Fetal programming is a term used to describe the effect that the mother's environment can have on the fetus during pregnancy. When discussing this area of research, it is rarely concerning positive effects, as much of the concern is limiting the negative impacts on the pregnancy. One of these impacts is nutrition, or more accurately, the lack thereof.
The cows' nutritional requirements change depending on the animal's status, with different requirements open, pregnant, and lactating cows. The fetus may not have a high nutrient requirement during the first trimester of pregnancy compared to the latter two, but the lack of nutrition availability can impact foundational pregnancy development.
Researchers in Spain studied undernutrition's effect on fetuses, specifically the growth rate and meat quality characteristics of a calf born to an underfed cow during the first trimester. Cows were represented by Parda de Montaña and Pirenaica cattle breeds.
Cows were randomly assigned to one of the two treatments, the control group was fed 100% of their nutrient requirements, and the undernutrition group was fed 65%. These treatments continued for the first 81 days of pregnancy, followed by all animals receiving 100% of their requirements.
After birth, using only bulls from this point forward, the calves consumed their mother's milk exclusively and then were weaned at four months of age. The calves were entered into a feedlot and fed a typical high-concentrate feedlot ration until they were heavy enough for slaughter.
To say there was an impact of undernutrition is an understatement. Calves born to undernutrition cows had significantly lower weaning weights and slaughter weights. Specifically, the undernutrition Pirenaica bulls were 16% and 14% lighter than their control counterparts at weaning and slaughter, respectively.
Testicular development was significantly lower in the undernutrition calves as well as average daily gain. This is likely because the testicular growth rate is highly correlated to sexual maturity and, subsequently, sexual maturity with growth. Undernutrition appears to have impacted the height of the calves, where both undernutrition groups were shorter in stature than the control.
The Pirenaica calves from underfed cows had the greatest concentration of circulating free fatty acids (non-esterified fatty acids; NEFA). Additionally, the undernutrition animals had the greatest subcutaneous body fat. These elevated NEFA and high adipose levels demonstrate that the metabolic functions of the undernutrition calves have been altered and that more energy is being put towards adipose stores and less towards muscle.
Interestingly, each treatment group had similar intramuscular fat, even though the undernutrition Pirenaica calves had far more fat cover. Finally, all control calves had more tender meat than the undernutrition calves – however, all groups had moderate to low levels of tenderness in this study.
This study has demonstrated the impact of undernutrition on the fetus during the first trimester of pregnancy. These researchers bring to light the importance of ensuring cows have an adequate plane of nutrition during gestation and the costs it can bring to the operation if not.
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