Showing papers in "The Journal of Agricultural Science in 1967"

The use of biochemical parameters in controlling nutritional state in pregnant ewes, and the effect of undernourishment during pregnancy on lamb birth-weight

Abstract: 1. Fifty-one Scottish Blackface ewes were divided into three groups and individually fed throughout the latter half of pregnancy: (I) in excess of nutrient requirements, (II) to produce a uniformly moderate degree of undernourishment during the last 6 weeks of pregnancy, and (III) to produce a uniformly severe degree of undernourishment during the last 6 weeks of pregnancy,2. The prescribed levels of undernourishment were maintained by weekly adjustments of feed intake based on plasma FFA levels (group II) and plasma ketone levels (group III). The use of the technique is discussed.3. Undernourishment during the latter half of pregnancy reduced birth weights of single and twin lambs after adjustment for weight of the dams to the same extent. In the moderately undernourished ewes the reduction was approximately 10%, and, in the severely undernourished ewes, approximately 25%.

Growth, Water use and nutrient uptake from the subsoil by grass swards

Abstract: 1. Plant nutrients, N, P and K, were applied to the soil surface or injected at a depth of 18 in. or 30 in. in perennial ryegrass swards, when the upper horizons of the soil profile were dry.2. When the surface soil was dry and a soil water deficit of 2 in. existed there was no response to surface applied N but injection of N into moist soil at a depth of 18 in. produced a marked increase of growth. At this depth of injection there was a significant positive interaction between N and PK.3. There was a substantial recovery in the herbage (59–80%) of the nitrogen applied to the subsoil, provided water was available in the soil horizon in which the nitrogen was applied.4. Failure of a grass sward to regrow after cutting when the water available to the plant has been removed from the uppermost soil horizons is largely due to a deficiency of plant nutrients in the subsoil. The major deficiency is that of nitrogen.

The seasonal growth of pasture grasses

Abstract: 1. Twenty-one varieties of pasture grasses, including ten bred varieties, were grown on fertile soil for 3 years. Figures are presented of the rate of production of herbage cut every 3or4 weeks. Plots were cut in staggered sequence to permit growth intervals to overlap and to allow frequent assessments of the rate of production.

The effect of different levels of nutrition during late pregnancy on the subsequent milk production of Blackface ewes and on the growth of their lambs.

Abstract: 1. Using blood plasma FFA and ketone values to assess the nutritional state of individual ewes, high (H), medium (M) and low (L) planes of nutrition were imposed on 3 groups of Blackface ewes during pregnancy. By this method, ewes bearing single or twin foetuses were equally well or severely undernourished within treatment groups. The effects of these planes of nutrition during pregnancy have been assessed in terms of milk production, lamb growth, and live-weight changes by the ewes duriug their subsequent lactation. Immediately after parturition all ewes were individually fed a pelleted food ad lib. and their voluntary food intakes recorded. From 5 weeks of age individual voluntary intakes of solid food by the lambs were also recorded. Because of insufficient pen accommodation group-M ewes and lambs were discarded after 5 weeks of lactation.

The effect of plant density upon the growth and yield of barley

Abstract: 1. Cereal plant density affects yield and growth parameters of fundamental importance. An experiment is described in which growth and development, and yield and yield components of barley grown over a wide range of density were examined.2. Four varieties of barley—Proctor, Plumage-Archer, Domen, and Moore—were grown at densities approximately equivalent to 35, 70, 140 and 280 lb/acre. Density was found not to affect seedling establishment or plant survival, but there was a variety effect on seedling establishment.3. Varietal differences were seen in maximum tiller number, and the percentage of tillers surviving to form ears. These differences were most marked between the six-row variety and two-row varieties. The effect of increasing density was to increase the maximum tiller number, but this was followed by different rates of tiller death until early June, after which there was no further compensation for tiller number. Ear emergence and ear number were affected both by variety and density.

Leys and soil organic matter: II. The accumulation of nitrogen in soils under different leys

Abstract: 1. The nitrogen content of an arable soil to 15 cm depth, sown to a ryegrass/white clover sward increased on average by 0·005 % N each year.2. Under a grass sward without clover and without fertilizer nitrogen, there was an increase of 0·017 % N in 3 yeais in the top 7·5 cm of soil; an annual addition of about 70 kg N/ha.3. Including white clover in grass swards not receiving nitrogen fertilizer resulted in an increase over 3 years of 0·026% N to 7·5 cm depth in one experiment, and 0·014% N to 15 cm depth in another, an annual increment of 100–110 kg N/ha.4. The increase was greater under ryegrass/white clover swards than under cocksfoot/white clover swards. A similar difference was found both in accumulation of organic carbon and in clover content. In an experiment comparing many different grasses it was not possible to distinguish differences in the level of soil nitrogen, after 4 years under grass, which could be ascribed to species or strains.There was no significant effect of nitrogen fertilizer applied at rates of up to 314 kg N/ha per year for 3 consecutive years.

