No abstract

1. From each of two populations of White Leghorn laying hens, 6 'efficient' and 6 'inefficient' hens were used in energy metabolism studies involving indirect calorimetry with activity measurement. 2. Hens classified as efficient or inefficient with respect to residual food consumption had comparable body weight and production. 3. Efficient and inefficient hens showed similar energy metabolisability, cloacal temperature, shank dimension and egg composition. 4. However, efficient hens produced less heat; activity-related heat production accounted for 29 to 54% of the difference in total heat production between efficient and inefficient hens. 5. Plumage quality also explained some of the difference in heat production, but to a lesser extent (14 to 19%). 6. Adjustment for heat increment of production changed the heat production difference slightly (-5 to 1%). 7. What was finally left unexplained (100 - 54 - 14 + 5 = 37% to 100 - 29 - 19 - 1 = 51%) was of the same magnitude as activity-related HP and is discussed in relation to basal metabolic rate.

Effects of recombinant porcine somatotropin (rpST) on growth, lean tissue growth, feed intake, feed conversion, lean tissue feed conversion, backfat thickness and lean percentage were examined in 96 growing pigs. The experiment used barrows and gilts from the genotypes Duroc, F1 (Dutch Yorkshire x Dutch Landrace) and Pietrain. Half the pigs received 14 mg rpST i.m. twice each week starting at 60 kg; others received a placebo. Pigs had ad libitum access to a diet containing 2,162 kcal net energy and 182 g crude protein per kilogram and were slaughtered at either 100 or 140 kg live weight. From 60 to 100 and from 100 to 140 kg, live weight responses to rpST averaged as follows: daily gain, +4.5 and +19.9%; feed intake, -4.4 and +3.5%; feed conversion, -8.4 and -13.9%; backfat thickness, -13.8 and -22.8%; lean percentage, +4.4 and +8.7%; lean tissue growth rate, +8.6 and +35.8%; and lean tissue feed conversion, -13.1 and -24.9%. No gender x rpST interaction was detected. However, a genotype x treatment interaction was significant for backfat thickness at both slaughter weights, showing a higher response to rpST in Duroc than in Pietrain and F1. Growth performance was improved more by rpST in F1 and Pietrain than in Duroc, especially at higher weights, but carcass traits were improved more by rpST in Duroc. The response to rpST in lean tissue growth rate from 60 to 100 kg was highest in fatter animals (Duroc, barrows), whereas from 100 to 140 kg, response in lean tissue growth rate to rpST was highest in leaner animals (Pietrain, F1, gilts).

5, 10, 15, 20 and25"C. Feed intake was lowest at25'C. Rate of gain was maximal and feed converslon (ratio feed intake: liveweight gain) was minimal at about 20.C. At computed similar intakes of feed, rate of gain decreased with 15 g/'C below 20"C.Backfat thickness was as a mean decreased in the cold, as was lean meat to fat ratio. de 20'C le gain de poids 6tait au maximum, (3) d une tempdrature de 20.C la conversion nutritive (rapport entre la ration ing6r6e et le gain de poids) 6tait au minimum. on a corrig6 d'abord le gain de poids b la mOme ration ing6r6e montrant que la taux de croissance diminue avec une quantit6 de 15 g lorsque la temp6raturebaisse avec une degr6e. L'6paisseur du lard est diminu6 h une temp6rature plus basse. Les donn6es des autres auteurs ont d6montr6s que le rapport entre la ratron ing6r6e et le gain de poids est au minimum lorsque le porc ingbrl'govo de la quantit6 de nourriture ing6r6e ad libitum. Quelques recherches ont quand-mOme d6montr6es que les porcs selectionn6s 6lev6s aux conditions favorables Deuvent obtenrr ce minimum lorsqu'on leur donne une quantit6 de nourriture plus grande que g0zo de la quantit6 de nourriture ad libitum. fTraduit oar les auteursl

A study was conducted using 32 mature 22-kg West African Dwarf Goats to measure the effect of Trypanosoma vivax infection on energy and nitrogen metabolism. Sixteen goats were infected intravenously with 14 X 10(6) T. vivax. Sixteen control goats were sham-injected. Digestibility and metabolizability of energy and N balance were measured for each goat. Heat production and energy balances were measured per treatment group from 1 wk before infection to 6 wk after infection. Goats were fed alfalfa pellets (10% above maintenance). Treated goats had a reduced (P less than .05) packed cell volume (38 to 40% before infection vs 20 to 25% 6 wk after infection) and an increased (P less than .05) rectal temperature. Log parasitemia/ml was about 6.0 to 6.2. Parasitized goats showed increased urine creatinine excretion at wk 2 postinfection. After infection, feed intake was reduced (about 15%; P less than .05) and greater variability in intake was noted. Treated and control goats had similar N output and energy output in urine. Metabolizability of energy intake was similar at 42.7 vs 42.1% in treated vs control goats, respectively. Heat production in infected goats was increased by about 15%. Treated goats lost more weight and had a lower N balance than control goats (P less than .05). The calculated maintenance energy requirement for infected goats (464 kJ ME/kg.75) was 25% greater than for control goats (375 kJ ME/kg.75).

