Low Plane Of Nutrition Research Articles

An analysis of factors influencing post-natal growth and development of the muscle fibre

An analysis of factors influencing post-natal growth and development of the muscle fibre

The influence of seasonal intensity of stocking on the live-weight increase from a sward

The growth of grass varies considerably from month to month. Where stock numbers are constant, as in a dairy herd, it is difficult to use grassland efficiently by grazing alone. But where grassland is used for meat production, livestock numbers may be subject to a considerable fluctuation, and with skilful adjustment of classes of stock this fluctuation can be made to approximate to the seasonal pattern of growth in the pasture.The adjustment of stock numbers to the quantity of grass present is an art which is part of successful grazing management. Understocking will lead to an accumulation of pasture which will then have to be grazed at a more mature stage, while overstocking will result in a lower plane of nutrition for the animals. The efficiency of equating stocking intensity to the pasture available in a given period will be reflected in the progress of the individual animal (in terms of daily milk yield or live-weight gain) and in the output per acre of pasture.

The hair follicle and apocrine gland populations of Zebu (Bos indicus L.) and Shorthorn (B. taurus L.) cattle skin.

Skin samples taken with a trephine of known size from Shorthorn (Bos taurus L.) and Zebu (B. indicus L.) cattle were used to determine the density of hair follicles and apocrine glands in the skin. The repeatability of the measurement of density on the same animal was found to lie between 78 and 90 per cent. The expansion of the skin as the animal grows, and the manner in which the plane of nutrition can modify growth and so the extent of expansion, has a predominating effect on the hair follicle and apocrine gland density. There is a significant difference between ages, but for each breed the regression coefficients of log follicle number on log heart girth within age groups are not significantly different. The mean number of hair follicles per sq. cm in Zebus was 1698, in Zebu crosses 1321, and in Shorthorns on a low plane of nutrition 1064. In Shorthorns on a high plane the number was 764. All differences were statistically significant.

The influence of high and low nutritional planes on the oestrous cycle and conception rate of heifers

1. During the course of investigations on the influence of High- and Low-nutritional planes on the growth, reproduction and production of heifers, sexual activity was studied by recording oestrus data. A total of 239 observations were recorded for fourteen maiden heifers for each nutritional plane; 161 for the High-plane individuals and 78 for those on the Low plane. The investigation included four breeds, viz. Beef Shorthorn, Afrikaner, Friesian and Jersey.2. The average length of the dioestrous cycle was 20·16 days for the High-plane animals, and 20·83 days for their Low-plane counterparts, the difference of 0·67 days not being statistically significant. Breed differences were not very marked, but a tendency was revealed for the Friesians of both planes to have slightly longer cycles on an average than any other breed studied.3. The modal length of the cycle for both groups was found to be 19 days, with 95·6% of the cycles falling within the normal range of 17 to 23 days. Cycles exceeding 33 days in length were, however, excluded from these calculations.4. A tendency was revealed for the initial postpubertal cycles to be longer on an average than what is usually considered the normal length. Although the High-plane heifers settled down to a regular rhythm sooner, observations showed that differences existing between individual animals is probably of greater significance in this regard than any other factor.5. Whereas the majority of the High-plane heifers reached puberty during winter, 85·7% of the Lowplane heifers came on heat for the first time in summer. It is suggested that with the approach of favourable nutritional conditions, animals in a low condition first restore depleted body tissues before the sexual cycle returns to normal activity.6. A slight tendency was noticed for cycle length to vary with the season in the case of the High-plane animals, longer cycles being recorded in summer than in winter. On the Low plane, however, the heifers concerned invariably experienced an anoestrous condition during winter, lasting anything up to 218 days. Only after they regained the losses in live weight, was sexual activity restored as previously pointed out.7. Sexual activity was shown to be greatest in late summer with little variation over the remainder of the year under normal conditions of nutrition and management, while in the Low-plane individuals it fluctuated from complete inactivity in midwinter to a peak in summer.8. Post-partum oestrus was considerably delayed by lactation in the beef animals. The High plane heifers came on heat only after weaning their calves while the Low-plane individuals required nearly a year in addition to regain depleted body reserves before sexual activity was restored. The Low-plane dairy heifers showed a longer post-partum anoestrous period also, the difference between the two groups being 20·77 days.9. The results for the number of services required per conception demonstrated that the Low-nutritional plane caused no detrimental influence on this factor. In fact, the difference existing between the two groups studied was in favour of the Low plane animals. This is in agreement with Asdell's (1952) findings. It was shown that season had no effect on the results obtained.