Investigations on the physiology of yield in winter wheat, by comparisons of varieties and by artificial variation in grain number per ear

Abstract: Elliott (1962) estimated that the average grain yield of wheat in the United Kingdom increased by 6·1 cwt per acre between 1947 and 1957. By considering results of yield trials carried out by the National Institute of Agricultural Botany he attributed 3·8 cwt of this increase to greater yielding ability of new varieties and the remainder to ‘other factors’, including the increased use of fertilizers, chemical weed control, better seed dressings and combine harvesters. The genetic improvement obtained by breeding new varieties is due partly to the incorporation of characters which are comparatively easily recognized, such as resistance to various diseases and lodging. However, even when these major limiting factors are absent from the environment the new varieties give higher yields, presumably due to physiological superiority. Many investigations, reviewed by Thome (1966), have sought to identify and establish the relative importance of the responsible physiological characters, but the information is still far from complete. This shortcoming is now the chief hindrance to more efficient choice of varieties for use as parents and selection of improved genotypes by the breeder. The objective of the three experiments reported here was to provide further information on the physiological basis of varietal differences in yield in wheat.

Calorimetric studies on the utilization of dietary energy by the laying White Leghorn hen in relation to plane of nutrition and environmental temperature

Abstract: 1. Calorimetric experiments on the utilization of dietary energy by the laying White Leghorn hen are described.

A comparison of the effects of white clover ( Trifolium repens ) and of perennial ryegrass ( Lolium perenne ) on fat composition and flavour of lamb

Abstract: 1. The carcass composition, the composition and characteristics of the subcutaneous and longissimus dorsi muscle fats, the volatile fatty acids of the rumen-reticulum fluid and the degree of flavour and odour of the cooked 12th rib chops of two groups each of fifteen Southdown–Romney cross ewe and wether lambs fed respectively white clover and perennial ryegrass have been determined. The lambs had been on treatment for 5 months and were slaughtered when about 9 months of age.2. The white clover-fed lambs had a mean live weight at slaughter of 94 lb ± 9 lb compared with 67 lb ± 7 lb for the perennial ryegrass-fed lambs. The carcasses of the white clover-fed lambs had greater (P < 0·01) amounts of fat.3. The iodine values of the subcutaneous fats of the white clover-fed lambs were highly significantly greater than those of the ryegrass-fed lambs and this result was consistent with the greater deposition of endogenous fat.4. The extra fatness of the white clover-fed lambs was consistent with their greater production of rumen-reticulum volatile fatty acids.5. The maj or differences in fatty acid composition of subcutaneous and intramuscular fats between pasture treatments were the highly significant increases in shorter-chain saturated and C15 branched-chain acids of the ryegrass-fed lambs. In addition, the subcutaneous fat of the ryegrass group contained highly significantly more octadecadienoic and octadecatrienoic acids while the 1. dorsi fat of the ryegrass group was highly significantly richer in stearic and oleic acids.

Energy requirements of the pregnant ewe

Abstract: Fifty-one Scottish Blackface ewes were divided into three groups and individually fed throughout the latter half of pregnancy: (I) in excess of their nutrient requirements, (II) to produce a uniformly moderate degree of undernourishment throughout the final 6 weeks of pregnancy, and (III) to produce a uniformly severe degree of undernourishment during the same period.Marked differences were evident in the amounts of feed required to maintain the prescribed nutritional states, and within the undernourished groups, between ewes with single and twin foetuses. In both groups of undernourished ewes the amount of feed required to maintain the prescribed level of undernourishment during late pregnancy was strongly related (P < 0·001) to birth-weight. The additional nutrient requirement of the ewe in late pregnancy was estimated to be 100 g D.o.m./kg foetus/day.

