Comparison of hull-less barley, barley, or corn for lactating cows: effects on extent of digestion and milk production.
Six lactating, cannulated Holstein cows were used in a double 3 x 3 Latin square design to compare the effects of hull-less barley with barley and corn on ruminal fermentation, rate of passage, flow of nutrients to the duodenum, and milk production. Diets consisted of 60% concentrate, 30% barley silage, and 10% alfalfa hay (dry matter basis). Concentrates contained steam-rolled grains: hull-less barley, barley, or corn. Dry matter intake was unaffected by grain source, but starch intake tended to be greatest when hull-less barley or corn was fed. The barley diet was more degradable in the rumen than was the hull-less barley or corn diet, and, therefore, flow of microbial organic matter to the duodenum was greatest for cows fed the barley diet. Flow of microbial N to the duodenum was greater (50 g/d) for cows fed the barley diet than for cows fed the other diets, and the flow of ruminally undegradable N was greater (43 and 28 g/d) for cows fed the hull-less barley and corn diets, respectively, than for cows fed the barley diet. As a result, flow of nonammonia N to the duodenum was unaffected by grain source. Total tract apparent digestibility was highest for cows fed the barley and corn diets. Despite its low digestibility, cows fed the hull-less barley diet produced a similar amount of milk as did cows fed the barley and corn diets. Further studies are needed to evaluate the effects of processing hull-less barley on its utilization by dairy cows.
Yang
W Z
WZ
Livestock Sciences Section, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada.
Beauchemin
K A
KA
Koenig
K M
KM
Rode
L M
LM
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001419:Bacteria / Q000378:metabolism; D002417:Cattle / Q000502:physiology*; D004063:Digestion; D004386:Duodenum / Q000378:metabolism; D005260:Female; D005285:Fermentation; D001467:Hordeum; D007774:Lactation / Q000502:physiology*; D008892:Milk / Q000737:chemistry; D009584:Nitrogen / Q000378:metabolism; D012417:Rumen / Q000378:metabolism / Q000382:microbiology; D003313:Zea mays
D009584:Nitrogen