Ruminal ammonia formation in relation to the protein requirement of sheep: I. Duodenal administration and heat processing as factors influencing fate of casein supplements

1. Nitrogen-balance experiments showed that casein supplements fed to hill ewes on a low plane of nutrition in the later stages of pregnancy were used very ineffectively, despite the animals' need for protein.2. In confirmation of McDonald (1948a, b, 1952) extensive conversion of casein to ammonia was found to occur in the rumen, with absorption of ammonia into the blood stream.3. Casein administered to sheep by duodenal fistual was better utilized than when administered by ruminal fistula.4. The course of dissolution in the rumen of casein in the form of tough lumps was observed by a staining procedure.5. It was found possible to process casein in a way that led to better utilization as shown by nitrogenbalance experiments. This processed casein gave less ammonia in the rumen.6. It is concluded that the formation in the rumen of ammonia from proteins may be an important factor determining their usefulness to the animal. Processing may have effects on the value of a protein for ruminants quite different from those on the value for non-ruminants. The tendency to value proteins for ruminants solely in terms of their digestibility is criticized, and it is suggested that casein has disadvantages as a ‘standard protein’ in nutrition experiments with ruminants.

Studies on piglet mortality I. Effect of low temperature and low plane of nutrition on the rectal temperature of the young pig

1. The rectal temperature of piglets was determined (a) at intervals from birth up to 18 days, (b) at the same time daily until the piglets appeared to be fully thermoregulated.2. The rectal temperature of a vigorous piglet during parturition may be as high as 104–105° F.3. During the first few minutes after birth the temperature falls to about 100° F., partly as a result of the lower temperature of the external environment and partly as a result of rapid evaporation of amniotic fluid with which the young pig is covered. The fall in temperature is greater with lighter pigs than with heavier pigs.4. The temperature falls until the young pig finds its way round to the teats and starts to suckle. This struggle and activity of suckling together with the warmth in the sow's nest causes a temporary rise in temperature. During the first rest the temperature falls again to about 100° F., but vigorous pigs have a normal temperature within 12 hr.5. Piglets deprived of milk after 5 hr. and 16 hr. suckling experienced a more or less steady fall in temperature to about 98° F. in 2–3 days, when the pigs were comatose and were killed. In the case of a pig which had suckled for 7–8 days the temperature remained more or less normal for 2 days and then declined to 95° F. during 5–6 days. The length of survival depends largely on the initial weight, i.e. on the reserves accummulated during the suckling period, and possibly on the thickness of the insulating layer of subcutaneous fat.

Fleece development and wool growth on the Romney lamb

The extent to which early environment affects wool production of Romney sheep was studied by means of measurement of skin growth, and of fibre numbers and dimensions, of lambs reared to 52 weeks on contrasting planes of nutrition.Measurement of skin growth revealed a series of gradients which generally conformed with growth and development principles. A great degree of individuality among animals in skin growth on various regions was expressed, and it was not possible to prove that plane of nutrition caused differential skin growth among regions.An initial low plane of nutrition had a retarding effect on fleece development and fibre growth, but it could not be decided whether there was a permanent effect on fibre numbers. It seems that this is of little practical importance, since a low plane of nutrition during the major part of the follicle development phase does not appear to impair subsequent unit area production, providing immediate nutrition is good.Examination of fibre attributes, and quantitative fibre growth characteristics on various regions of the body, showed a series of orderly gradients. Large differences existed between the body regions for quantitative production per unit area and this suggests a widely differing nutrient supply of various skin regions.The importance of immediate nutrition is emphasized. It appears that permanent effects of early environment on future productivity take the form of a lesser area on which wool is produced. The efficiency of the processes, apparently, is not affected.