Control of the annual rhythm of breeding in ewes: effect of an equatorial daylength with reversed thermal seasons

Abstract: 1. Three groups of seven Southdown and seven medium wool Peppin Merino ewes were subjected, respectively, to seasons of daylength corresponding to a latitude of 60° S., reversed seasonal lighting (60° N.) and an equatorial daylength with reversed thermal seasons, for 2½ years. During the next 20 months group 1 continued as before. Group 2 had a 32-week photoperiodic year and group 3 had a 32-week thermal year with equatorial daylength.

Voluntary intake of low-protein diets by ruminants: II. Intake of food by sheep

Abstract: 1. A study was made of the voluntary intake of hay of low nutritive value by sheep when given four different amounts of concentrate foods (9, 18, 27 and 36 g/kg W0.73/day) each providing three levels of protein (1·3, 2·6 and 3·9 g DCP/kg W0.73/day). Hay alone was offered as a separate treatment. The trial was designed as an incomplete Latin square with thirteen treatments, thirteen sheep and four replicates. 2. Voluntary intake of low-protein hay by sheep was invariably lowered when they were given increasing amounts of concentrates. Hay consumption was also affected by level of supplementary protein; intakes increasing sharply from the lowest level provided (1·3 g DCP/kg metabolic body weight) to maximal intakes when about 3 g DCP/kg W0.73 were given to the sheep. 3. Total food and digestible energy (DE) intakes were similarly affected by changes in dietary protein level. Successive increments in concentrate allowances, except at the highest level of concentrate input, caused corresponding reductions in hay intake so that total food consumption remained similar (when protein level was kept constant). In consequence, DE intakes rose to maxima when approximately 30 g concentrate/kg W0.73/day were fed to the sheep.

Soil water use and growth of a grass sward

Abstract: 1. The rate and pattern of water extraction from the soil by grass swards were examined.2. Under a continued drought water was removed progressively down the soil profile. The rate of removal of water was similar from all horizons to a depth of over 3 ft in these conditions.

Quantitative observations on pig embryos of known ages

Abstract: 1. The lengths and weights of 241 pig embryos, aged 26–109 days, were recorded; the pregnant sows were from a mixed herd of Landrace, Large White and Wessex stock and some of their crosses. 2. An empirical linear regression of length on age was estimated (equation 1); the relation between weight and age was represented by a polynomial weight and age was represented by a polynomial (equation 2). We thank Mr A. S. Cray and the other directors of Unigate Ltd. for giving us the pigs; Mr P. Sedgewick of that Company gave us excellent co-operation. Prof. C. W. Ottaway and Dr P. Radford helped us throughout the investigation.

The influence of dietary calcium and phosphorus concentration on their absorption in the cow

Abstract: Experiments were carried out in dry, nonpregnant cows by varying dietary concentrations of calcium and phosphorus. Calcium and phosphorus absorption were measured by balance and isotope techniques. It was found that absorption of calcium or phosphorus increased when the dietary intake of the element increased, but only for a few days.

Retention of calcium, phosphorus, magnesium, sodium and potassium by the developing sheep foetus

Abstract: 1. Data on the fresh weight, mineral and fat composition of foetuses from Border Leicester / Cheviot ewes were obtained for seven singletons, fourteen sets of twins and four sets of triplets. The age of the foetuses ranged from 80 to 144 days. The foetuses were dissolved individually in concentrated nitric acid and the mineral composition of the resultant solution determined.

Plasma lipids of newborn and adult ruminants and of lambs from birth to weaning

Abstract: The plasma lipid concentrations of newborn lambs, kids and calves and of adult ruminants in 0various physiological states have been reported. In newborn ruminants plasma lipid concentrations were 20–40 % of those found in their dams at parturition.The concentrations of blood lipids have also been estimated in five lambs from birth to weaning at 90 days post partum. The plasma free fatty acid concentrations rose to a maximum at about 45 days post partum and then declined. Possible reasons for this elevation in plasma free fatty acids have been discussed with reference to published data on age changes in lambs of plasma glucose and volatile fatty acid concentrations. The concentration of plasma esterified lipids, mainly phospholipids and cholesterol esters, were very low at birth and rose to reach maximum values at about 20 days post partum before declining to adult values at weaning. These changes have been discussed in relation to diet and rumen development.

Frequency of cutting and sward production

Abstract: 1. Swards of perennial ryegrass (S 24) were grown under conditions of high fertility and were cut at intervals of (a) 3 weeks, (b) 6 weeks, (c) 3 weeks changing to 6 weeks at later points in the growing season. 2. The rate of herbage production (kg D.m./ha/day) was higher throughout the season (April to November) under the longer cutting interval. Plots which were changed from 3- to 6-weekly cutting intervals subsequently showed the same rate of production as those cut every 6 weeks throughout. Inflorescences emerged from a higher proportion of tillers after long growth periods; this could explain the higher rates of production up to July.

