Showing papers by "Rowett Research Institute published in 1974"

Heavy metal toxicities.

Abstract: Several reviews have been published recently on the toxicity of heavy metals, but few of these have made any reference to the influence of the nutritional state of animals upon their tolerance of heavy metals. Furthermore, the clinical and metabolic changes occurring as a consequence of increased dietary intake of heavy metals are extremely dependent on factors such as the mineral composition of the diet and nature of the protein source. These aspects will be given particular attention in this review.

Anaerobic digestion of organic matter

Abstract: (1974). Anaerobic digestion of organic matter. C R C Critical Reviews in Environmental Control: Vol. 4, No. 1-4, pp. 131-191.

Heat loss and energy retention during growth in congenitally obese and lean rats.

Abstract: 1. Heat losses associated with the utilization of metabolizable energy for synthesis of protein and of fat during growth were studied in Zucker rats selected for normal leanness or congenital obesity.2. Measurements of energy and nitrogen balance were made on groups of four lean and four fat rats offered food ad lib. and kept at 22°. Balance trials were also conducted on groups of fat or lean rats offered restricted amounts of food at two levels and kept at 22° or 28°. The medium rations offered to fat and lean rats were the same. The energy and N contents of fat and lean rats were determined by carcass analysis at 35 d and at about 90 d of age.3. At ad lib. intake, fat rats ate 38% more than lean rats. Heat losses and N balance were similar. When fat and lean rats were pair-fed, heat loss and N retention were lower in fat rats. Absolute values and changes during growth of heat loss (kJ/rat per 24 h) were closely correlated with values obtained for N balance.4. Carcass analysis showed that energy retention in protein was, on average, 75% in lean rats but only 14% in fat rats. Estimates of energy retention from slaughter experiments and balance trials agreed well, but marked discrepancies existed between the different estimates of N retention.5. The net efficiencies of utilization of metabolizable energy for growth in lean and fat rats were 0.485 and 0.614 respectively. The energetic efficiencies of net protein synthesis and net fat synthesis were estimated to be 43 and 65% respectively.6. The interactions between appetite, growth and activity in the development of obesity in the Zucker rat are discussed.

Effect of processing of cereals on rumen fermentation, digestibility, rumination time, and firmness of subcutaneous fat in lambs.

Abstract: 1. The effects of processing cereals on aspects of rumen metabolism, physiology and pathology were investigated in five experiments with lambs. Three experiments studied the effects of diets containing loose whole, pelleted whole or pelleted rolled barley on rumen volatile fatty acid ratios, rumen pH and digestibility. In a 4th experiment the effects, on the same measurements, of pelleting whole barley, maize, oats or wheat compared to feeding the whole grains in the loose form were studied. The firmness of subcutaneous fat was measured in two of these experiments when injections of cyanocobalamin or hydroxycobalamin were given and in one experiment when the diets were supplemented with two levels of cobalt. In a 5th experiment, the effect on rumination time of pelleting whole barley compared to feeding loose whole grain was assessed.2. When the diet contained whole barley in a loose mix and also when it contained whole maize, oats or wheat, the proportion of acetic acid in the rumen fluid was significantly increased and that of propionic acid decreased in comparison with the proportions observed when the pelleted diets were offered.3. The pH of the rumen liquor was not significantly changed by feeding pellets based on rolled or whole barley, but when barley, maize, oats or wheat was given in loose form, there was an increase in the pH by about 1 unit in comparison with the pelleted diets. This increase in pH was, for all cereals, associated with complete elimination of ruminitis which, except for the oat diet, was always apparent with the pelleted feeds.4. In general the digestibilities were not affected greatly by processing and in two experiments there were no significant differences. In one experiment pelleted whole barley was better digested than pelleted rolled barley. In another experiment the digestibility of barley was slightly greater when it was fed whole and loose compared to pelleted, while the digestibility of whole wheat was less than that of pelleted wheat. The mean digestibilities of organic matter for barley, maize, oats and wheat were 0.791, 0.832, 0.687 and 0.846 respectively.5. Neither injections of vitamin B12 nor cobalt supplementation of the diet had any effect on the firmness of subcutaneous fat. Feeding diets containing loose whole barley increased the firmness of the subcutaneous fat, and this was associated with a decrease in the proportion of propionic acid in the rumen fluid.6. The feeding of loose whole barley instead of pelleted whole barley caused an increase in time of rumination from 3.6 to 6.6 h/24 h.

