1. Respiration calorimetry measurements were made over 4 d on normally-fed groups of 10 male or 10 female quail during three periods commencing at 12, 19 and 26 d of age. Carcass compositions were determined on groups of birds of each sex at 2 and 5 weeks of age. 2. Expressed per unit body weight, food and metabolisable energy (ME) intake and weight gain decreased between 2 and 3 weeks of age, but remained constant thereafter. 3. No differences were observed between sexes for any variable measured. Efficiency of utilisation of ME for energy retention was only 0.33. This was mainly because the majority of energy was retained as protein tissue. 4. Nitrogen (N) retention (g/d) increased with increasing dietary N intake but when expressed as a proportion of N intake, declined from 0.46 at 2 weeks to 0.33 at 4 weeks. Fat retention increased substantially during week 4. 5. Carcass analyses showed that fat, protein and ash were higher for quail at 5 weeks than at 2 weeks of age. At 5 weeks carcass fat was only 60 g/ kg.
In three experiments laying performance was studied in hens given graded levels of maldison, dichlorvos and pirimiphos-methyl either separately or combined in the feed over a four-week test period. Results conclusively demonstrated interaction between dichlorvos and maldison as measured by depressed food consumption and egg production. Combining the three insecticides at levels which when given separately had no effect, severely depressed food consumption and egg production. After four weeks on treatment, birds receiving pirimiphos-methyl at 50 �g/g of diet had residues of 0.08-0.17 �g/g in fat and 0-0.06 �g/g in muscle, and residues of 0-0.07 �g/g maldison were recovered in the fat of birds receiving it at 100 �g/g of diet. No residues of any insecticide were detected in eggs and no dichlorvos residues were detected in any tissues. Plasma acetylcholinesterase (AChE) levels were reduced by 70% with dichlorvos at 30 �g/g, by 30% with maldison at 100 �g/g and by 90% with pirimiphos-methyl at 50 �g/g. There was no indication of potentiation between insecticides as measured by plasma AChE inhibition, and effects upon food consumption and egg production appeared unrelated to plasma AChE activity. The relationship between food consumption and egg production was similar in groups receiving dichlorvos-maldison mixtures and in those receiving graded levels of untreated food, indicating that the insecticides' effect upon egg production was mediated via a reduced food intake. Maximum residue limits for pesticides in feeds should be based on a total index which takes account of interaction between the different pesticides present.
Two factorial experiments were used to determine the effect of frequency of insemination and of dose and dilution rates on fertility in two and three breeds of chickens respectively. The semen used in both trials was obtained from a group of Synthetic breed cockerels. (The Synthetic breed was a closed population based on White Leghorn-Australorp crosses). In the frequency of insemination trial, White Leghorn and Australorp pullets were used. White Leghorns were more fertile than Australorps at both weekly and twice weekly inseminations (P<0.001). Australorp pullets had significantly higher fertility when inseminated twice a week compared to once a week (P<0.001). White Leghorn fertility improved to a far lesser extent with the more frequent inseminations. In the dose dilution trial, Australorp, Leghorn, and Synthetic pullets were used. With inseminations at once a week, over the three breeds, ninety per cent fertility was obtained when dose-dilution combinations provided between 0.03 and 0.04 ml of undiluted semen. Leghorns and Synthetics appeared to be more fertile than Australorps although the differences were not significant.
Calorimetric measurements were made on groups of Japanese quail selected for increased body weight at either 20 or 35 days on either a high- or low-nutrient density diet. For the majority of biological parameters measured, the selected lines outperformed the unselected controls. Weight gain, metabolizable energy (ME) intake, food conversion efficiency, and energy retention were greater for the selected than for the control line. The major difference between the two groups was the higher mean food consumption of the selected lines. Quail selected at 35 days on the high nutrient density diet ate more food, gained more weight and retained more energy and body fat than those selected at the same age on the low nutrient density diet. Net availability of ME for growth was the same (0.69) for the selected and unselected lines; it was 0.66 for protein deposition and 0.83 for fat deposition. Maintenance energy requirement for eight quail was 1.2 MJ ME (kg wt)-1 day-1. Retention of dietary nitrogen was 0.61 of nitrogen intake. There was no difference between the lines in starvation heat production. However, birds fed ad libitum prior to starvation had a 12% higher heat production than those restricted to 70% of ad libitum feed.
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