kJ Metabolizable Energy Research Articles

Untersuchungen zum Energieerhaltungsbedarf wachsender schweine verschiedenen Geschlechts bei normalen und hohen Proteingaben

Six animals each out of 12 female fattening hybrids (150 X (L X E] were given rations containing 17 or 45% crude protein resp. 4 periods of growth feeding alternated with 5 periods of maintenance feeding in the live weight range between 33 and 146 kg. The feeding level did not have an influence on the level of digestibility. From the experiments with 17% crude protein in the ration 1004 and from those with 45% crude protein 947, on average 977 kJ metabolizable energy per kg LW0.62 in the maintenance periods and 980 in the growth periods were derived as maintenance requirement of metabolizable energy. These values for maintenance requirement are by 50% higher than those in previous experiments of our work team. In contrast to expectations, energy maintenance requirement did not grow due to the increase of the protein content of the rations. The utilization of metabolizable energy for retention was 73% for rations with a normal protein content and 66% for those with a high protein content. The partial utilization of metabolizable energy for fat retention was ascertained as 83% and as 49% for protein retention by means of multiply regressive evaluation.

Relative growth of incisor arcade breadth and eating rate in cattle and sheep

ABSTRACTMaximum eating rate, rmaxin kj metabolizable energy per min, at a given body weight W kg, can be predicted in normally growing cattle when adult body weight, A kg, is known, by the formula of Taylor and Murray (1987) as rmax= 31μ0·86A0·73whereu= W/A is degree of maturity in body weight. When the pattern of normal growth is disturbed by fluctuating levels of food intake, a better prediction can be obtained in terms of incisor arcade breadth. This paper gives the allometric relationship between degree of maturity in body weight,u, and degree of maturity in incisor arcade breadth uD, fo r both cattle and sheep, asuD=u0·29.Combining this allometric relationship with that of Illius and Gordon (1987) gives the following formula for incisor arcade breadth, Du(mm), in the rth species at age,t, in relation to degree of maturity in body weight,uit, and adult body weight,Aikg): Dit= 7·8 uit0·29Ai0·36. Substituting uDand adult arcade breadth, Dadult, foruand A in the formula of Taylor and Murray (1987) gives the following more robust formula for predicting maximum eating rate, namely, rmax= 0·53u3DD2adut.

Effect of cold exposure on energy metabolism in the young pig.

Twenty-four piglets were weaned at 3 weeks of age and received 615 kJ metabolizable energy/(kg body weight X day). The temperature was reduced from 29 to 25 degrees C by 4 weeks of age. Six pigs were exposed to cold by reducing the temperature to 10 degrees C by 5 weeks of age while the other six were exposed to 23 degrees C. These two temperatures were maintained for 3 weeks. Each week the three pigs closest to the mean weight of each group were used for measurements of heat production for 23 h by open-circuit calorimetry and glucose turnover by continuous infusion of [6-3H]- and [U-14C]-glucose. The animals were sacrificed at 8 weeks of age, a sample of their intercostal muscle was used for in vitro measurement of muscle respiration, and the carcass was analyzed. There was no change in heat production, glucose turnover, and rectal temperature during the 3 weeks of cold exposure, so the data were pooled. Cold exposure increased heat production by 50%, forced mobilization of fat reserves (1000 g over the 3 weeks), and increased glucose replacement rate by 20%. The decline in rectal temperature to 37.6 from 38.8 degrees C could be regarded as a strategy to reduce energy needed to regulate body temperature. In the cold, heat production equalled metabolizable energy intake, but protein deposition was maintained at the same level as that in the pigs at the thermoneutral temperature, using the energy derived from the mobilization of body fat. The increase in Na+-K+ ATPase dependent respiration accounted for 70% of the increase in O2 consumption of muscle from cold-exposed pigs and thus is potentially an important component of cold-induced thermogenesis in the pig.

The effect of ambient temperature and activity on the daily variation in heat production of growing pigs kept in groups.

In two experiments, pigs with initial weights of 20 kg were kept in climate-controlled respiration chambers. After a 7-day adaptation period at 22-24 degrees C the temperature was reduced in 4 degrees C steps to 8 degrees C and then increased to 24 degrees C. Each temperature treatment lasted 3 days. Feed contained 12 kJ metabolizable energy per g and was given at 93 and 83 g/kg0.75 per day in experiments 1 and 2, respectively. Lower temperature increased 24 h heat production, but not 24 h activity. The mean activity periods moved from before and after feeding to after feeding, especially in the afternoon. During the afternoon, activity decreased at the lower ambient temperature, whereas metabolic rate remained constant. It is concluded that the effect of ambient temperature on metabolic rate depends on the time of day. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Characterization of post-weaning traits of Simmental and Hereford bulls and heifers