Hepatic copper- and zinc-binding proteins in ruminants. 2. Relationship between Cu and Zn concentrations and the occurrence of a metallothionein-like fraction.

Abstract: 1. A study has been made by gel-filtration techniques of the soluble copper- and zinc-binding proteins in livers from calves and sheep of widely differing Cu and Zn status. 2. Cu and Zn generally occurred together in three main fractions, with approximate molecular weights of > 75000, 35000 and 12000, and Zn also in one other fraction with molecular weight about 65000. The distribution of the metals between these fractions was variable and dependent on both the Cu and Zn status of the animals. 3. Zn was usually absent from the low-molecular-weight fraction in Zn-deficient or high-Cu livers, with Cu also being absent in the former instance. 4. The fraction with molecular weight of 35000 was tentatively identified as hepatocuprein. It generally accounted for only 4% of the total hepatic Cu except in Cu-deficient livers. 5. The possible relationship of these findings to the mutual antagonism between Cu and Zn is discussed.

The determinatio of tryptophan in purified proteins and in feeding-stuffs

Abstract: 1. A method was developed for the estimation of tryptophan in purified proteins or in feeding-stuffs. Samples were hydrolysed by autoclaving them with barium hydroxide in polypropylene flasks or tubes. Excess Ba was precipitated as the hydroxide by cooling, and hydrogen sulphide formed during hydrolysis was removed under reduced pressure. Tryptophan was assayed colorimetrically with dimethylaminobenzaldehyde by comparison with tryptophan standards carried through the complete procedure.2. The method was applied to purified proteins, to analysed materials and to a wide range of samples. Results agreed fairly well with published values for purified proteins, though rather less well for the samples analysed by other workers. Reasons are discussed. The samples examined gave results in the expected range.

Hepatic copper-and zinc-binding proteins in ruminants. 1. Distribution of Cu and Zn among soluble proteins of livers of varying Cu and Zn content.

Abstract: 1. A metal-binding fraction with a molecular weight of about 12000 in calf and sheep liver has been characterized as a metallothionein-like protein. 2. The combined concentrations of copper and zinc in the fraction (as μg/g liver) are a direct function of liver Zn concentration. 3. The relative proportions of Cu and Zn in the fraction are dependent on the Cu: Zn ratio in the liver. 4. These findings may be relevant to the mutual interaction between Cu and Zn.

Prediction of the Energy Requirements for Growth in Beef Cattle 1. The irrelevance of fasting metabolism

Abstract: 1. According to the Agricultural Research Council (1965) energy retention in cattle is predicted from metabolizable energy (ME) intake, the net availabilities of ME for maintenance (km) and for fattening (kf) and measurements made of fasting metabolism (F). The present experiments were designed to examine the validity of the use of F as a basis from which to predict energy retention.2. Four British Friesian and four Aberdeen Angus steers were fed, from weaning to slaughter at about 450 kg, a barley-based, pelleted diet at two levels calculated to yield overall efficiencies of retention of ME of 20% and 10% respectively. Successive measurements were made of the energy balance of each animal at intervals of 4 to 8 weeks.3. The metabolizability of the diet was measured for both sheep and cattle. In both species metabolizability was greater at the higher level of feeding. In sheep kf measured directly or estimated from metabolizability was 0·61.4. Measured values for F in cattle agreed closely with values given by the Agricultural Research Council.5. Basal metabolism in the growing animal (F') was predicted by extrapolation to zero intake of measurements made on animals in positive energy balance. Log F' during growth was proportional to log body weight0·73. Expressed in terms of the usual exponent of metabolic body size, F' was about 440 kJ/kg0·75 per 24 hr throughout growth. There were no major differences in F' attributable to breed or to level of food intake.6. The results indicate that F is not a good basis from which to predict energy retention in steers.

