Effect of different alfalfa hay levels on growth performance, rumen fermentation, and structural growth of Holstein dairy calves1

Abstract

Introducing forage in dairy calf diets during the preweaning period stimulates development of rumen capacity and function and gut wall integrity. It was hypothesized that calves fed alfalfa hay (AH) at greater levels (up to 25% of DM) would result in an increase in starter diet intake and growth performance. The objective of this study was to determine the effects of increasing levels of supplemental AH on growth performance, rumen fermentation, blood metabolites, and feeding behavior in intact male dairy calves. For this purpose, 45 Holstein male calves (3 d of age and 41 ± 2.5 kg of BW) were randomly assigned to 1 of the following 3 starter diets differing in their forage level: 1) diet without AH (control), 2) diet with 12.5% AH on a DM basis, and 3) diet with 25% AH on a DM basis. Supplementation of AH in the starter diets linearly increased total DMI and ADG during the postweaning ( < 0.01) and overall ( = 0.02) periods. Alfalfa hay supplementation linearly increased ( < 0.01) ruminal pH on d 35 and 70 of the study. The concentrations of total VFA ( = 0.85), acetate ( = 0.74), propionate ( = 0.93), and butyrate ( = 0.91) were not affected by treatments. Furthermore, forage supplementation tended (linearly, = 0.08) to increase the acetate to propionate ratio compared with the control calves. Blood β-hydroxybutyrate (BHBA) concentrations in the control calves were less ( = 0.03) than in the AH-fed calves on d 70 of the study. Among all the measured variables of skeletal growth, supplementation of AH in the starter diets linearly increased heart girth ( = 0.05) and abdominal girth ( < 0.01) on d 70 of the study. These results indicate that the feed intake, feeding behavior, rumen fermentation parameters, and blood BHBA concentration may be affected by rations differing in AH level so that providing calves with 25% AH can improve calf performance.

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

“…Most of the studies (21 studies, accounting for 84% of summarized studies) explored in this review showed a positive effect of forage inclusion on rumen fluid pH in dairy calves, while very few reported no difference (four studies, accounting for 16% of summarized studies) or negative impact (Table 7). In agreement with a previous meta-analysis, our literature search showed that forage could improve the rumen fluid pH when supplemented to calves, though it might be dependent on the forage source [38,40]. Alfalfa hay is more likely to modulate rumen fluid pH during the milk-feeding period than other types of forages [33].…”

“…In the early 2000s, several studies began to investigate the effect of lower levels of forage inclusion in the diet on pre-weaned calf performance. Most of them included a proportion of forage ranging between 5 and 25% of total solid feed intake [15,19,22,27,[37][38][39][40]. In contrast to previous studies, most studies either reported an increase [19,22,38,40] or a lack of differences [27,37] in DMI, ADG, and BW, indicative of multifactorial effects in these studies.…”

“…Feeding alfalfa hay at 10% of total solid feed increased the overall DMI, ADG, and final BW, and thereby shortened the time to weaning at a target DMI of starter (1 kg for 3 consecutive days), compared with feeding 0 or 5% of alfalfa hay [22]. Nemati et al [38] also observed a linear increase in total DMI and ADG during the postweaning (d 52 to 70) and overall periods (d 3 to 70) of calves supplemented with chopped alfalfa hay at 0, 12.5, and 25% on dry matter (DM) basis. However, gut fill could be a confounding factor when evaluating the effect of forage feeding on improving ADG in dairy calves.…”

“…On the one hand, forage is bulkier and has lower digestibility compared to the concentrate. The higher forage consumption leads to increased intake of effective fiber, which in turn stimulates the chewing (ruminating and eating) activity of calves [56,95], and subsequently improves the saliva production and rumen buffering [38,63]. On the other hand, the rapidly fermentable carbohydrates generate abundant VFA that may exceed and overwhelm the absorptive capacity of the undeveloped rumen [96].…”

Effects of replacing Leymus chinensis with whole-crop wheat hay on Holstein bull apparent digestibility, plasma parameters, rumen fermentation, and microbiota

“…The total VFA concentrations were unaffected among the groups, which might be the result of the same ratio of forage to concentration of treatment diets 36 , or might be caused by the fact that the output of total VFA was equivalent to the amount of absorption in the rumen among all treatments 37 . In the present research, the observed concentrations of acetate and propionate, and the acetate to propionate ratio were not significantly different, probably because of the similar ruminal pH values caused by the dietary-associated shifts 38 .…”