Summary Energy balances were compared in eight pigs (6–8 kg) fed 5% glucose or 10% D‐xylose added to a basal diet. In a carry‐over design, each pig received the glucose and 2 weeks later the xylose diet or vice versa. The basal diet consisted mainly of barley, corn, soya flour and skim milk powder. Pigs were fed 1.3 times the maintenance requirement for energy. Energy balances were measured after 4 days of adjustment to the diet and over a 7 day period. The rate of weight gain was similar between the treatments. The metabolizable energy of 10% D‐xylose was about equal to 5% glucose. The heat production was similar between treatments. This indicated that the absorbed and metabolized D‐xylose is probably utilized to the same extent as or somewhat less than glucose, with the potential of some xylose being fermented in the large intestine and absorbed as volatile fatty acids. This could contribute to the well‐being of the small pigs especially under situations of limited energy intakes. Zusammenfassung Xylose als Energiequelle in Rationen für Ferkel Zum Vergleich von Energiebilanzen erhielten acht Ferkel (6–8 kg Lebendgewicht 5% Glucose oder 10% D‐Xylose zu einer Basaldiät in einem Carry over Versuch zu einer Basaldiät. Jedes Ferkel erhielt die Glucose und zwei Wochen später Xylose vice versa. Die Basaldiät bestand hauptsächlich aus Gerste, Mais, Sojamehl und Magermilchpulver und deckte das l,3fache des Bedarfes an Energie für Erhaltung. Die Energiebilanzen wurden nach einer viertägigen Adaptationsphase an das Futter in einer siebentägigen Versuchsperiode ermittelt. Die Zunahmeraten lagen bei etwa allen Behandlungen gleich hoch. Die umsetzbare Energie von 10% D‐Xylose entsprach etwa der von 5% Glucose. Die Wärmeproduktion war bei allen Behandlungen gleich. Das deutet daraufhin, daß die absorbierte und umgesetzte D‐Xylose zum gleichen oder etwas geringerem Anteil wie Glucose genutzt werden kann, wobei ein gewisser Anteil an Xylose im Dickdarm fermentiert und als flüchtige Fettsäuren absorbiert wird. Die Verabreichung von Xylose könnte damit zum Wohlbefinden der Ferkel beitragen, vor allem bei limitierter Energieaufnahme.

Conditions (total complex of stressors) during the transport of animals vary strongly between and within transports. Adverse climatic conditions are stressors that animals have to face during transport. The thermoregulation of animals id discussed with respect to threshold values for optimal climatic conditions. These thermal thresholds depend on animal related factors and environmental conditions. The specific impact of transport conditions, such as food and water deprivation, high stocking density, high humidity and high air velocity, on thermal thresholds are described.

A study was conducted with seven groups of five to six Holstein-Friesian male calves to evaluate the effect of feeding level during 6 to 14 d of age on energy metabolism of unadapted young calves. Calves were transported at 2 to 3 d of age to their new environment. At 6 d of age measurements of heat production (HP) and ME intake started and continued over a period of 8 d. Calves were fed below (four groups) or near (three groups) the maintenance requirement (19 or 30 g of milk replacer powder.kg-.75.d-1). In contrast to ME intake, HP decreased throughout the experimental period. This decrease was larger at the low than at the high feeding level (3.1 vs .9 kcal.kg-.75.d-2; P less than .001). The relationship between HP and ME intake was estimated as HP = 91 + .318 x ME intake (kilocalories.kilogram-.75.day-1). The decrease in HP, together with the constant ME intake with time, resulted in a time-dependent relationship between HP and ME intake. Estimated basal metabolic rate and efficiency of ME utilization below maintenance decreased with time, whereas the maintenance requirement remained virtually unchanged (134 kcal.kg-.75.d-1). The influence of feeding level on energy metabolism in young calves increased with time. For at least 12 d after transportation the energy metabolism of young calves had not reached steady-state levels.