The effect of dietary crude protein concentration and time of weaning on milk production and body-weight change in the ewe

Abstract: Twenty-seven North Country Cheviot ewes, each carrying twin foetuses and having a mean body weight at 6 weeks prior to parturition of 81 kg were individually penned and offered a constant daily intake of 16·75 MJ metabolizable energy during the last 6 weeks of gestation At parturition the ewes were allocated to one of three dried grass/concentrate diets containing (1) 10·3, (2) 13·6 or (3) 16·9 % crude protein (CP) and 10 MJ metabolizable energy (ME) per kg The mean daily CP intakes for diets 1 to 3 were 273, 340 and 415 g respectively and the mean daily ME intake was 25 MJ Within each level of dietary CP intake the lambs were weaned at either 25, 35 or 41 days of ageThere were no significant diet × stage of weaning interactions in milk yield or ewe body-weight change during lactation The mean daily levels of milk production were 2·4, 2·9 and 3·1 kg for diets 1 to 3 respectively The corresponding values for ewe body-weight loss were 118, 170 and 265 g per day When the diet contained 13·8% CP the incremental increase in milk production per unit increase in protein intake was 4·2 g/g This gave an incremental increase in lamb growth rate of 0·79 g/g and was equivalent to the associated incremental increase in ewe body-weight lossA reduction in the concentration of CP in the ewes' diet when the lambs are 3 weeks of age may be a useful practical procedure for decreasing milk production and for reducing the body-weight loss of the ewe in a frequent breeding system

The utilization of gelled maize starch in the small intestine of sheep.

Abstract: 1. A solution of gelled maize starch and Cr-EDTA was continuously infused for 4 weeks via the abomasum into sheep of different ages. The proportions of infused α-glucoside passing the terminal ileum as glucan (ethanol-precipitable α-glucoside), dextrins (ethanol-soluble glucose polymers) and glucose, and the glucan and over-all α-glucoside disappearances in the small intestine were determined. Ethanol-soluble α-glucoside compounds in ileal digesta were further separated by paper chromatography. 2. Glucan was efficiently degraded, since little reached the terminal ileum. Most of the α-glucoside in ileal digesta consisted of glucose and dextrins (mainly short chain length oligosaccharides), suggesting that α-amylase activity was not limiting over-all starch utilization. 3. No adaptation of intestinal starch utilization was evident except that the proportion of infused α-glucoside passing the terminal ileum as glucose decreased with time. 4. A negative correlation existed between the pH and the total α-glucoside content of the ileal digesta, possibly relating to changes in the microbial activity. 5. The advantages and disadvantages of feeding with starch so as to by-pass rumen fermentation are discussed.

Cereal processing and food utilization by sheep 2. A note on the effect of feeding unprocessed barley, maize, oats and wheat on food utilization by early-weaned lambs

Abstract: An experiment was carried out with 64 lambs to determine the digestibility and efficiency of food utilization of barley, maize, oats and wheat when they were offered whole and loose, or roughly ground and pelleted. Apparent digestibilities of the organic matter (%) for the four cereals in the order given above were 81·1, 84·3, 69·9 and 82·7 for the whole and 77·2, 82·1, 67·5 and 86·6 for the ground and pelleted grains. The corresponding live-weight gains (g/day) were 340, 345, 241 and 303, and 347, 346, 238 and 323. The corresponding conversions of dry matter (kg) to live-weight gain (kg), over the growth period from 15 to 35 kg weight, were 2·75, 2·52, 3·07 and 2·97 and 2·79, 2·62, 3·33 and 2·56.

Effect of processing of dietary barley and of supplementary cobalt and cyanocobalamin on the fatty acid composition of lamb triglycerides, with special reference to branched-chain components.

