SUMMARYLactation is the most energy-demanding phase of mammalian reproduction, and lactation performance may be affected by events during pregnancy. For example, food intake may be limited in late pregnancy by competition for space in the abdomen between the alimentary tract and fetuses. Hence, females may need to compensate their energy budgets during pregnancy by reducing activity and lowering body temperature. We explored the relationships between energy intake, body mass, body temperature and physical activity throughout pregnancy in the MF1 mouse. Food intake and body mass of 26 females were recorded daily throughout pregnancy. Body temperature and physical activity were monitored every minute for 23h a day by implanted transmitters. Body temperature and physical activity declined as pregnancy advanced, while energy intake and body mass increased. Compared with a pre-mating baseline period, mice increased energy intake by 56% in late pregnancy. Although body temperature declined as pregnancy progressed, this served mostly to reverse an increase between baseline and early pregnancy. Reduced physical activity may compensate the energy budget of pregnant mice but body temperature changes do not. Over the last 3days of pregnancy, food intake declined. Individual variation in energy intake in the last phase of pregnancy was positively related to litter size at birth. As there was no association between the increase in body mass and the decline in intake, we suggest the decline was not caused by competition for abdominal space. These data suggest overall reproductive performance is probably not constrained by events during pregnancy. Supplementary material available online at
The objective of this study was to investigate the potential causes of high body temperature (Tb) during lactation in mice as a putative limit on energy intake. In particular we explored whether or not offspring contributed to heat retention in mothers while suckling. Tb and physical activity were monitored in 26 female MF1 mice using intraperitoneally implanted transmitters. In addition, maternal behaviour was scored each minute for 8 h d−1 throughout lactation. Mothers that raised larger litters tended to have higher Tb while nursing inside nests (P < 0.05), suggesting that nursing offspring may have influenced heat retention. However, Tb during nursing was not higher than that recorded during other behaviours. In addition, the highest Tb during the observation period was not measured during nursing behaviour. Finally, there was no indication that mothers discontinued suckling because of a progressive rise in their Tb while suckling. Tb throughout lactation was correlated with daily increases in energy intake. Chronic hyperthermia during lactation was not caused by increased heat retention due to surrounding offspring. Other factors, like metabolic heat produced as a by-product of milk production or energy intake may be more important factors. Heat dissipation limits are probably not a phenomenon restricted to lactation.
Corn-Cob Meal (CCM) is a waste product derived from maize grain shelling corn cob which constitutes nuisance to the environment and it can be included in poultry diet in order to reduce competition between man and animal. Hence, a 63-day feeding trial was conducted in a completely randomized design to determine performance characteristics and blood profile of broiler chickens fed corn-cobs based diets with or without enzyme supplementation. One hundred and sixty five (165) birds were randomly allotted into five dietary treatment groups; T1: (0% CCM), T2 (10% CCM without enzyme), T3 (20% CCM without enzyme), T4 (10% CCM with enzyme), T5 (20% CCM with enzyme) with each treatment comprising three replicates of eleven birds per replicate. Parameters measured include performance characteristics, haematological and serum biochemical indices. The result revealed that there were no significant difference (P>0.05) on performance characteristics of broiler chicken observed except for Average Daily Feed Intake (ADFI) and the Feed Conversion Ratio (FCR). Birds fed 10% and 20% CCM based diet without enzyme recorded the highest value of ADFI (129.38 g/b/d and 130.85 g/b/d) while birds fed 20% CCM based diet with enzyme supplementation had the best FCR value (2.18). The haematological parameters were not significantly influenced (P>0.05) by the diets except for lymphocytes and heterophil count with the highest lymphocytes value in T2 (68.00%) and the lowest value in T5(53.67 %). Birds on T5 had significantly (P<0.05) highest heterophil value (40.67%). The serum biochemical indices were not significantly influenced (P>0.05) by the diets except for aspartate aminotransferase. However, values obtained in this study fell within the normal range recommended for healthy broiler chicken. Based on this result, it can be concluded that CCM with enzyme supplementation can be incorporated into broiler diet up to 20% without any detrimental effect on their performance and blood profile.
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