| Experimental animals were randomly assigned into MS and MSA group. Calves in MS group were feed milk and starter, and feed milk, starter and alfalfa in MSA group. At the age of60d,4calves selected in each group weaned.4slaughter tests were carried in our study, to test the influence of supplementary feeding of alfalfa on the development of rumen and small intestine.Experiment1was conduct to investigate the effect of supplementary feeding alfalfa hay on the growth of calves based on feeding milk and starter. Twenty-four healthy Holstein calves (45±4kg) were randomly assigned to one of two groups, calves (n=12) in MS group were feed milk and starter, other calves in MSA group were feed milk, starter and alfalfa, respectively. Four calves in each group were slaughtered at the age of35d,55d and75d to study the effect on the growth of calves between MS and MSA in terms of body weight (BW), empty body weight (EBW), chest girth (CG), body length (BL) body height (BH), dry matter intake (DMI) and average daily gain (ADG). The results showed that DMI of calves in MSA (1399g/d) was significantly higher (P<0.01) than that in MS group (1211g/d), DMI of calves was improved with the increase of age (P<0.01). ADG of calves in MSA group (646g) was significantly greater (P<0.01) than that in MS group (519g), ADG of calves significantly increased (P<0.01) with the increase of age. The BW and EBW were increased as the extend of age (P<0.01). EBW/BW percentage of calves in MSA group (69%) was significantly lower (P<0.01) than that in MS group (73%). There were no significantly difference on CG, BL and BH between MSA and MS group (P>0.05), CG and BH of calves in MSA group were increased with the prolong of age (P<0.01).Experiment2, twenty-four newborn calves were randomly assigned into1of2groups:with (MSA) or without (MS) alfalfa hay supplementation. All the calves fed the same fresh milk and starter. Starter and alfalfa were offered since5and10d, respectively.4calves of each groups were randomly chose and slaughtered at the age of35,55,75d. Alfalfa supplementation increased the weight of stomach (1951vs.1699g, P<0.05), had the trend to increase the weight of reticulorumen (1175vs.1030g,0.1>P>0.05), but with no significant effect on the ratio of reticulorumen to stomach weight (p>0.05); increased the weight of stomach digesta (7.7vs.4.4kg, p<0.01) and the ratio of stomach digesta to body weight (9.7%vs.5.7%, p<0.05); improved the ruminal pH (6.24vs.5.80. P<0.0) and acetate concentration (37.55vs.27.93mmol/L, P<0.01), had no significant effect on the concentration of propionate, butyrate and total volatile fatty acids (p>0.05); reduced the height (p<0.05) and width (p <0.05) of ruminal papilla, had no significant effect on the thickness of ruminal muscle layer (p>0.05); increased the length of small intestine (20.8vs.17.1m, P<0.01), reduced the depth of duodenal crypt (p<0.01), had no significant effect on the height of duodenal villus and jejunal villus and the depth of jejunal crypt (p>0.05). In conclusion, alfalfa supplementation was beneficial to increase the volume of stomach and reticulorumen, ruminal pH stability and health, but decreased the height of ruminal papilla, and was beneficial to small intestine development.Abstract:Experiment III was performed to assess the effects of delay weaning and weaned influence on body weight, organ and gastrointestinal development in calves. Eight calves (four in MS group, four in MSA group) in experiment I were used in this study feeding the same ration pattern as in experiment I until75days. And another eight male calves at5day were selected and arranged into two groups according to weight. Feeding pattern of group1:milk+starter (MSWA), group2:milk+starter+alfalfa (MSAW). Calves in the two groups were weaned at60day, and the supplied with alfalfa.. All calves were slaughtered at75d. The results indicated alfalfa supplementation significantly improved daily weight gain, weight of stomach with digesta, and intestinal length extremely (P<0.01), and significant increased (P<0.05) stomach weight, ruminal pH, and acetate concentration, muscle layer thickness of anterior capsule, meanwhile ruminal propionate concentration was significantly reduced (P<0.05). And some unhealthy ruminal development was detected at the same time. However, daily weight gain, weight of stomach with digesta, stomach, rumen and reticulum, ruminal pH and papillae width of anterior capsule in MSAW group were extremely significantly higher (P<0.01) than that of MSWA, and muscle layer thickness of rumen and duodenum were significant increased (P<0.05), as well as the significant decrease (P<0.05) of ruminal propionate and butyrate concentration and intestinal length. Alfalfa supplementation after weaning was not enough to compensate the slow development of rumen caused by shortage of forage before weaning. Overall, alfalfa supplementation could improve the rumen health, and supplementation of alfalfa before weaning is helpful to reduce the weaned stress. |
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