Naked oats: metabolisable energy yield from a range of varieties in broilers, cockerels and turkeys.

1. Naked oats belong to the same species as 'common oats', Avena sativa, but have a non-lignified husk which readily becomes detached during harvesting. The absence of the indigestible husk can be predicted to give an increased metabolisable energy (ME) content for poultry. 2. Measurements of true metabolisable energy (TME(N)) were performed on 3-week-old broiler chicks (Cobb males), adult cockerels (ISA Brown, greater than one year old) and 7-week-old turkeys (BUT T8 males). The measurements were repeated in 2000, 2001 and 2002, with some measurements on a subset of varieties in 2004. 3. High-oil naked oat lines yielded 12% more energy (TME(N)) than wheat. Naked oats, excluding the experimental high-oil lines, yielded 8.5% more energy than simultaneously assayed wheat samples. 4. In samples from the 2004 harvest, conventional oats gave TME(N) values about 13% lower than those of wheat. 5. The addition of beta-glucanase produced an increase of about 4% in the apparent metabolisable energy (AME) of oats for broiler chickens. This effect was associated with a 70% decrease in the jejunal viscosity of broilers receiving a 500 g/kg naked-oat diet. 6. The oil content of naked oats was about 5 times greater than that of wheat, with the high-oil lines rising to more than 6 times greater. Naked oats had a lower starch content than wheat but not sufficiently lower to negate the energy benefits of the higher oil content. The crude protein (CP) contents of naked oats were similar to those of wheat, with the high-oil varieties tending to be higher in CP also.

Food intake, growth rate, food conversion and food choice in broilers fed on diets high in rapeseed meal and pea meal, with observations on sensory evaluation of the resulting poultry meat.

1. Experiments were done to measure the effects of 100 and 200 g/kg of either pea meal or low glucosinolate, low erucic acid rapeseed meal on food intake and growth, food choice and meat organoleptic quality in broiler chickens. 2. The test diets were formulated to be iso-energetic and iso-nitrogenous with a soy-wheat control diet. In all diets, lysine was fixed at 11.0 g/kg and all other indispensable amino acids were present in excess of requirements. 3. Food intake was little affected by the inclusion of 100 g/kg of pea meal in the diet but 200 g/kg of peas caused a decrease. Rapeseed produced a decrease in food intake at both dietary concentrations. 4. Weight gain was similarly affected, but food conversion from d 0 to d 42 was little affected by the inclusion of either peas or rapeseed. 5. Absolute breast muscle weight was affected by diet but there was no significant difference in breast weight as a proportion of total body weight. 6. From d 7 onwards, selection against the pea-containing diet approached statistical significance. Between d 7 and d 14, birds ate almost twice as much of the control as of the pea-containing diet. Birds offered a rapeseed meal diet ate similar amounts of that and the control diet. 7. The breast meat from birds given 200 g rapeseed/kg was the only meat identified as different but no strong aversion was expressed by the tasting panel.

Variation in temperature increases the cost of living in birds.

The effect of temperature variability on laying birds was studied experimentally, using Japanese quail. Two aspects of temperature variability were investigated: the effects of regular daily variation in temperature, and of a sudden change in temperature. Both of these may become more common as a consequence of climate change. These manipulations were carried out at two levels of food supply. Energy expenditure increased with higher daily temperature variation, and also after a sudden change in temperature, taking several days to settle to a constant level. Manipulating daily temperature variation also resulted in smaller eggs being laid under more variable temperatures, when food quality was also low. The results demonstrate that day-to-day variation in temperature, as well as mean temperature, affects energy expenditure, which can have consequences for egg production.

Different concentrations and sources of dietary fibre may improve the welfare of female broiler breeders.

1. Broiler breeder females were fed restricted allocations of food to meet target body weights. They were fed on a standard wheat-soy ration or on one of three series of rations containing 50, 100 or 200 g/kg of ground oat hulls, ground unmolassed sugar beet pulp or sunflower meal. Changes in behaviour and heterophil-lymphocyte ratio (HLR) were measured at 5, 10 and 15 weeks of age. 2. Body weight at 15 weeks of age decreased in a linear manner with increasing concentrations of the experimental ingredients. 3. Decreased spot pecking was observed in birds fed on the rations containing 50 g/kg of sugar beet pulp and 200 g/kg of oat hulls. 4. The HLR was higher in birds fed on the control diet and diets containing 50 g/kg of the high fibre ingredients. 5. Rations containing sugar beet pulp were associated with higher water contents in the gastrointestinal tract and it is proposed that this improved satiety and welfare.

Effects of ambient temperature and restricted feeding on the growth of feathers in growing turkeys.