Leaf strength studies of pasture grasses II. Strength, cellulose content and sclerenchyma tissue proportions of eight grasses grown as single plants

Abstract: 1. Leaf strengths and cellulose contents of eight grasses grown as single spaced plants were compared over a period of 14 months. From some of the samples the proportion of sclerenchyma tissue in the leaves was compared with leaf strength. 2. The leaf strengths of individual plants were measured and the strengths of the six strongest and six weakest plants in each species compared with their cellulose contents. 3. There were significant differences between species, between seasons, and between regrowth ages within seasons in both leaf strength and cellulose content. There were also significant species × regrowth age interactions, particularly in leaf strength.

Leaf strength studies of pasture grasses: I. Apparatus, techniques and some factors affecting leaf strength

Abstract: Leaf tensile-strength measurements have been made at Grasslands Division, D.S.I.R., over several years on a number of pasture grasses (Evans, 1964; Wilson, 1965). These measurements were prompted by the work of Beaumont, Stitt & Snell (1933) and Kneebone (1961), who attempted to relate leaf tensile strength to animal production value, and Edmond (1960, 1964), who considered that the toughness of pasture species may be a factor determining their tolerance to animal treading. The following is a description of the apparatus developed for this work and of the techniques employed.

Comparison of dry and wet feeding of growing pigs

Abstract: A co-ordinated trial has been carried out at eighteen centres to compare the following amounts and methods of providing water to growing pigs: (1) water in the feed in the ratio of 2½: 1; (2) water in the feed in the ratio of 4:1; (3) dry feeding with water available separately ad lib.; (4) water in the feed in the ratio of 1½: 1 and also available separately ad lib.Pigs on dry feeding had substantially worse growth rate and feed conversion; carcass lengths were slightly smaller and eye muscles slightly wider. Fat measurements were not significantly affected.

The incorporation of the resistance of Aegilops ventricosa to Cercosporella herpotrichoides into Triticum aestivum

Abstract: The introduction of resistance to eyespot (Cercosporella herpotrichoides) from Aegilops ventricosa to Triticum aestivum is described.In the hybrids, amphiploids and in the amphiploid derivatives investigated, the eyespot resistance was apparently simply inherited. Furthermore, this character was controlled by a chromosome, or chromosomes of the D genome of Ae. ventricosa and thus could be introduced into T. aestivum by recombination.

The lipolysis and hydrogenation of lipids in the digestive tract of the sheep.

Abstract: 1. The flow of digesta in the duodenum and the changes in the lipid composition of ruminal and duodenal digesta of sheep accustomed to receiving hay and oats, hay and palm oil and hay and tallow have been studied.

The value of urea nitrate and urea phosphate as nitrogen fertilizers for grass and barley

Abstract: Urea nitrate, urea phosphate, and a mixture of urea phosphate and urea were tested as nitrogen fertilizers to find whether the presence of the anion decreases the damage urea causes to germinating seeds and seedlings and increases the efficiency of urea by preventing loss of ammonia.Urea nitrate was compared with ammonium sulphate for grass grown in pots in the glasshouse and with ammonium nitrate for permanent grassland in the field. In the glasshouse, a large dressing of urea nitrate damaged the early growth of grass in sandy-loam soil. On average of sandy-loam and clay-loam soils with a small dressing of fertilizers, grass recovered similar amounts of N from urea nitrate and ammonium sulphate; with the large dressing it recovered less from urea nitrate.In the field, 100 and 200 lb N/acre were applied to permanent grassland which was cut twice. The herbage was ‘scorched’ by the urea nitrate because its solution is very acid. Urea nitrate at 200 lb N/acre produced less dry matter containing less nitrogen than did ammonium nitrate.Urea nitrate, urea phosphate and urea phosphateurea mixture were compared with ammonium nitrate for barley and grass grown in clay-loam and sandyloam soils. Tests were made of 33, 67 and 100 lb N/acre for barley and 100, 200 and 300 lb N/acre for ryegrass; the fertilizers were applied immediately before sowing. On the light Woburn soil early growth of barley was least good with urea nitrate, which also damaged the early growth of grass.

