【作者】 张骞；

【导师】 赵国琦；

【作者基本信息】 扬州大学 ， 动物营养与饲料科学， 2010， 硕士

【摘要】 本文以研究不同水平苜蓿干草的TMR中peNDF对奶牛生产性能的影响为主要目的,包括以下三部分试验:试验一选用3头体况良好、平均体重为550±50kg、安装永久性瘤胃瘘管的中国荷斯坦奶牛,采用3×3拉丁方试验设计,以苜蓿干草不同切割长度(1cm、3cm和5cm),在18%(DM基础上)的添加水平下配制3种TMR饲喂奶牛,研究日粮中peNDF水平对奶牛瘤胃发酵的影响。结果表明:提高日粮peNDF水平,奶牛瘤胃pH升高,NH3-N浓度、总挥发性脂肪酸产量及其组成成分随日粮peNDF水平升高而增加,但乙酸/丙酸值下降,其中丙酸含量3cm和5cm组较1cm组均显著增加(p<0.05),5cm组较1cm组丁酸含量显著升高(p<0.05)。试验二选择21头不同胎次(第一和第二胎次各9头,第三胎次3头)处于泌乳中期的中国荷斯坦奶牛,采用3×3拉丁方设计,在3个苜蓿干草切割长度(1cm、3cm和5cm)和3种添加水平(9%、18%和27%,DM基础上)下配制9种TMR饲喂奶牛,以研究peNDF水平对采食和产奶性能的影响。结果表明:日粮peNDF水平对三个胎次奶牛DMI均无显著影响(p>0.05),NDFI、ADFI和peNDFI1.18均随peNDF水平升高而增加,且第一胎次苜蓿干草添加水平为9%时,5cm组和1cm组NDFI、3cm组和1cm组ADFI、3cm和5cm两组和1cm组peNDFI1.18均有显著差异(p<0.05),5cm组ADFI较1cm组极显著提高(p<0.01);添加水平为18%和27%时,5cm组与1cm组ADFI均有显著差异(p<0.05),18%时,5cm组与1cm组peNDFI1.18差异极显著(p<0.01)。第二胎次,添加水平为9%时,5cm组和1cm组NDFI差异显著(p<0.05),1cm组ADFI与3cm组差异显著(p<0.05),与5cm组差异极显著(p<0.05),3cm和5cm组peNDFI1.18较1cm组显著增加(p<0.05),添加水平为27%时,1cm组ADFI也较3cm组显著降低(p<0.05),且与5cm组差异极显著(p<0.01),5cm组和1cm组peNDFI1.18差异显著(p<0.05)。第三胎次,5cm组和1cm组NDFI、peNDFI1.18差异显著(p<0.05)。日粮peNDF水平对三个胎次奶牛产奶量影响均不显著。第一胎次,9%添加水平下,乳脂率和总固体3cm组较5cm组显著提高(p<0.05),27%时,3cm组尿素氮含量较5cm组显著上升(p<0.05)。试验三选用3头体况良好、平均体重为550±50kg的中国荷斯坦奶牛,安装永久性瘤胃瘘管,采用尼龙袋法和扫描电镜技术研究紫花苜蓿茎、叶瘤胃动态降解过程,以研究瘤胃微生物在不同时间点对紫花苜蓿茎、叶的消化作用。结果表明:6h内,瘤胃微生物在苜蓿茎叶气孔周围大量附着,6h后苜蓿叶片叶肉的栅栏组织被快速降解,并在12h后消失。苜蓿茎表皮破裂后,薄壁组织、厚角组织、韧皮部和形成层被快速降解,髓在24h消失,48h时主要为初生木质部和木质部,72h后以木质部为主,瘤胃微生物降解部位依次为表皮和髓、薄壁组织、韧皮部、厚角组织、形成层、初生木质部、木质部。更多还原