1. Male turkeys were reared to 6 weeks of age at 15 degrees C and 26 degrees C and fed ad libitum or restricted to 0.5 of the body weight of birds fed ad libitum. Basal metabolic rate was determined by indirect calorimetry at an ambient temperature of 20 degrees C. 2. Turkeys at 15 degrees C were lighter than those kept at 26 degrees C. Feather lengths and weight were similar in both groups. Fasting heat production corrected for both metabolic body size and activity was greater in turkeys reared at 15 degrees C than those at 26 degrees C. 3. Cranial breast feathers were significantly longer in restricted birds than in those fed ad libitum in contrast to a proportional decrease in the lengths of other feathers of 0.1 to 0.3. Feather weight as a proportion of body weight was 0.072 in restricted turkeys compared with 0.046 in birds fed ad libitum. There was no difference in basal metabolic rate between ad libitum and restricted turkeys. 4. It was concluded that feather growth was maintained in preference to body and muscle growth and that rearing birds at 15 degrees C did not improve breast feather cover. It is suggested that the growth of breast feathers in turkeys fed ad libitum is impaired.

Development of pecking damage in layer pullets in relation to dietary protein source.

1. In recent years, the UK egg industry has become increasingly dependent on plant protein sources, in particular soyabean meal, and it has been suggested that this trend (and/or the concomitant absence of animal protein in layer diets) might be causally related to increased feather pecking and cannibalism. 2. This study examined the development of pecking damage in relation to dietary protein source, by rearing 12 groups of 12 layer pullets to 24 weeks of age on diets based on 'animal' (fishmeal) or 'plant' (soyabean meal) protein. 3. Damaging pecking began at 6 weeks of age, in three groups (one plant and two animal). Injurious pecking began at 18 weeks of age, and affected four groups (two plant and two animal). 4. Greater numbers of vigorous pecks/pulls were observed in plant protein groups throughout the experiment, although they were significantly higher only between 13 to 16 weeks of age. Pecking damage scores did not differ between treatments. 5. Dietary protein source did not affect plasma oestradiol, progesterone or egg production. 6. These results do not support the notion that inclusion of fishmeal in laying hen diets prevents or alleviates feather pecking and cannibalism.

True metabolisable energy, heat increment and net energy values of two high fibre foodstuffs in cockerels.

1. The yields of true metabolisable energy (TME) and net energy (NE) from chaya leaf meal and wheatfeed were mcasured in tube-fed cockerels. 2. TME, 5.76 MJ/kg, from chava leaf meal was lower than from wheatfeed, 8.39 MJ/kg. The total heat increment attributable to the feeding of chaya leaf meal was 1-7 times greater than that of wheatfeed. 3. The net efficiency of utilisation of ME (k) from chaya leaf meal was 0.64, while that from wheatfeed was 0.86. The role of different chemical composition, especially the high fibre content of the materials, is discussed. 4. The metabolisable energy and net energy values derived from chava leaf meal represented 0.34 and 0.23 respectively of its gross energy content. The combination of lower TME and lower net efficiency of utilisation led to chaya having a NE value, 3.86 MJ/kg, which was only 0.53 that of wheatfeed.

Effects of ambient temperature on heat increment of feeding and energy retention in growing broilers maintained at different food intakes.

Zero-activity heat production (HP), body temperature (Tb) and energy retention were measured in growing broilers maintained at 5 ambient temperatures (Ta) (14 degrees , 17 degrees , 22 degrees , 27 degrees and 32 degrees C) and at 5 feeding rates (ad libitum intake and 75%, 50%, 25% and 0% (fasting) of ad libitum). Zero-activity HP increased with decreasing Ta and increasing food intake. However, at 14 degrees C, zero-activity HP in birds fed ad libitum and 75% did not show further increase, but those in birds fed less than 75% of ad libitum increased rapidly. Results of the regression of zero-activity HP on Ta ranging from 32 degrees to 17 degrees C indicated that the slope was affected little by food intake, but the intercept decreased with decreasing food intake. Tb increased significantly with increasing food intake. There was little variation with Ta but, at and above 27 degrees C, a slightly increased Tb was observed only in birds fed ad libitum. Overall effects of Ta and food intake on HIF (% TME intake) were not found, but HIF tended to increase with decreasing food intake at 14 degrees C. Total energy retention and energy retention as fat decreased with decreasing Ta and food intake, although energy retention as protein decreased only with decreasing food intake. Results obtained here suggest that availability of TME is affected little by Ta ranging from 32 degrees to 17 degrees C and that HIF is utilised, in part, to maintain Tb at any Ta.

Circadian variation in heat production and respiratory quotient in growing broilers maintained at different food intakes and ambient temperatures.

1. Circadian variations in heat production (HP) rate and respiratory quotient (RQ) were measured in growing broilers maintained at 5 ambient temperatures (14 degrees, 17 degrees, 22 degrees, 27 degrees and 32 degrees C) and at 5 rates of feeding [ad libitum intake and 75%, 50%, 25% and 0% (fasting) of ad libitum intake]. 2. In most cases, the HP rate decreased from 10.30 h just after food was given) until 00.30 h (the 1-h dark period), showed an overshoot just after the 1-h dark period and then changed little. 3. Circadian variation in RQ, except in the fasted group, showed a similar pattern, which consisted of increase, decrease and constant phases. 4. Food intake affected the pattern of circadian variation in RQ, although ambient temperature had little effect. Possible effects of food intake on the pattern of circadian variation in HP rate were discussed.

