Effects of forage provision to dairy calves on growth performance and rumen fermentation: A meta-analysis and meta-regression

Abstract

A meta-analysis of the potential effect of forage provision on growth performance and rumen fermentation of dairy calves was conducted using published data from the literature (1998-2016). Meta-regression was used to evaluate the effects of different forage levels, forage sources, forage offering methods, physical forms of starter, and grain sources on the heterogeneity of the results. We considered 27 studies that reported the effects of forage provision to dairy calves. Estimated effect sizes of forage were calculated on starter feed intake, average daily gain (ADG), feed efficiency (FE), body weight (BW), and rumen fermentation parameters. Intake of starter feed, ADG, BW, ruminal pH, and rumen molar proportion of acetate increased when supplementing forage but FE decreased. Heterogeneity (the amount of variation among studies) was significant for intake of starter feed, ADG, FE, final BW, and rumen fermentation parameters. Improving overall starter feed intake was greater in calves offered alfalfa hay compared with those offered other types of forages. During the milk feeding and overall periods, improving ADG was greater for calves fed a high level of forage (>10% in dry matter) compared with those fed a low level of forage (≤10% in dry matter) diets. The advantages reported in weight gain at a high level of forage could be due to increased gut fill. Improving overall ADG was lower for calves offered forages with textured starter feed compared with ground starter feed. The meta-regression analysis revealed that changes associated with forage provision affect FE differently for various forage sources and forage offering methods during the milk-feeding period. Forage sources also modulated the effect of feeding forage on ruminal pH during the milk-feeding period. In conclusion, forage has the potential to affect starter feed intake and performance of dairy calves, but its effects depend on source, level, and method of forage feeding and physical form of starter feed independently of grain sources included in the starter feed.

Evaluating effects of providing hay on behavioral development and performance of group-housed dairy calves

“…Similar to previous studies conducted with individually housed calves provided lowquality hay or straw (Khan et al, 2011;Castells et al, 2012;Montoro et al, 2013), we found that providing hay to calves did not affect starter intake and therefore resulted in greater total DMI during the pre-weaning stage, particularly during the week before weaning. Interestingly, however, calves in our study selected forage at a higher inclusion rate (15%) than is often observed or recommended (e.g., <10%; Castells et al, 2012Castells et al, , 2013, and a recent meta-analysis has also suggested that high levels of forage (>10% dietary inclusion) are associated with increased starter intake (Imani et al, 2017), suggesting that further evaluation of optimal dietary inclusion of forage may be needed. Aside from effects of forage type, we speculate that the amount of hay selected may depend on milk feeding level; whereas most research in this area has been conducted with calves provided restricted milk allowances (e.g., 10% of birth weight or 4 to 5 L/d; Coverdale et al, 2004;Castells et al, 2012Castells et al, , 2013, Khan et al (2011) provided milk at the same feeding level as the present study (8 L/d) and reported similar levels of hay intake.…”

Review: How Forage Feeding Early in Life Influences the Growth Rate, Ruminal Environment, and the Establishment of Feeding Behavior in Pre-Weaned Calves

“…Forage inclusion in the pre-weaned calf diet has long been discouraged due to its negative effect on the growth rate [15,17]. However, recent research has shown that several factors need to be taken into account when evaluating the impact of forage provision on calf performance [8,9,34]. These factors include the source, amount, particle size, physical form, offering time, and feeding method of forage and concentrate, as well as the amount of milk offered and milk feeding method.…”

Characterization of the factors associated with the growth phase of dairy cattle in family farming

“…Although the forage intake during the suckling phase supports the physical development of the rumen (HILL et al, 2008), the altered fermentation profile slows down the growth of ruminal papillae (KHAN et al, 2011). In contrast, recent studies have supported the use of forage for calves during the suckling phase as a strategy to increase the concentrate intake and weight gain, and reduce abnormal calf behavior (CASTELLS et al, 2012;IMANI et al, 2017;TERRÉ et al, 2013), especially in intensive rearing systems. In addition, as the physical form of the forage may influence the development of the rumen (CASTELLS et al, 2012;MONTORO et al, 2013), the availability, digestibility, and percentage of leaves are important factors to be considered for optimizing the development of calves.…”