Effects of Feeding Milk Replacer Ad Libitum or in Restricted Amounts for the First Five Weeks of Life on the Growth, Metabolic Adaptation, and Immune Status of Newborn Calves

Abstract

The pre-weaning period is critical for calf health and growth, and intensive milk feeding programs may assist postnatal development by improving body growth and organ maturation. The aim of the present work was to study the effects of ad libitum milk replacer (MR) feeding on the growth, metabolic adaptation, health, and immune status of newborn calves. Twenty-eight newborn Holstein and Holstein x Charolais crossbred calves were fed ad libitum (ADLIB) or in restricted amounts (6 liters per day; RES) during the first five weeks of life. The MR intake in the ADLIB treatment was gradually reduced at weeks 6 and 7, and all calves then received 6 liters of MR per day until day 60. Blood samples were collected to measure the plasma concentrations of metabolites, insulin, insulin-like growth factor (IGF)-I and IGF binding proteins (IGFBP), immunoglobulins, and acute phase proteins. The expression of mRNA associated with both the somatotropic axis and gluconeogenic enzymes was measured in the liver on day 60. Intensive feeding improved MR intake and growth in ADLIB without influencing concentrate intake. Carcass weight, perirenal fat, and muscle mass were greater in ADLIB. Plasma concentrations of glucose, triglycerides, insulin, and IGF-I were greater, whereas plasma concentrations of β-hydroxybutyrate, total protein, albumin, urea, IGFBP-2 and -4, and fibrinogen were lower at distinct time points in ADLIB. The hepatic mRNA expression of cytosolic phosphoenolpyruvate carboxykinase was greater in ADLIB. Most metabolic and endocrine differences occurred during the MR feeding period, but a slightly greater concentrate intake was associated with increased plasma IGF-I and insulin at the end of the study. The immune and health status of the calves were not affected by MR feeding. However, increased plasma fibrinogen in the RES group suggested differences in the acute phase response.

Role of early life nutrition on the hypothalamic-pituitary-testicular axis of the bull

“…Similar results for globulin and total protein concentrations have been observed where calves were offered restricted compared with an unlimited milk allowance (Hammon et al 2002). Several studies including a recent report by Schäff et al (2016) have shown that systemic concentrations of albumin increase steadily in the weeks after birth. In our study, we observed a steady increase in concentrations of albumin over time in HIGH calves, with greater concentrations compared to their contemporaries on LOW during the post-weaning period.…”

Short communication: The effects of offering a high or low plane of milk preweaning on insulin-like growth factor and insulin-like growth factor binding proteins in dairy heifer calves

“…In the current study, feeding a high level of milk resulted in higher levels of IGF-1 detected at wk 1 until wk 5 and a tendency for an increased concentration of IGF-1 at wk 7. It has been previously shown that elevated feeding of nutrients from milk replacer preweaning increases IGF-1 (Bartlett et al, 2006;Daniels et al, 2008;Schaff et al, 2016); however, a noteworthy difference in our findings is a detectable difference in IGF-1 at wk 1 of life. Schaff et al (2016) fed an elevated level of milk replacer for the first 5 wk of life, and despite differences in actual milk intake and ME intake among their calves fed a high versus a low plane of nutrition from wk 1, a difference in IGF-1 was not observed until 29 d.…”

“…In addition, with no maximum per visit, the calf has more flexibility as to when it receives milk. Similarly, Schaff et al (2016) indicated that calves were allowed to consume 2 L per visit with no explanation of what the minimum amount was. Because of this, it is plausible that calves were visiting the calf feeder when they had accumulated from 0.5 to 2.0 L, which is less restrictive on when calves consume and how much they get per day.…”

Invited Review: Nutritional regulation of gut function in dairy calves: From colostrum to weaning

“…The results demonstrated that intake of solid feed and weight gain increased during weaning in calves fed elevated amounts of milk and weaned through the step-down method compared with those fed milk conventionally. More recent studies (Schäff et al, 2016(Schäff et al, , 2018 have also used the "step-down" method by feeding MR (125 g of MR powder per L) ad libitum for 5 wk, followed by reduction in MR proportionally day by day to 6 L of MR at wk 7 compared with calves fed only 6 L until weaning to investigate growth, metabolic adaptation, health, and rumen and small intestinal growth. The benefits reported in this study were greater perirenal fat and muscle mass and increased anabolic metabolism (as indicated by increased insulin-like growth factor 1 concentration in blood) for step-down calves compared with those who had restricted amounts of milk.…”