Incidence of pecking damage in growing bantams in relation to food form, group size, stocking density, dietary tryptophan concentration and dietary protein source.

1. This paper reports 4 experiments with groups of 10 to 20 growing bantams in multi-unit brooders, which investigated effects of certain environmental and dietary factors on development of feather pecking damage to 6 weeks of age. Damage was assessed according to a subjective scoring system. 2. A test of food form (pellets, mash, mash diluted with 100 g/kg powdered cellulose) confirmed that pecking damage tends to be greater with pellets than with mash but there was no significant difference between the low damage scores associated with undiluted and diluted mash treatments. 3. A test of group size (10, 20 birds) and stocking density (744, 372, 186 cm2/bird) showed that variation in pecking damage was associated with group size x density interactions. 4. A test of dietary supplementation with L-tryptophan (0, 10, 20 g/kg) showed suppression of pecking damage with the higher (20 g/kg) dose, compared with the control (0 g/kg) treatment. 5. A test of dietary protein source (plant, mainly animal, mainly semipurified) showed no difference in pecking damage scores between treatments.

Effects of amino acid balance and energy:protein ratio on energy and nitrogen metabolism in male broiler chickens.

1. An experiment was performed with growing broiler chickens (14 to 21 d old) to examine 3 diet characteristics which have been implicated in regulatory elevation of metabolic rate: an imbalanced amino acid mixture, high dietary energy concentration and low protein concentration. 2. Differences in energy expenditure could be explained almost entirely (93%) by differences in quantities, and therefore costs, of protein and fat accretion. There was no indication of regulatory diet-induced thermogenesis. Heat production was not significantly correlated with CP:TME ratio and was negatively correlated (P < 0.01) with dietary TME concentration. 3. Heat production was closely correlated (P < 0.001) with rate of protein accretion, which in turn was more strongly associated with intake of the first-limiting amino acid (lysine) than with total protein intake. Heat production on an imbalanced, lysine-limited, amino acid mixture was no greater than on a balanced amino acid source with the same lysine concentration. 4. There was no indication of a stimulation of heat production by excess amino acids. Heat production, adjusted for body weight by covariance analysis, was similar on paired diets which had identical lysine concentrations but a 1.5- or 2-fold difference in crude protein concentration. 5. There was a strong negative correlation (P < 0.001) between protein retention per g of lysine consumed and lysine: CP ratio, suggesting that, in this case, response to a limiting amino acid was improved by the presence of a super-abundance of other amino acids.

Diet selection by Japanese quail (Coturnix coturnix japonica) in relation to ambient temperature and metabolic rate.

1. A choice between a high-energy, wheat-based, low protein mixture and a lower-energy, soya-based, high protein mixture offered to growing Japanese quail at ambient temperatures of 20 degrees, 25 degrees, 30 degrees and 35 degrees C. 2. the quail were kept in open-circuit respiration calorimeters, so that diet selection could be related to energy requirement. 3. Increasing ambient temperature had no significant effect on food intake by weight, but the proportion of the high energy choice decreased and, conversely, the proportion of the lower-energy but higher-protein choice increased. 4. Energy intake was therefore negatively correlated with ambient temperature, but protein intake per unit of energy intake increased, allowing the birds to gain weight at about the same rate at all temperatures. 5. Heat production decreased as ambient temperature increased. Respiratory quotient decreased with increasing temperature, which indicates a reduced utilisation of carbohydrate as an energy source. 6. Water intake increased with temperature but there were no overt signs of heat stress and there was no significant change in body temperature. 7. Japanese quail selected a dietary mixture which maintained similar growth rates over a wide range of ambient temperature, by sustaining protein intake but altering energy intake in line with thermoregulatory energy demands.

Effect of cycling temperature on growth, energy metabolism and nutrient retention of individual male turkeys.

1. Each week, from 12 to 20 weeks of age, male turkeys of a heavy strain were subjected to cool (C; 16 degrees C), hot (H; 29 degrees C), and cycling temperatures, and fed on a standard diet ad libitum for 4 d. Lighting was intermittent, 3 h on, 3 h off. Food was given when lights were on. Those given cycling temperatures (3 h C; 3 h H) were given food and light during the cool (eat-when-cool, EC) or hot (EH) periods. 2. Birds in all treatments gained similar amounts of weight from 12-14 weeks of age. Thereafter, birds in C maintained gains, the body weight gains of birds in EC and EH declined moderately and birds in H lost weight. 3. Birds in C produced more metabolic heat. Those in H showed increased heat production as they became older. 4. Protein retention was greater in turkeys in C, EC and EH. It was lower in H, becoming negative between 18-20 weeks of age. Birds in H suffered body fat losses which increased with age. 5. Birds in EH and EC gained similar amounts of body weight. Birds in EH exhibited lower heat production and greater energy retention than those in EC. 6. Body temperatures were higher in H than in the other environments.