Effect of digestible fiber content of barley silage on lactation performance and chewing activity of lactating dairy cows in comparison with corn silage

Abstract Text: There is a limited knowledge on evaluating barley silage with different digestible fiber content on dairy cow performance. The objective of this study was to evaluate the effects of barely silage varieties selected for varying rates of in vitro NDF digestibility on DM intake (DMI), milk production, and total chewing activity of high-yield dairy cows in comparison with corn silage. Four early lactating multiparous Holstein cows (average body weight = 703 ± 78 kg; days in milking = 101 ± 25; parities= 2.75 ± 0.83) were used in a 4 × 4 Latin square design. The cows were fed diets that contained 49% barley-based concentrate and 51% forage (DM basis). The forage consisted of 10% alfalfa hay and 41% silage. The four whole plant silages were: corn silage (P7213R), CDC Cowboy barley silage, CDC Copeland barley silage, and Xena barley silage. The diets were formulated to meet the nutrient requirements by lactating dairy cows producing 40 kg of milk using NDS software. The in vitro 30 h NDF digestibility (NDFD) of CDC Cowboy, CDC Copeland and Xena varieties were 37, 31 and 29%, respectively. The experiment consisted of 18 days of adaptation and 5 days of data collection. Statistical analyses were performed using PROC MIXED procedure of SAS 9.4 with significance declared at P<0.05.  The results indicate that barley silage variety did not influence DMI, milk production and chewing activity (P> 0.1). The CDC Cowboy with higher NDFD did not result in an improvement in milk yield (averaged 35.3 ± 1.71 kg /d, P> 0.1), feed efficiency (averaged 1.37 ± 0.07 DMI/milk yield, P> 0.1), and total chewing activity (averaged 892 ± 23 min/d, P> 0.1) compared with other barley silage varieties. Cows fed the corn silage had similar DMI (averaged 26.3 ± 1.4 kg/d, P> 0.1) but produced more milk than those fed barley silage (40.1 vs. 35.3 ± 1.71 kg /d, P< 0.05). As a result, the cows fed corn silage had improved feed efficiency compared with those fed barley silage (1.57 vs. 1.37 ± 0.07 DMI/milk yield, P< 0.05). The results of this study indicate that feeding barley silage with higher digestible fiber content does not necessarily result in greater milk production performance. However, feeding corn silage has potential to produce more milk and better feed efficiency compared with barley silage.

Keywords: fiber digestibility, chewing activity, milk yield