The growth of lambs grazing on perennial ryegrass, tall fescue and cocksfoot, with and without white clover, as related to the botanical and chemical composition of the pasture and pattern of fermentation in the rumen

Abstract: 1. An experiment was conducted in which lambs grazed on pastures of cocksfoot, ryegrass and tall fescue grown with and without white clover, as well as on pastures of pure white clover.

Factors affecting the gestation length in sheep

Abstract: The data from 555 normal pregnancies during a period of 6 years in a flock of Scottish Half bred ewes were examined for relationships between gestation length and litter size, birth weight, sex, and age of ewe. A' comparison of Scottish Half bred gestation lengths was also made with those of Specklefaced Welsh ewes.

The use of ruminal ammonia and blood urea as an index of the nutritive value of protein in some food-stuffs

Abstract: 1. Nine successive trials with three adult desert rams were carried out, with the aim of using ruminal ammonia or blood urea concentration as an index of the nutritive value of the proteins in the various types of forage grown in irrigated parts of the northern Sudan. The change in the ruminal ammonia and blood urea concentration were considerably higher 3 h after feeding on leguminous forages than on the non-legumes. Among legumes, lubia and lubia hay produced the highest concentrations of both rumen ammonia and blood urea. Feeding the rams on berseem hay reduced the concentrations of ruminal ammonia and blood urea to levels below those given by feeding on fresh berseem. 3. Most of the nitrogen excretion from leguminous forages was in the form of urinary nitrogen whereas for grasses faecal nitrogen made up the bulk of the nitrogen excreted. Berseem hay gave the highest nitrogen retention, followed by the butterfly pea and fresh berseem. Lubia and lubia hay gave the lowest nitrogen retention. The desert grasses produced a negative nitrogen balance when offered to the desert rams.

Experiments on the nutrition of the dairy heifer: VI. The effect on milk production of the level of feeding during the last six months of pregnancy and the first eight weeks of lactation

Abstract: 1. Forty-five Friesian first calf heifers were used in an experiment to study the effect on milk production of two levels of feeding in the last 6 months of pregnancy and two levels of feeding in the first 8 weeks of lactation. 2. In each of two years herbage was rationed daily at different rates to two groups of pregnant heifers from late April until they calved in the autumn. The mean daily rations were 3·5 lb herbage dry matter and 2·4 lb herbage dry matter per 100 lb live weight for the two groups. The mean daily amounts consumed were 2·1 and 1·8 lb herbage dry matter per 100 lb live weight respectively. 3. The rates of gross live-weight gain during the period April to August were 2·2 and 1·7 lb/day for the two groups respectively. Estimated as the net gain of the dam alone, the rates of live-weight increase during the experimental period were 0·89 and 0·49 lb/day respectively, amounting to a mean difference in live weight after calving of 57 lb between the groups.

Field experiments on the fertilizer requirements of maincrop potatoes

Abstract: 1. Fifty-one experiments on the nitrogen, phosphate and potash requirements of maincrop potatoes were carried out in Great Britain in 1956–62. Each experiment tested four rates of each nutrient in all combinations and both total and riddled yields and quality data were obtained.2. Nitrogen requirement was influenced by previous cropping and the rainfall during the preceding winter. 50–80 lb/acre of N are recommended in mixed farming rotations depending on winter rainfall, and 120–150 lb/acre of N in arable rotations.3. Yield increases from phosphate were usually larger on soils with low citric-soluble phosphate. Nevertheless, irrespective of soil phosphate status, optimum rates of application were at least 120 lb/acre of P2O5 which was the highest rate tested in most of the experiments.

High level cereal diets for the growing/finishing pig: II The effect of cereal preparation on the performance of pigs fed diets containing high levels of maize, sorghum and barley

Abstract: (1) In a 3×2 factorial experiment sixty Large White type weaner pigs (30 hogs and 30 gilts) were individually and restrictedly fed to 200 lb live weight, six diets (as wet mashes) containing 70 % of either maize, sorghum or barley, each cereal having been processed by either crimping or grinding prior to inclusion in its respective diet. A further two groups of six litter-mate hog pigs per group were used to measured the digestibility of and the nitrogen retention from these six diets at approximately 50, 110 and 190 lb live weight. 2. Grinding gave significantly better digestibility than crimping, the ground diets having significantly higher digestible energy contents than the crimped. Between cereals the order of significant decreasing digestible energy content was from maize to sorghum to barley dietary treatments. 3. There were no significant differences between cereals in nitrogen retention. Between processing treatments grinding, in terms of g. retained per kg live weight per day, gave a significantly higher value than crimping, at 107 lb live weight.