Effect Of Different Milk Allowances And Different Starter On Gastrointestinal Development Of Dairy Calves

Traditional starter concentrates for dairy calves are rich in easily fermentable starch to initiate rumen short-chain volatile fatty acid(SVFA) production and to stimulate ruminal development. However, SVFA production in young calves may cause decrease in rumen pH and induce subacute rumen acidosis(SARA). When we used low-starch, high-fiber,high-molasses concentrate to replace traditional high-starch concentrate, it may prevent SARA and may had no effect on growth and reticulorumen development. When milk is reduced,the intake of solid feed will be increased. But effect of low milk allowance on rumen papillae development hasn't been certain. And little work has specifically addressed differences in rumen papillae development. Therefore, the objective was to study the effect of different concentrate and different milk allowances on growth and gastrointestinal development in preweaned dairy calves.Sixteen newborn Holstein male calves were allocated to four groups equally as follows.(1) A experimental low-starch, high-fiber, high-molasses concentrate(EXP) was fed at a high whole milk allowance(6L/d);(2) A traditional high-starch concentrate(TRA) was fed at a high whole milk allowance(6L/d);(3) A experimental low-starch, high-fiber, high-molasses concentrate(EXP) was fed at a low whole milk allowance(3L/d);(4)A traditional high-starch concentrate(TRA) was fed at a low whole milk allowance(3L/d). EXP contained 21% starch,28%NDF, 10% molasses and TRA contained 40% starch, 14%NDF, 5% molasses. All calves had free access to grass hay and water. Body size and body weight were measured at 0wk,2wk, 4wk, 6wk, 8wk and 60 d respectively. Dry matter intake(DMI) was measured daily.Three calves were selected from per group and were euthanized at 60 days.In the study,DMI of concentrate and total DMI were higher for low milk allowance compared with high milk allowance,whereas withers height at 4wk,heart girth at 6wk, daily gain during 2wk to 4wk and daily gain during 4wk to 6wk were lower(P<0.05). There was no difference between TRA and EXP in DMI, body size and ADG(P>0.1). Full total stomach weight,full reticulorumen weight,the proportion of full total stomach weight of EBW, full reticulorumen weight of EBW, small intestine length, full small intestine weight, the proportion of full small intestine weight of EBW, and papillae length in ventral rumen sac laterally were higher for low milk allowance compared with high milk allowance(P<0.05),reticulorumen volume tended to be higher(0.05<P<0.1),whereas papillae length in ventral rumen sac ahead and jejunum villus width was lower(P<0.05). Full total stomach weight, the proportion of full total stomach weight of EBW, empty reticulorumen weight,full abomasum weight,the proportion of full abomasum weight of EBW,reticulorumen volume were lower for EXP compared with TRA(P<0.05), but mall intestine length, full small intestine weigh,the proportion of full small intestine weight of EBW,acetate concentration and rumen pH were higher(P<0.05). There was no difference between TRA and EXP in intestinal villus development(P>0.1), and there was interaction between milk allowance and type of concentrate in papillae development in dorsal rumen sac.In general, calves fed EXP had higher pH and same growth performance. And EXP had no effect on papillae development in ventral rumen sac, increased small intestine length, but reduced the weight of reticulorumen. Low milk allowance had a positive effect on papillae development in ventral rumen sac laterally and a negative effect on papillae development in ventral rumen sac ahead. Low milk allowance slightly promoted reticulorumen development.