Abstract: 1. The possibility that, when lambs are fed on barley-rich diets, vitamin B 12 might limit hepatic utilization of propionate and result in the formation of branched-chain fatty acids was investigated with thirty-six animals allocated to twelve treatments according to a 3 × 2 × 2 factorial design. 2. From 13 kg live weight to slaughter at 35 kg the lambs were given diets containing barley in one of three physical forms, and one of two levels of cobalt (0.1 and 0.9 mg/kg diet). In addition, half the lambs received twice-weekly injections of cyanocobalamin (40 μg/kg body-weight). 3. The fatty acid composition of triglycerides from subcutaneous and perinephric adipose tissue was determined at slaughter. 4. Neither additional dietary Co nor the administration of cyanocobalamin (alone or in combination with additional Co) influenced the proportions of branched-chain acids in the triglycerides. The possibility is discussed that the ability of the lamb to respond to the increased supply of propionate which is provided by a high-barley diet is not restricted by the availability of cyanocobalamin, but by hepatic capacity to utilize it for the production of methylmalonyl-CoA mutase ( EC 5.4.99.2). 5. Regardless of diet, subcutaneous triglycerides contained greater proportions of propionate-derived fatty acids than did perinephric triglycerides which contained greater proportions of exogenously-derived C 18 unsaturated acids. Lambs given whole barley in loose mix produced triglycerides containing relatively less odd-numbered n -acids and branched-chain acids than did lambs fed on either of two pelleted diets containing rolled or whole barley.

Recent studies of antagonistic interactions in the aetiology of trace element deficiency and excess.

Abstract: I n recent years, evidence from both field and laboratory studies has shown that a number of trace element deficiencies arise or can be induced as a result of biological interactions between these nutrients. Similarly, some of the toxic effects resulting from the ingestion of excessive amounts of both essential and non-essential elements may be ascribed to interactions with biological processes directly or indirectly involving other trace elements. Some appreciation of the range and complexity of the trace element interactions that may occur under practical situations can be obtained from Fig. I. In this paper a positive interaction is defined as one in which the presence of one element is essential for the normal metabolic action of a second element and a negative interaction as one in which the presence of an excess of one (or more) element antagonizes the normal actions of a second. It is clear that a complete discussion of all these complex interactions is beyond the scope of this review and thus a selected few will be considered in order to highlight some of the important features characteristic of these interactions.

Desaturation of long-chain fatty acids by tissue preparations of the sheep, rat and chicken

Abstract: 1. 1. Desaturase activity of microsomal preparations from sheep liver was low compared with that of similar preparations from rat and chicken liver; highest activity was found in microsomes from chicken liver. Desaturase activity of microsomes from perinephric adipose tissue relative to that of microsomes from liver was markedly higher in sheep compared with rat and chicken; lowest activity was found in the chicken. 2. 2. Microsomal desaturase activity of the jejunal mucosa, liver and perinephric and subcutaneous adipose tissue of the sheep increased in that order. 3. 3. Desaturase activity of microsomes from lactating mammary tissue of the sheep was of the same order as that found in microsomes from perinephric and subcutaneous adipose tissue. Weaning the lambs resulted in decreased desaturase activity in microsomes from the mammary tissue of the respective ewes. 4. 4. Microsomes from sheep liver, in the presence of l -glycerol 3-phosphate and particle-free supernatant, incorporated [1-14C]-stearate mainly into phospholipids. Similar preparations from the chicken incorporated [1-14C]-stearate mainly into triacylglycerol, whereas in preparations from the rat significant incorporation into phospholipid and triacylglycerol occurred. 5. 5. Liver slices from lactating ewes incorporated [1-14C]-acetate mainly into phospholipids, whereas incorporation by slices of lactating mammary tissue was largely into triacylglycerols. Incorporation of [1-14C]-stearate into slices of liver and mamary tissue was low, but followed a similar pattern to that found for acetate incorporation. 6. 6. A higher ratio of mono-unsaturated to saturated fatty acids was observed when tissue preprations were incubated with [1-14C]-acetate compared with [1-14C]-stearate. 7. 7. The possibility is discussed that a preferential desaturation of endogenously synthesized fatty acids takes place.

Toxicity of kidney beans (Phaseolus vulgaris L). to conventional and gnotobiotic rats.

