Effect of Grains Differing in Expected Ruminal Fermentability on the Productivity of Lactating Dairy Cows

Abstract

The objective of the study was to evaluate the effect of barley and corn grains differing in expected fermentability in the rumen on dry matter intake (DMI) and productivity of lactating dairy cows. Twenty-two multiparous and 9 primiparous lactating Holstein cows (94 +/- 29 d in milk; mean +/- SD) were used in a 3 x 3 Latin square design with 21-d periods. Experimental diets contained approximately 40% of dietary dry matter as steam-rolled barley, using a lot of cultivar Dillon or cultivar Xena, or a corn mixture (CM) containing 87.5% dry ground corn, 11.4% beet pulp, and 1.1% urea (dry matter basis). Starch concentration of the grain sources was 50.0, 58.7, and 60.4% and in vitro 6-h starch digestibility was 73.5, 78.0, and 71.0%, respectively, for Dillon, Xena, and CM. All diets were formulated to contain 19.4% crude protein and 25.3% forage neutral detergent fiber. Dry matter intake (23.6 vs. 21.6 kg/d) and yields of milk (40.4 vs. 37.4 kg/d), milk protein (1.20 vs. 1.12 kg/d), and milk lactose (1.85 vs. 1.74 kg/d) were higher for cows fed CM than for cows fed barley. Although DMI was similar for cows fed Xena and Dillon (21.9 vs. 21.4 kg/d), cows fed Xena had higher yields of milk (38.5 vs. 36.2 kg/d), milk protein (1.18 vs. 1.07 kg/d), and milk lactose (1.80 vs. 1.69 kg/d) than cows fed Dillon. However, milk fat concentration tended to be higher (3.47 vs. 3.23%) for cows fed Dillon than Xena. Plasma glucose and nonesterified fatty acid concentrations were not affected by treatment, but plasma insulin concentration was higher for cows fed Xena compared with those fed Dillon (8.50 vs. 5.91 microIU/mL). Greater milk production for cows fed CM can be attributed to greater DMI. Feeding barley that was lower in starch concentration and ruminal starch fermentability (Dillon) did not increase DMI compared with feeding barley that was higher in starch concentration and ruminal starch fermentability (Xena). Reducing ruminal starch degradation of barley grain may not improve the productivity of lactating dairy cows.

The effects of and interactions between the maturity of grass silage and concentrate starch source when offered as total mixed rations on the performance of dairy cows

“…In contrast to our findings, Khalili et al (2001) reported an increase in milk protein and lactose yield in combination with increased MY when replacing dietary barley with maize. In this work, the milk composition was not altered by the starch source; this finding is consistent with the results of other researchers (DePeters and Taylor, 1985;McCarthy et al, 1989;Yang et al, 1997;Silveira et al, 2007).…”

“…Concentrate starch source The lack of effects from replacing barley-with maize-based concentrate on cows' DMI were consistent with the findings of Khalili et al (2001) but not with those of others (McCarthy et al, 1989;Overton et al, 1995;Silveira et al, 2007), who observed a reduction in the DMI of cows on barley-based diets. The diets and other experimental conditions used in the study reported herein differed from those in which feeding with barley-based concentrates resulted in DMI reduction but similar to those of Khalili et al (2001).…”

“…Barley starch is reported to be degraded rapidly and is associated with the rapid production and absorption of metabolites in the rumen of dairy cows (Nocek and Tamminga, 1991;Silveira et al, 2007), both of which can be indicative for metabolic intake regulation. The rumen fermentation rate of maize starch is slower than that of barley (Nocek and Tamminga, 1991;Mills et al, 1999;Tothi et al, 2003), which can reduce the rate of metabolite absorption.…”

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

“…Similar differences in intakes for corn and barley diets were reported by McCarthy et al (1989), Casper et al (1990) and Silveira et al (2007). Greater rate of in situ starch digestion and lower minimum daily rumen pH for BBD compared with CBD provides evidence of greater degradability of barley starch than corn starch.…”

“…Alternatively, grinding may not have had as much impact on degradability as was expected. Studies comparing corn and barley diets that recorded greater DMI for corn than barley also observed greater milk yields for corn than for barley (McCarthy et al, 1989;Silveira et al, 2007) which could be attributed to the greater DMI. However, in this study, milk yield was not different between BBD and CBD in spite of the greater DMI for CBD.…”