The objective of the present experiment was to test whether the relationship between feed composition and the efficiency of protein utilization in pigs was different between two very different breeds. Fortyeight entire male pigs, half Large White x Landrace (LW x ) and half Chinese Meishan (CM), were assigned at 13 kg live weight either to an initial slaughter group or to one of six feeding treatments for 6 weeks. The two feeds used were starch, with 1252 M J metabolizable energy (ME) and 0 kg digestible crude protein (DCP)/kg, and a high-protein feed, with 11.95 M J M E and 0.362 kg DCP/kg. In the first week the LW x pigs were given 400 g high-protein feed/d with 0, 100, 200 or 300 g starch/d, or 200 g high-protein feed/d with 400 or 500 g starch/d. The six diets had ME:DCP ratios of between 33 and 119 MJ/kg. The diet compositions were held constant within each of the six treatments but the allowances were increased weekly on time-based linear scales to be 2.25 as great in week six as in week one. The allowances for the C M pigs were 0.75 of those for the LW x . The calculated efficiency of protein utilization, ep, was found to be directly proportional, up to a maximum value, to the ME:DCP ratio of the diet for both breeds, as found previously for LW x male and female pigs. The overall constant of proportionality was ep = 0.0108 (SE 0.00024) ME:DCP, the value of which did not differ significantly between the two breeds. The maximum observed ep values were 0.710 (SE 0.014) and 0.824 (SE 0.016) for the LW x and C M pigs respectively. It is likely that the lower maximum value for the LW x pigs was an experimental artefact due to increased feed spillage by these pigs on the two highest starch allowances used. In previous experiments the maximum value of ep was found to be 0,813 for LW x pigs, a value similar to that found here for the C M pigs. The results are consistent with the view that the two very different pig breeds have the same net efficiency in using protein and use the same rules for partitioning a scarce resource such as energy.Breeds: Efficiency of protein utilization: Energy intake: Meishan: Pigs It has been observed (e.g. Campbell et al. 1985a, b) that the rate at which pigs retain protein can be increased, at a given rate of protein supply, by increasing the rate of supply of energy. One explanation of such findings is the that the pig 'values' some rate of positive lipid retention more highly than the achievement of an increased rate of protein retention and, therefore, some of the protein supply is used for lipid gain. Such a 'partitioning rule' explanation was particularly advocated by Whittemore (1983) who proposed that there was some minimuin value for the 1ipid:protein ratio in the gain that the pig would not be prepared to go below. Such an explanation raises several difficulties, but it does open the possibility that different kinds (genotypes) of pigs could differ in the minimum value of the 1ipid:protein ratio in their gain that they would be prepared to accept. In order to predict the gr...

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The goal of this study was to determine the e#ect of feeding rosemary and a-tocopheryl acetate on hen performance and egg quality. Ninety-six Lohmann laying hens, -,-week-old, were allocated into four groups.

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1. Grouped laying hens were fed on experimental diets containing dried tomato pulp (DTP) at inclusion rates up to 120 g/kg and two control diets (A and A+Carophyll). 2. The addition of DTP did not significantly affect egg production, food consumption and efficiency, egg weight and shell thickness. 3. There was a significant improvement in the egg yolk colour in treatments containing DTP. However, this improvement was significantly lower in comparison to the diet which contained carophyll.