| Starter is very important to the early development of calves’ rumen. However,preweaning calves fed only with starter will bring a variety of adverse factors(rumen papillae parakeratosis, etc.) to calf rumen development. The starter supplemented with hay can slow down or even eliminate this situation, to promote a more healthy and rapid development of the rumen of calves. Thus, on the basis of giving nursing calves fed starter diet, in order to insure the suitable period adding hay to calves’ diets and promote the healthy development of the calf rumen, one experiment was conducted to evaluate the performance and rumen development of calves by measuring the average daily gain, feed intake, body measurement indexes, animal behaviors, rumen fermentation parameters and slaughter indicators.Experimental design is as follows. The hay source of this experiment is oat hay.Eighteen male Holstein calves(one was to be eliminated due to the long-term diarrhea)(about 40 kg of birth weight) were randomly distributed in 3 treatments. Three dietary treatments were as follows:(1) control(MS) =starter only(MS);(2) MSO2= starter supplemented oat grass in the second week;(3) MSO6= starter supplemented oat grass in the sixth week. All calves were housed in individual pens bedded with sandy soil until 9 wk of age. They were given ad libitum access to water and starter throughout the experiment and were fed 2L of milk twice daily. Calves were weaned at 63 d of age. Dry matter intake of starter and hay and diarrhea events was recorded daily. BW and body measurement indexes were recorded before the morning feeding every two weeks. A rumen sample was taken every two weeks after the morning feeding to determine rumen pH and volatile fatty acid concentrations. And also, blood samples were drawn 2-3 h after the morning concentrate offer to determine serum glucose, insulin and BHBA concentrations every two weeks. Behavior was monitored by direct observations for all of animals within treatment. Animals were observed for 1 h immediately following the morning milk feeding and one additional hourafter solid feed was weighed and offered during the 5 days before preweaning. At the end of experiment, animals were euthanized and each anatomical part of the GIT was separated and weighed with and without contents, and rumen wall samples were collected. Feeding of forage was found to increase total dry matter intake, starter dry matter intake, and final weight(P<0.01); the average daily gain in MSO2 calves was significantly higher than that of the other two groups(P<0.05); and, animals in all three groups was significantly increased with the age(P<0.05). Almost all the three group of calves had no diffience among body measurement indexes in all ages; and all the body index was significantly increased with the age(P<0.01). Calves in group MSO6 have lower serum BHBA concentrations than calves in group MS and MSO2(P<0.05). Compared with MS calves, animals in MSO2 and MSO6 treatments spent more time ruminating(P<0.01)with odds ratios(OR) of 2.63 and 2.02,respectively; and calves consuming forage devoted less time performing nonnutritive oral behaviors(P<0.05)(OR: 0.71 and 0.75, respectively). Calves supplemented with hay or not,had no significant different on diarrhea rate(P>0.05). The calves supplemented with forage tend to have higher rumen pH and there were no significant difference at TVFA concentrations among treatments. Rumen pH and TVFA concentrations were significantly reduced(P<0.01) and increased(P<0.01), respectively, with increasing age. EBW,expressed as a percentage of BW, total GIT weight and gastric tissue tended to be greater(P<0.05) in MSO2 compared with the other 2 treatments. There was no significant effect on rumen volume observed in all three treatments. But calves in MSO2 had the largest rumen volume numerically; followed by group MSO6, and group MS minimum(8.1L, 7.4L and5.8L respectively). Calves supplemented with oat hay had lower(P<0.05)rumen papillae width and epithelial thickness compared with MS calves. And we found that morphometric parameters of the rumen wall substantiated the effect of hay supplementation, as plaque formation decreased macroscopically.In conclusion, supplementing oat hay enhanced the DMI of calves, increased Ruminating behavior and decreased nonnutritive oral behaviors. And calves supplemented with oat hay have a better and healthy rumen environment than calves offered no forage. As show in the results, calves offered oat hay at the second week may be have better performance and rumen development than calves in MSO6. |
PDF Full Text Request