Fetal developmental programming is a well established concept. Maternal nutrition has been observed to influence offspring development in livestock and other animal species. This experiment evaluated the effects of dietary restriction in yearling heifers during the peri-conception period and first trimester upon progeny growth, physiology and reproduction. The feedlot performance, appetite and carcass characteristics of the offspring are presented here.
Bos Indicus cross heifers were individually fed high (14% crude protein(CP)) or low (7%CP) diet for 60 days prior to conception. At 23days post-conception, each high(HPERI) or low(LPERI) group was again split into high (HPOST) or low (LPOST) diet groups in a 2x2 factorial design. From the end of the first trimester (98dpc) heifers (n=64) were fed to meet nutritional requirements until term. The singleton entire male progeny (n=39) were fed to a standard industry endpoint before slaughter at 18-months.
Liveweight and feed conversion ratio between bulls did not differ due to maternal diet (Two-way ANOVA;P>0.10). Feed intake varied with a significant interaction (P<0.05) between maternal PERI and POST diet such that progeny of dams that had a change in diet (LH and HL) had 9% higher daily feed intake on test than those whose dams received low diet throughout the PERI- and POST-conception period (LL). A similar pattern was apparent in feedlot growth-rate and net feed intake but the differences were not significant (P>0.10). Carcass weight was similar, however dressing%, yield and eye muscle area (88.0±2.61vs81.1±1.8cm2) were higher (P<0.05) for HPost bulls who also tended to be leaner (15.7±1.2vs18.7±0.6mm;P=0.6). Combined, these results suggest that the diet perturbation in early gestation has altered the pattern of development of both the appetite regulatory system and fetal skeletal muscle leading to persistent post-natal effects.
Acknowledgements: We are indebted to S.Kidman and Co., Ridley Agriproducts and ARC for funding this research.