Abstract: Raw and irradiated diets containing kidney beans as the sole source of protein and providing 10% crude protein (N × 6.25) produced severe weight loss, followed in some cases by death, in conventional hooded rats. The mean weight loss of the surviving rats exceeded the mean weight loss of control animals fed a non-protein diet. When fed to gnotobiotic rats the irradiated bean diet produced a slight gain in the mean weight of the animals over the 10 day experimental period and a net protein utilisation (n.p.u.) of 16. This figure fell far short of the value of 52 estimated from the chemical score. Diets containing beans + casein, each providing 5% crude protein gave n.p.u. value of 53 in gnotobiotic rats, a figure which approached that anticipated from the chemical score of the diet (=61). In conventional rats the same diet gave n.p.u. values of 14 (non-irradiated) and 16 (irradiated).

Effect of environmental temperature on the degree of unsaturation of depot fats of pigs given different amounts of food.

Abstract: 1 Measurements were made of the iodine value (IV) of fat from seven sites on pigs which had been kept at 5, 13 or 23 oC during their growth from 20 to 90 kg. At each temperature the pigs were given one of three levels of daily food intake. 2 The IV of the outer back fat exceeded that of the inner by 7.7 units at the shoulder, 6.8 units at the midback and 2.4 units at the rump. 3 Increasing daily food intake significantly depressed the IV of fat only at the shoulder sites. 4 The IV of fat at all sites fell with increasing temperature by an amount ranging from 0.22 units per 1 oC at the midback to 0.55 units per 1 oC in the inner shoulder fat. The IV of perinephric fat fell by 0.39 units per 1 oC increase in temperature; that this fat was thus affected suggests that the effect of environmental temperature on fat composition is not conditioned by its effect on local tissue temperature. 5 It was calculated that these effects arose largely by changes in the proportions of fatty acids synthesized de novo; the exogenous fat consumed could have made only a small contribution.

Digestion of concentrates in sheep. 5. The effect of adding fish meal and urea together to cereal diets on protein digestion and utilization by young sheep.

Abstract: 1. In one experiment according to a latin square design five sheep with fistulas in the abomasum and terminal ileum were given diets based on barley. Five diets were compared, one without protein supplementation, two with different levels of fish meal and two with combinations of fish meal and urea. 2. The amount of non-ammonia crude protein passing through the abomasum and removed from the small intestine increased linearly with fish-meal supplementation but the only effect of supplementation with urea was to increase the crude protein removed before the abomasum. It was concluded that urea did not appear to have a sparing effect on the degradation of dietary protein. 3. Seventy-eight lambs were used in a second experiment. They were given thirteen diets made up from a basal barley diet and different combinations of fish meal and urea. 4. Digestibility of organic matter and efficiency of food conversion increased with each level of fish-meal supplementation. The effects of urea supplementation on organic matter digestibility and efficiency of food conversion depended upon the level of fish meal in the diet and at the highest level of fish-meal supplementation there were no effects. 5. The maximum digestibility of organic matter (about 820 g/kg) could be achieved both with urea alone and fish meal alone and was attained at a lower level of nitrogen in the diet with urea. In contrast, the maximum food conversion efficiency that could be achieved with a fish-meal supplement was much greater than could be obtained with a supplement of urea alone.

Protein quality of feeding-stuffs. 6. Comparisons of the results of collaborative biological assays for amino acids with those of other methods.

Abstract: 1. Twelve commercial samples of high-protein feeding-stuffs, six of them fish meals, were used for a study of the reproducibility of chemical, microbiological and biological assay values for individual amino acids. Comparisons were also made of results obtained by different methods for the same amino acid.2. For lysine there was quite good agreement between the results from the different laboratory tests for ‘available’ lysine. The values for ‘total’ lysine were, on average, 10 % higher than those for ‘available’ lysine.3. For methionine the correlations between the chick assay and each of the laboratory tests were similar.4. The results from the ‘total protein efficiency’ test of over-all protein quality, using chicks, showed a close correlation with the results of lysine or methionine assays according to which of the two amino acids was most deficient.5. The results with tryptophan were difficult to interpret and no recommendations could be made as to procedures suitable for general use.6. Although most of the present samples proved to be of good quality, only screening of a much larger number of samples will reveal to what extent commercial protein concentrates of low availability are still liable to come onto the market.

