased the incidence of leakage nor that age up to 16 weeks had any marked effect. The leakage appeared to be a consistent characteristic of certain calves rather than a random occurrence and did not appear to affect adversely growth or health.

An objective, general classification of animal feedingstuffs in terms of their efficiency of use by pigs or ruminants can be made on the basis of earlier analyses of the relationships between the percentage crude protein and crude fibre contents of the dry matter of feeds and the differing digestibilities of c.p. and total nutrients by both classes of animal. It is shown to be in good agreement with the present empirical classification which is based on practical experience.

In an earlier paper the estimation of the total digestible nutrients (T.d.n.) to be expected in ruminant feedingstuffs has been described (Glover, J. Duthie, D. W. & Dougall, H. W. 1960). In a like manner the average T.d.n. in pig feeds can be estimated. The necessary equations have been obtained in earlier papers (Glover & Duthie, 1958A, b). They are, respectively

where C.p. and C.f. are percentage crude protein and crude fibre, respectively, in the dry matter of the feed, D.c.p. is digestible crude protein and N.r. the nutritive ratio. They can be used directly for the estimation of T.d.n. because by definition T.d.n. is D.c.p.(N.r. + 1); thus the T.d.n. to be expected at different levels of C.p. and C.f. can readily be calculated. Table 1 shows in abbreviated form some of the values that are obtained in the ranges 0–30% C.p. and 0–40% C.f., while Fig. 1 illustrates in detail the effect on T.d.n. of changing C.p. and C.f. levels of the diet. This figure shows clearly the very marked effect of increasing C.f. depressing the digestibility of the total nutrients in pig feeds, a fact which is already well known.

1. Two experiments designed to investigate the effects of different times of ploughing a clover ley on the growth and yield of the subsequent winter wheat crop are described and the results discussed.

2. Although the different times of ploughing led to considerable differences in the growth of the wheat, their effect on yield was not consistent. This in agreement with the results of an earlier series of experiments. The effects of time of ploughing are attributed mainly to the resulting differences in the physical condition of the seed-beds.

1. Twenty-nine experiments on sugar beet in 1957–59 compared ploughing-down of phosphate and potash in the previous autumn with spring application before the seed-bed preparations.

2. On average, spring application gave a higher yield of sugar and tops than ploughing-down, both in the wet summers of 1957 and 1958 and in the dry summer of 1959.