Only 7% of the variation in feed efficiency in veal calves can be predicted from variation in feeding motivation, digestion, metabolism, immunology, and behavioral traits in early life

Abstract

High interindividual variation in growth performance is commonly observed in veal calf production and appears to depend on milk replacer (MR) composition. Our first objective was to examine whether variation in growth performance in healthy veal calves can be predicted from early life characterization of these calves. Our second objective was to determine whether these predictions differ between calves that are fed a high- or low-lactose MR in later life. A total of 180 male Holstein-Friesian calves arrived at the facilities at 17 ± 3.4 d of age, and blood samples were collected before the first feeding. Subsequently, calves were characterized in the following 9 wk (period 1) using targeted challenges related to traits within each of 5 categories: feeding motivation, digestion, postabsorptive metabolism, behavior and stress, and immunology. In period 2 (wk 10-26), 130 calves were equally divided over 2 MR treatments: a control MR that contained lactose as the only carbohydrate source and a low-lactose MR in which 51% of the lactose was isocalorically replaced by glucose, fructose, and glycerol (2:1:2 ratio). Relations between early life characteristics and growth performance in later life were assessed in 117 clinically healthy calves. Average daily gain (ADG) in period 2 tended to be greater for control calves (1,292 ± 111 g/d) than for calves receiving the low-lactose MR (1,267 ± 103 g/d). Observations in period 1 were clustered per category using principal component analysis, and the resulting principal components were used to predict performance in period 2 using multiple regression procedures. Variation in observations in period 1 predicted 17% of variation in ADG in period 2. However, this was mainly related to variation in solid feed refusals. When ADG was adjusted to equal solid feed intake, only 7% of the variation in standardized ADG in period 2, in fact reflecting feed efficiency, could be explained by early life measurements. This indicates that >90% of the variation in feed efficiency in later life could not be explained by early life characterization of the calves. It is speculated that variation in health status explains a substantial portion of variation in feed efficiency in later life. Significant relations between fasting plasma glucose concentrations, fecal pH, drinking speed, and plasma natural antibodies in early life (i.e., not exposed to the lactose replacer) and feed efficiency in later life depended on MR composition. These measurements are therefore potential tools for screening calves in early life on their ability to cope with MR varying in lactose content.

Phenotypically divergent classification of preweaned heifer calves for feed efficiency indexes and their correlations with heat production and thermography

“…In addition, ADG was not different between groups during the entire period (Table 2). It has been reported that RFI is repeatable within animal at different rearing phases, as the selection of animals based on RFI during the growth phase was predictive of the RFI rank of lactating cows and of veal calves (Gilbert at al., 2017). Furthermore, differences in gene expression associated with protein turnover and associated heat production in metabolically active tissues such as the liver and the gastrointestinal tract have been hypothesized as an alternative for increased understanding of the molecular mechanisms leading to variations in energy expenditure in cattle of similar BW and ADG (Nkrumah et al, 2006).…”

“…Holstein heifer calves selected according to varying RFI during the growth phase presented divergences in RFI during the first lactation, even though the divergences were reduced at that time Gilbert et al, 2017). It has been observed that this variation in RFI has moderate heritability (h 2 = 0.45, Crowley et al, 2010).…”

Individual characteristics in early life relate to variability in weaning age, feeding behavior, and weight gain of dairy calves automatically weaned based on solid feed intake

“…However, their models did not include behavioral factors known to contribute to preweaning calf performance. For instance, Gilbert et al (2017) showed that drinking speed and fearfulness (response to human contact and Individual characteristics in early life relate to variability in weaning age, feeding behavior, and weight gain of dairy calves automatically weaned based on solid feed intake movement on a weigh scale) were negatively associated with weight gain in veal calves, and Neave et al (2018a) found that personality traits in dairy heifers (such as interactive, exploratory, and vocal responses when exposed to novel situations) were related to feeding behavior and performance before and during weaning. Behavioral measures in these studies were taken when calves were several weeks to several months of age; it is possible that other behaviors recorded at an early age may explain variability in feeding behavior, growth, and suitability to wean early.…”

The role of colostrum for the newborn thermogenesis and feeding strategies for calves raised in low temperatures

“…Mean concentrations of NEFA tented to be greater in NC versus HRAS (P = 0.06) from birth to week 7 ( Figure 6), probably due to lower glucose levels. Concentrations of NEFA are sensitive to plasma glucose, and indicates greater mobilization of fat due to low nutrient intake (Abdelgadir et al, 1996;Zhang et al, 2010;Gilbert et al, 2017). Preweaning contrasts: NC versus HRTS (P = 0.12), NC versus HRAS (P = 0.05), MR versus WM (P = 0.14), TS versus AS (P = 0.62).…”