Abstract
The aim of this study was to evaluate the effect of the length of oat hay on the performance, health, behavior, and rumen fermentation of dairy calves. For this purpose, two hundred and ten healthy two-day-old Holstein dairy calves were randomly allocated into three groups: basic diet (calf starter) without hay (CON), or a basic diet with oat hay at either long (OL: 10–12 cm) or short (OS: 3–5 cm) length cut. The basic diet was fed from day 4, while the hay was offered from day 14. All calves were weaned at day 56 and remained in their individual hutches till the end of the trial (day 70). Calf starter intake and fecal scores were recorded daily. Bodyweight, body size, and rumen fluid samples were collected biweekly before weaning and weekly after weaning. Overall, providing oat hay (OS and OL) in the diet increased the body weight, starter intake, and average daily gain compared to the CON group. Similarly, feeding oat hay improved rumen fermentation. More specifically, hay enhanced the rumen pH and changed the rumen fermentation type. Hay fed calves spent more time on rumination but less time performing abnormal behaviors compared to control. As it can be concluded, feeding oat hay to calves enhances the growth performance, rumen fermentation, and normal calf behaviors, implying improved animal welfare irrespective of the hay length.
Highlights
Improved morphological and metabolic functions of the rumen are important at early stage of calves’ life
BW, ADG, and starter intake data are shown in Table 1 and Figures 1–3; BW was affected by the addition of hay to the diet, since higher BW was observed in calves fed hay (p < 0.01) during the whole trial period (Figure 1)
Calves fed hay had a higher BW than the CON (p < 0.01) group from the period ending on day 42 until the end of the study on day 70
Summary
Improved morphological and metabolic functions of the rumen are important at early stage of calves’ life. The normal development of the rumen epithelium depends on ingesting solid feed, and especially concentrates that produce butyric and propionic acid [1]. In the first few weeks of life, the calf cannot consume sufficient solid feed and depends mainly on milk for its maintenance, growth, and development needs. Solid feed intake increases with age, it is not until complete weaning from milk that the calf can consume adequate solid feed to support its nutritional needs, providing required substrates for growth and development of the rumen mass papillae [4]. Due to the small particle size of concentrates, plaque formation on the rumen epithelium increases, eventually leading to ruminal papillae hyperkeratosis and rumen mucosa thickening [7,8,9] and a decrease in VFA absorption [10]
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