Recent research has demonstrated that plane of nutrition during gestation of the mother cow can influence the performance and health of the calf and potentially her performance as a lactating cow.
This is stated by dairy consultant Bill Woodley in his expert opinion on DairyGlobal.net. He explains several examples. For instance, data from beef and sheep studies that examined nutrient restriction during the 1st trimester show a reduction in plasma concentrations of major regulators of glucose homeostasis such as cortisol, thyroid hormones, and insulin (Symonds et al., 2010). This mechanism, known as the glucose sparing effect of pregnancy, allowed the animal to maintain glucose levels for the foetus to maintain consistent foetal growth. However, the endocrine sensitivities of a large number of foetal organs are essentially reset. (Effect of Maternal Nutrition on Calf Health and Growth, Jon Schoonmaker). A study by Long et al. (2012) reported that a 30% nutrient restriction during early gestation in cattle did not affect birth, weaning, or yearling slaughter weights, however fat cell size was increased and muscle size was decreased at slaughter after 1 year of age.
The data concluded that “heifers from heifers” produced more milk and had improved longevity as compared to “heifers from mature animals”. Photo: Henk Riswick
Effect of heat stress on calves
But also heat stress can have an effect. A number of studies demonstrate that calves born to cows exposed to heat stress during the dry period (3rd trimester) have lower birth weight (Collier et al., 1982; Tao et al., 2012), weaning weight, and compromised passive immune transfer. Further studies have examined the long-term effects on the calf. A recent analysis of historical data by Monteiro, Tao, Thompson, and Dahl (University of Florida) demonstrated that in utero heat stress decreased calf survival and performance through the first lactation. Animal data was obtained from 5 previous experiments conducted during 5 consecutive summers and were pooled and analysed. The experiments took place at the Dairy Unit of the University of Florida (Hague) during the period of 2007 to 2011. The data demonstrated that the in utero heat stressed heifers produced 5.1 kg/day less milk to 35 weeks of the 1st lactation compared with cooled heifers. The researchers concluded that this is likely explained by differences in mammary gland development and altered metabolic efficiency because of changes in the metabolism of those calves that experienced heat stress in utero. The last example is based on historical data from a large Spanish data-set (Gonzalez-Recio et al. 2012) that examined the effect of dam parity on milk yield of the offspring. The data concluded that “heifers from heifers” produced more milk and had improved longevity as compared to “heifers from mature animals”. There are currently no data to explain these differences but it is thought that foetal programming may play a role. In most situations, the growing heifer is under less nutritional and physiological stress than the lactating animal.
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