ABSTRACTPost-weaning growth, dry-matter intake, carcass characteristics, chemical composition of the 9th to 11th rib section and food conversion efficiency were evaluated for Simmental bulls (15) and heifers (18) and Hereford bulls (17) and heifers (14) from approx. 240 days of age to 470 days of age. Within each breed × sex sub-class, animals were assigned to one of three energy intake levels: (1) ad libitum, (2) 795 kJ metabolizable energy (ME) per kg0·75 per day and (3) 544 kj ME per kg0·75 per day.Simmentals tended to exhibit higher post-weaning growth rate and consumed more dry matter than Herefords. At ad libitum intakes, efficiency estimates (gain/food) were greater initially but decreased more rapidly for Herefords than for Simmentals. No differences were observed in efficiency estimates between Herefords and Simmentals fed at 795 kJ ME per kg0·75 per day and both breeds fed at this level improved in efficiency as time on test increased.Bulls tended to have greater growth rate, and consume more dry matter than heifers. At ad libitum food intake, bulls were more efficient than heifers and the decrease in efficiency of the two sexes was parallel. Heifers fed at 795 kJ ME per kg0·75 per day had a constant efficiency throughout the test while bulls improved in efficiency.

Undernutrition in sheep. The effect of supplementation with protein on protein accretion.

In a comparative-slaughter experiment, individually rationed wether lambs initially of 42 kg were given 235, 362 or 456 kJ metabolizable energy (ME)/kg live weight (LW)0.75 per d as sodium hydroxide-treated barley straw with urea (six lambs per treatment), or NaOH-treated barley straw with urea plus 125 g/d white-fish meal to give 307 or 488 kJ ME/kg LW0.75 per d (seven lambs per treatment) for 92 d. All unsupplemented lambs lost both fat and body protein. The changes in fat were -3.53, -2.75 and -1.40 (SE 0.59) kg (initial value 8.6 kg), and the changes in body protein were -0.47, -0.09 and -0.14 (SE 0.13) kg (initial value 4.9 kg) for the three unsupplemented groups respectively. When supplemented with fish meal, fat was again lost as -1.53 and -0.93 (SE 0.55) kg, but wool-free body protein was increased, and gains were 0.48 and 0.89 (SE 0.12) kg for the two supplemented groups respectively. All animals lost wool-free body energy, total changes being -150, -111, -59 and -49 and -16 MJ respectively. When corrected to an equal ME intake the supplemented lambs, when compared with the unsupplemented lambs, gained (instead of losing) body protein (P less than 0.001) and lost less fat (P less than 0.05). Wool growth did not respond to supplemental protein, but was related to ME intake with an increase of 0.78 g wool fibre for each additional MJ ME. The maintenance requirements of the unsupplemented and supplemented groups respectively were estimated by regression analysis to be 554 and 496 kJ ME/kg LW0.75 per d. The apparent utilization of ME below energy equilibrium (km) was 0.31 (SE 0.08) for the unsupplemented animals, and 0.12 (SE 0.10) for the supplemented animals, well below a km of 0.70 which current UK standards (Agricultural Research Council, 1980) would predict. Most of these differences could be reconciled if basal metabolism was assumed not to be constant. It is concluded that lambs in negative energy balance can continue lean body growth at the expense of body fat, provided sufficient dietary protein is available. It is also concluded that since the animals at the lowest ME intakes required less ME than predicted by current feeding standards, the effect was that it would have been difficult to distinguish between the apparent utilization of ME for maintenance (km) and for fattening (kf).

Studies on the protein requirements of growing cattle. Effects of differing intakes of protein and energy on growth and nitrogen metabolism in young entire males.

Forty-eight Friesian entire male cattle, with an initial live weight (LW) of 135 kg, were used in two experiments to measure the response to increasing levels of dietary protein (9-11 and 7.5-10.5 g nitrogen X 6.25/kg LW0.75) at differing energy levels (800-900 kJ metabolizable energy (ME) kg LW0.75) over 120-d periods. Digestibility and N balance measurements were also made during the experiments. The diets, which were based on barley and soya-bean meal, were individually fed twice daily. In a third experiment, similar diets were given to four similar animals fitted with intestinal cannulas, at constant energy intake but with variations in dietary protein of 7.5-13.5 g N X 6.25/kg LW0.75. Chromic oxide paper was used as a digesta marker. Positive responses in LW gain and N balance to additional protein were found in both experiments but these were significant (P less than 0.05) only in the second experiment and were associated with significant (P less than 0.01) increases in the digestibility of modified acid-detergent fibre and ME intake. Mean values, which were not significantly different between treatments, for the degradability of dietary protein in the rumen and the efficiency of microbial protein synthesis were 0.57 and 31.3 g/kg organic matter apparently digested in the rumen respectively. Corresponding values obtained by regression analysis were 0.56 and 28.2. The results in general support the Agricultural Research Council (1980) proposals and suggest that undegraded dietary protein was not limiting in these experiments but that rumen-degradable protein levels were limiting on some treatments. Regression analysis indicated that the mean response to additional protein (g LW gain/g N X 6.25) per kg LW was 0.52 in Expt 1 and 0.51 in Expt 2. These responses could be largely explained by increases in ME intakes. Measurements of duodenal amino acid flow showed marked increases in essential amino acids (EAA) across the rumen. However, EAA flows, were not significantly increased at higher N intakes suggesting that protein per se was not limiting in these experiments.