Studies on resistance of sheep to infestation with Haemonchus contortus and Trichostrongylus spp. and on the immunological reactions of sheep exposed to infestation. VI. The influence of age and nutrition on resistance to Trichostrongylus colubriformis.

Of 10 sheep aged 3-4 years which had been born and maintained under worm-free conditions, 7 died from an initial experimental infestation with Trichostrongylus colubriformis. This mortality was in striking contrast to the results with nine-months-old sheep which had had previous experience of infestation. It demonstrated that resistance to T. colubriformis could not be ascribed to increasing age. In a group fed on a low plane of nutrition and given 40,000 or 100,000 T. colubriformis larvae, more sheep developed infestations than did similar sheep in groups given an adequate or a high-protein diet. in lambs which had been kept worm-free since birth and then dosed with 20,000 T. colubriformis larvae, infestation developed almost equally in those fed on the poor diet and those fed on the high-protein diet. The groups fed on the low plane of nutrition successfully withstood subsequent challenge doses of up to 300,000 T. colubriformis larvae. In these experiments, previous exposure to infestation apparently exercised more influence on resistance than did diet.

Effects of the plane of nutrition on growth and the development of carcass quality in lambs Part I. The effects of High and Low planes of nutrition at different ages

Effects of the plane of nutrition on growth and the development of carcass quality in lambs Part I. The effects of High and Low planes of nutrition at different ages

Effects of the plane of nutrition on growth and the development of carcass quality in lambs Part II. Effects on lambs of 30 lb. carcass weight

Effects of the plane of nutrition on growth and the development of carcass quality in lambs Part II. Effects on lambs of 30 lb. carcass weight

Seasonal changes in spermatogenesis in rams : Their relation to plane of nutrition and to vitamin A status

Observations have been made on the seminal characters, body weights, and plasma vitamin A status of rams fed on carotene-deficient diets, at higher and lower levels of food intake. Carotene supplements were provided for a number of the rams at each level of dietary intake. The seminal characters exhibited a seasonal variation, characterized by a reduction in the total number and longevity of spermatozoa during the summer months. Within this period, a temporary increase in the number of morphologically abnormal spermatozoa occurred in the rams of low plasma vitamin A status, or on the lower plane of nutrition. Plasma vitamin A levels fell more rapidly in the rams on the higher plane of nutrition than in those on the lower plane. Morphological abnormality of spermatozoa attributed to vitamin A deficiency appeared at an earlier date in the high-plane group except when rams with presumably low liver stores of vitamin A were fed on the deficient diets. Vitamin A deficiency, if sufficiently severe, resulted in the appearance of a high percentage of morphologically abnormal spermatozoa in the semen of rams on both planes of nutrition. The addition of pure carotene to the diet prevented or reduced this degree of abnormality.

The effect of supermaintenance and submaintenance diets on mature Border Leicester-Cheviot ewes

SUMMARYTen fully grown Border Leicester-Cheviot ewes were divided into two groups of five; the heavier ones being about 150 lb. live weight, and the lighter ones about 70 lb. The former were placed on a low plane of nutrition, and the latter on a high plane. As the weights changed by successive amounts of 20 lb. animals were killed and dissected, and their organs and tissues weighed.

307. The occurrence in winter of milk with a low content of solids-not-fat

Data are given which show that the solids-not-fat content of the milk produced in a certain dairying area in the early months of 1942 and 1943 was unusually low, a high proportion of the individual herds yielding milk containing less than the presumptive standard of 8·5% solids-not-fat. The freezing-point depression of this milk was normal. The solids-not-fat content showed substantial improvement in May. It is suggested that the low level of solids-not-fat was due to a low plane of nutrition of the cow.