A method of including urea in whole grains

Abstract: A method of including urea into whole grains is described. The whole grains were found to absorb completely a saturated solution of urea.The method gave the different cereals examined (barley, oats, wheat and maize) a homogeneouis distribution of urea and increased the voluntary intake of whole grains by lambs. The evolution of NH3 in the rumen liquor was slightly slower when urea was absorbed into the grains than when it was included as urea crystals. The N content in the urea-treated grain was not changed after 6 months of storage.

The in vitro metabolism of propionate and glucose by the rumen epithelium

Abstract: 1. 1. l -Lactate and pyruvate were formed when cattle rumen papillae were incubated in vitro with added propionate, valerate or glucose. 2. 2. Butyrate inhibited the formation of pyruvate from propionate, while ammonium chloride inhibited l -lactate formation but stimulated pyruvate formation. 3. 3. The presence of glucose together with propionate resulted in a synergistic increase in l -lactate and pyruvate formation. 4. 4. The formation of l -lactate and pyruvate from added propionate and the activities of some enzymes involved in this conversion were similar using epithelium taken from four areas of the sheep rumen.

Studies on the Appearance of a Copper-Binding Protein in Rat Liver

Abstract: Studies on metalloproteins in ruminant livers showed the relationship between the total amount of zinc and copper present in a metallothionein-like fraction (designated fraction 111) and the zinc content of livers can be described by the equation y = 0.74~-0.25 (s.E. of regression coefficient = h0.04, P

Fatty acid composition and desaturase activity of tissues of the congenitally obese Zucker rat.

Abstract: 1. 1. The proportions of the major component fatty acids of triacylglycerols from subcutaneous and perinephric adipose tissue and the C 16 and C 18 fatty acids of liver lipids were determined in congenitally obese (Zucker) rats, their lean littermates and in non-obese, hooded Lister rats of comparable ages. Relatively more 16:0, 16:1 and 18:1 and less 18:2 were found in liver lipids and adipose tissue triaglycedrols from congenitally obese rats than in their lean littermates. The proportions of the major fatty acids in tissues from the hooded Lister rats resembled those in tissues from lean Zucker rats of the same age, except that the proportion of 16:1 in adipose tissue was of the same order as that found in obese Zucker rats. 2. 2. Monodesaturation of stearate and palmitate was five-sevenfold greater in liver preparations from congenitally obese rats than it was in similar prepara- tions from their lean littermates. In liver preparations from hooded Lister rats of comparable age, monodesaturation was intermediate between that found in obese and lean Zucker rats; hepatic monodesaturation in younger hooded Lister rats resembled that found in obese Zucker rats. 3. 3. Incorporation of [ 14 C] activity of stearate and palmitate into various lipid classes by liver homogenates (in the presence of spl-glycerol 3-phosphate) was determined for the three types of rat. Congenitally obese rats incorporated more activity into triacylglycerols and less into a fraction containing monoacyglycerols and phospholipids than did either lean littermates or hooded Lister rats. 4. 4. The results are discussed in relation to increased endogenous synthesis of fatty acids in the tissues of the congenitally obese rats.

The detection of trace element deficiency and excess in man and farm animals.

Abstract: The certainty and speed with which a disorder arising from deficiency or excess of a dietary component can be recognized depends greatly upon the clarity with which the clinical consequences of this disorder have been characterized in experimental studies. Among the many disorders attributable to deficiency or excess of the trace elements only one, ‘swayback’ in the copper-deficient lamb, can be clearly recognized by its gross signs. With the others the signs are insufficiently specific to achieve a satisfactory diagnosis by consideration of a single gross lesion. In these circumstances, progress towards identification of the disorder must then be achieved by more detailed consideration of the variety of clinical and metabolic lesions, by determination of the trace element content of animal tissues obtained by biopsy or post mortem or, finally, by determination of the trace element content of the diet or other vehicle whereby these elements gain access to the subject. The purpose of this paper is to examine some of these supporting diagnostic procedures and particularly to consider their limitations, where these may originate from inadequacies in experimental studies of the clinical and metabolic consequences of trace element deficiency and excess in animals.