Energy maintenance requirements and energy requirement for protein retention in growing rats and broilers. 1. Energy maintenance requirements of growing rats

In 4 experiments with 3 times 3 male Wistar rats each, which received rations with different protein contents (10; 25 and 40% crude protein in the dry matter), in the growth range between approximately 65 and 180 g live weight and with an environmental temperature of 30 degrees C, a total of 226 measurings of the total metabolism were carried out on the energy level maintenance, partly also with the insertion of a fasting day. The most important results were: On the energy level maintenance with the simultaneous catabolisation of body fat there was considerable protein energy retention, which amounted to between 30 and 40% of the retention achieved in the growth periods. The energy maintenance requirement can be determined with good reproducibility (standard mean deviation: +/-6%). The average energy requirement directly measured at the feeding level maintenance of 437 kJ metabolizable energy (ME)/kg live weight 0,75.d (n=224) differs insignificantly from the average value obtained by means of multiple regression analysis from experiment periods with feeding for growth 423 kJ ME/kg live weight 0,75.d (n=437). Consequently it is not necessary to differentiate between energy requirement for maintenance and energy requirement connected correlatively with the live weight (metabolic weight of the body) under conditions of growth. Energy maintenance requirement proved to be insignificantly dependent on the amount of protein in the feed. The relative values of protein quotas of 10, 25 and 40% in the feed were 100, 101 and 103%; the expected values (derived from the efficiency of ATP synthesis in the oxidation of carbohydrates and protein) amount of 100, 104 and 109%. The problem of the thermogenous effect of protein, which is also of great importance to human nutrition urgently requires further experimental investigation. For growing rats the best adaptation of the energy maintenance over the investigated period of development is achieved if the 2/3 potence of the live weight is chosen as the expression of the metabolic body weight. With high probability this can also be transferred to the characterisation of protein metabolisation.

The effects of plane of nutrition and environmental temperature on the energy metabolism of the growing pig

1. The heat losses and energy balances of thirty-eight individually housed pigs (initial body-weights 21--38 kg) were measured continuously for periods of 14 d when they were maintained at environmental temperatures of 10, 15, 20, 25 or 30 degrees. At each temperature four levels of feeding were given approximating to once, twice and three times the maintenance energy intake and the ad lib. level. The minimal maintenance energy requirement (M) was calculated to be 440 kJ metabolizable energy (ME)/kg0.75 per d at 25 degrees. 2. ME intake at the ad lib. level decreased from 1965 kJ/kg0.75 per d at 10 degrees to 1202 at 30 degrees. 3. Heat loss calculated from multiple regression analysis decreased to minimum levels between 20 and 25 degrees; 30 degrees was within the hyperthermic zone at each plane of nutrition. 4. The partition of heat loss into its sensible and evaporative components showed that evaporation increased from 25% at 10 degrees to 78% at 30 degrees. 5. Critical temperature was dependent upon food intake and decreased from 23.1 degrees at M to 20.7 degrees at 2M, 18.0 degrees at 3M and 16.7 degrees at 4M. 6. The extra food required to meet extra thermoregulatory heat production per 1 degrees below the effective critical temperature was 0.65 g/kg body-weight per d.

The assessment of thermal environment in relation to pig production

The thermal environment comprises factors which influence an animal's heat exchange through the channels of evaporation, radiation, convection and conduction. The air temperature is often used by itself as an assessment of the thermal environment, but air temperature by itself is inadequate for this purpose unless conditions are standardized with air and mean radiant temperatures equal to each other, free convection, and an insulated floor. Farming environments are not standardized, but climatic investigations allow an equivalent standardized environmental temperature ( ESET) to be calculated for a given situation. Information on energy retention and heat loss in the pig has been derived from experiments under standardized conditions. ESET can be used to transfer the results of these experiments to pig farming conditions, and to determine for different types of housing the air temperatures equivalent to the effective critical temperatures found under standardized conditions. Experimental results can then be used to estimate the production losses which occur when ESET falls below the critical temperature, and the decision can be taken on increasing feed or improving heating or nsulation. For pigs in gorups in the body weight range 20–50 kg, the calculated air temperatures for maximum productivity range from 14°C in an insulated house free from draughts to 22°C in an uninsulated house with draughts in winter. Below these temperatures the animals' heat losses increase by approximately 4 kJ/°C per kg per day. For a feed with 1 g  12 kJ metabolizable energy, the increased heat loss leads to an increased feed requirement of 0.3 g/°C per kg per day for maintaining maximum production.