Effects of Vitamin B1upon the Development of Some Flowering Plants

1. Vitamin B1 was added to a number of different plants in a concentration of 0.01 mg. per liter. In most of the experiments the plants received vitamin B1 in the nutrient solution once a week; however, one of the cocklebur experiments received vitamin B1 twice a week, and in one of the cosmos experiments vitamin B1 was added three times a week. 2. No visible differences were detected between the control plants and those receiving B1. No significant difference was obtained in wet weight or in the accumulation of dry matter. 3. Under neither a long nor a short photoperiod, nor at high nor low planes of nitrogen nutrition, were there detectable differences which could be ascribed to additions of vitamin B1 to the cultures. 4. Vitamin B1 had no effect upon hastening flowering, upon size or number of flowers produced, or upon color or quality of the flowers of cosmos.

Growth and development in the pig, with special reference to carcass quality characters: Part II. The influence of the plane of nutrition on growth and development

No attempt will be made to give a detailed summary of all the findings of the present experiment. It is rather our purpose to draw attention to the main principles emerging.1. The influence of extremes of high and low planes of nutrition during the first 16 weeks of post-natal life upon the growth in body proportions and in anatomical composition has been studied experimentally in six pairs of closely inbred pigs. Quantitative differences in nutrition operative from birth have resulted in an average live weight at 16 weeks of 113 lb. in the High-Plane and 37 lb. in the Low-Plane animals.2. In body proportions, the head, ears, neck, legs, and body length are penalized relatively less by inadequate nutrition than are body depth, loin, and hindquarters. Conversely, good nutrition favours most the latter characters. These effects upon body form are similarly evident i n the gross weight of the different anatomical regions involved. Low-Plane animals to a large extent retain the proportions of the juvenile and High-Plane approach the conformation of the adult

The influence of low and high planes of nutrition on the composition and synthesis of fat in the pig

THE work described in this communication deals with the determination of the component acids in the depot fats of pigs which had received controlled diets at different levels of nutrition. The primary object was to ascertain how far the quantitative proportions of the various component acids varied in relation to the feeding level of the animal. It was also found possible to make a rough quantitative comparison of the amounts of each fatty acid (a) ingested by the animal, (b) deposited in the animal in the form of fat, and therefrom to deduce the amount and nature of fat synthesized in the animal, and also to compare the rates of deposition of fat in animals which had been given different rations. An investigation has recently been in progress at the Animal Nutrition Institute of the School of Agriculture, Cambridge, designed to determine the effect of rate of growth on the proportions of the different parts and tissues in the pig. The physiological and anatomical results of this investigation are in course ofpublication by Dr C. P. McMeekan. By the courtesy ofDr J. Hammond, specimens of the back and perinephric fats, in sufficient amounts for detailed component acid analyses to be made, were placed at our disposal, together with details of the diets received by the pigs and of the weights of their fatty tissues at the time of slaughter. We are informed by Dr Hammond that the plan of feeding was as follows. Thirty pigs of unusually homogeneous (inbred) stock were fed on the same diet in different amounts. Up to the age of 16 weeks the pigs were in two groups:

MINERAL NUTRITION AND CHLOROPHYLL DEVELOPMENT IN SEEDLINGS

It was observed from class-room experiments that some seedlings, when grown in distilled water, have smaller but darker green leaves than seedlings grown in a so-called complete nutrient solution. In order to account for the apparently peculiar chlorophyll physiology involved, the writer made an analysis of the growth and chlorophyll 2 conditions of such seedlings. Wilson soy bean seedlings were used in this study. The seedlings were grown in the usual manner of conducting mineral experiments with water cultures. Knop's mineral nutrient solution of the following composition was used: Ca(NO3)2, o.8 g.; KNO3, 0.2 g.; KH2PO4, 0.2 g.; MgSO4, 0.2 g.; FeSO4, o.oo4g g., and distilled water to make i,00o cc. Distilled water is referred to as a low plane of mineral nutrition and Knop's mineral nutrient solution as a high plane of mineral nutrition. The culture solutions were renewed at the end of a week. The chlorophyll from i to IO g. samples of fresh cotyledons or fresh leaves was extracted according to the method of Schertz.3