Research And Extension On Crossbreeding Improvement Technology Of Xiangxi Yellow Cattle

Xiangxi yellow cattle a favorable local breed in Hunan Province of China. However, theperformance of Xiangxi yellow cattle can not meet requirement as beef cattle because of longhistory of working draft and should be improved. This study was undertaken to discussapplication of artificial insemination (AI) with frozen sperm and the crossbreeding effects of theXiangxi yellow cattle. The main results were as follows:In an attempt to promote the application of the technology of frozen semen insemination tocrossbreed Xiangxi yellow cattle, it was carded out to examine the effects of extender solution ofsemen cryopreservation, casing-form of cryopreserving semen, estrus synchronization, newinseminated appliances and simple fixing equipment. The results indicated that the extender 1and 3 were favorable one among the three extender solutions of semen cryopreservation, inwhich there were 34%—35% and 17%—18% of A and B class sperm with forward motilitydetermined by computer-assisted semen analysis (CASA), respectively. Frozen semen in strawwas convenient to thawing, not easy to be contaminated and able to improve the fertility with94.2% total pregnancy rate, compared to pelleted frozen semen. Although estrus rates aftertreatments of estrus synchronization did not show significant difference among 3 treatmentgroups (P＞0.05), but the pregnancy rate (50%) of estrus cows in the groupⅠwas higher thanthose in other 2 groups (P＜0.05) remarkably. The new inseminated appliances and the simplefixing equipment, which were convenient to manipulate in practice, had adapted well toapplication under the condition in villages. After application of straw frozen semen andcorrelative techniques the number of cows inseminated with straw frozen semen. 11370 Xiangxi yellow cattle has been improved from 2003 to 2004, which promoted progresses in improvementof the Xiangxi yellow cattle through crossbreeding.Crossbreeding effects of Xiangxi yellow cattle fed in villages were observed. The bodyweight and body sizes of crossbreds F1 of Xiangxi yellow cattle with beef breeds Simmental,Angus, Shorthorn, Limousin at newborn, 6-month, 12-month and 24-month old were measured.The results showed that the body weights of all types of crossbred F1 at all ages up to 24 monthswere increased significantly (P＜0.05) compared to Xiangxi yellow cattle. The body weights atnewborn were increased 51.42% in Simmental F1, 47.29% in Limousin F1, 31.19% in ShorthornF1, 18.62% in Angus F1; the body weights at the age of 6 months increased 75.28% in Angus F1,67.11% in Simmental F1, 43.90% in Shorthorn F1 and 40.84% in Limousin F1; at the age of 12months increased 36.76% in Simmental F1, 33.19% in Angus F1, 26.65% in Limousin F1 and23.43% in Shorthorn F1; at the age of 18 months increased 38.64% in Simmental F1, 32.26% inShorthorn F1, 29.83% in Limousin F1 and 22.50% in Angus F1; at the age of 24 monthsincreased 57.89% in Simmental F1, 43.21% in Limousin F1, 41.64% in Shorthorn F1 and27.12% in Angus F1. The main body sizes as heart girth, body length, height at withers andcircumference of cannonbone at all ages were also increased significantly (P＜0.05). The heartgirth, body length, height at withers and circumference of cannonbone of the crossbreed F1 at6-month old increased 9.06%-19.3%, 18.16%-23.92%, 8.50%-13.06%, 24.76%-34.02%,respectively; at 12-month old increased 3.55%-8.48%, 6.31%-8.87%, 6.60%-10.85%,7.91%-11.72%; 18-month old increased 11.05%-17.74%, 7.22%-15.22%, 4.50%-12.58%,6.82%-11.22%: 24-month old increased 8.64%-14.16%, 9.14%-15.85%, 8.52%-13.38% and5.95%-13.51%. The results suggest that the growth performance of crossbred F1 in varioushybrid combinations is improved and has brought economic benefit of 42.5% compared toXiangxi yellow cattle.