【Abstract】 The study was conducted to investigate the effects of physically effective neutral detergent fiber (peNDF) of diffferent levels containing alfalfa hay in total mixed ration (TMR) on the production of cows, which contained 3 experiments.In experiment 1, we studied the effects of peNDF of alfalfa hay on rumen fermentation in cows fed with TMR. Three healthy Chinese Holstein cows with the average weight of 550±50 kg were fitted with permanent rumen cannulas and used as experimental animals in the experiment, which were arranged into a 3×3 Latin Square. The alfalfa hay with different lengths ( 1cm, 3cm or 5cm ) was added in TMR and the weight of alfalfa hay accounted for 18% of the total ration ( dry matter basis ). Results showed that with the increasing of peNDF levels, the rumen pH, NH3-N concentration, total volatile fatty acid and fatty acid composition contents were increased and the ration of butyrate to propionate was decreased. The concentrations of propionate of the cows fed with 3cm and 5cm lengths alfalfa hay were significantly higher ( p<0.05 ) than that of those fed with 1cm. The contents of butyric acid in the group fed with 5cm length alfalfa hay was significantly higher than 1cm ( p<0.05 ).The objective of the experiment 2 was to investigate the effects of peNDF levels on the feed intake and milk performance of dairy cows. Total of twenty-one Chinese Holstein mid-lactating cows were selected as experimental animals. The parity of selected cows was 1 ( 9 cows ),2 ( 9 cows ) and 3 ( 3 cows ), respectively. A 3×3 Latin Square design was used to study the effects of different lengths ( 1cm、3cm or 5cm ) and addition levels ( 9%, 18% and 27%,DM basis ) of alfalfa hay on the feed intake and milk performance of dairy cows. Results showed that dry matter intake ( DMI ) was not significantly affected ( p>0.05 ) by levels of peNDF in the diets for all treatments. NDFI, ADFI and peNDFI1.18, were linearly increased with increasing dietary peNDF. While the level of addition was 9%,intake of NDF was significantly different between 5cm group and 1cm of primiparous cows ( p<0.05 ). The same consequence also was found peNDFI1.18 of 3cm and 5cm group ( p<0.05 ), comparing to 1cm, as well as ADFI of 3cm and 5cm group ( p<0.05, p<0.01, respectively). Both 18% and 27%, ADFI of 5cm group increased compared with 1cm significantly ( p<0.05 ), and intake of peNDF1.18 was very significant when the level of addition was 18% ( p<0.01 ). To the second parity, NDFI of 5cm group increased significantly compared with 1cm ( p<0.05 ), Intake of ADF was significantly difference between 1cm group and 3cm, Furthermore, compared with 5cm, 1cm group descended very significantly ( p<0.01 ), for peNDFI1.18, both 3cm and 5cm group were more than 1cm group ( p<0.05 ) as 9%. Additive level was 27%, ADFI of 1cm group also breakdowned compared with 3cm and 5cm group ( p<0.05, p<0.01, respectively), while peNDFI1.18 was significant between 5cm and 1cm group. Compared with 1cm, NDFI of 5cm group improved significantly, as well as peNDFI1.18 ( p<0.05 ) for the thrid parity. However, dietary peNDF did not significantly improve milk production. AS 9%, compared with 5cm group, fat and totle solid in milk of 3cm group raised significantly ( p<0.05 ), meanwhile, the content of Urea nitrogen had the same trend when the level of addition was 27% ( p<0.05 ).In experiment 3, three healthy Chinese Holstein cows with the average body weight of 550±50 kg were fitted with permanent rumen cannulas and used as experimental animals to study the degradability of the stem and leaf of alfalfa in rumen with the technology of nylon bag and scanning electron microscopy technique. The results showed that ruminant microflora attached to the epidermis of the stem and leaf around stoma within 6h. Palisade of mesophyll was rapidly degraded within 6h and then veins and spongy tissue were exposed. After 12h of fermentation, the leaf completely disappeared. Alfalfa stem epidermis was broken alfter 12h, and parenchyma, collenchyma, phloem, cambium and pith were totally degraded within 24h. After 48h, only the primary xylem and xylem-based were left. After 72h, the only undegradation part is xylem. The turn of the digestive order are skin and pith, parenchyma, phloem, collenchyma, cambium, primary xylem, xylem.更多还原