Kenyon P R, Morel P C H, Morris S T, West D M
Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand.
N Z Vet J. 2005 Oct;53(5):340-3. doi: 10.1080/00480169.2005.36571.
To determine the effects of liveweight (LW) and use of teaser rams prior to mating on both the mating performance and pregnancy rate of ewe hoggets.
Romney hoggets (n=841) were weighed and randomly assigned to one of two treatment groups; either exposed to seven harnessed, vasectomised (teaser) rams for 17 days prior to the breeding period (n=283); or not exposed to teaser rams (unteased, n=558). Harnessed Perendale rams were then introduced for two oestrous cycles. Using crayon marks, hoggets were identified as having been mated during the first 17 days only, during the second 17 days only, during both periods, or not mated. All mated hoggets were then scanned for pregnancy using ultrasound, 48 days after the end of the breeding period, and identified as being either non-pregnant, or as single-, twin or triplet-bearing.
Hoggets mated in either the first 17 days only or in both the first and second 17-day periods were heavier than those mated in the second period only (p<0.001). Those mated in the first or second 17-day period only, and those mated in both periods were all heavier prior to mating than those not mated at all (p<0.001). Twin-bearing hoggets were heavier than both their single-bearing and non-pregnant counterparts (p<0.001). A greater proportion of the teased hoggets were mated in the first 17 days only compared with unteased hoggets (62.6 vs 32.1%; p<0.001). In contrast, more of the unteased hoggets were marked in the second 17-day period only (p<0.001). A greater proportion of mated, unteased hoggets were found to be non-pregnant in comparison to their teased counterparts (17.8 vs 11.2%; p=0.02).
Heavier hoggets at breeding were more likely to be mated in the first 17 days of the breeding period and more likely to be twin-bearing. Use of teaser rams for 17 days prior to the breeding period increased the proportion of hoggets mated in the first 17 days, increased conception rates, and thus increased the proportion of pregnant hoggets. These results indicate that farmers should utilise teasers for 17 days prior to commencement of the breeding period and avoid mating hoggets that weigh below 36 kg.
确定体重（LW）以及配种前使用试情公羊对周岁母羊配种性能和妊娠率的影响。
对841只罗姆尼周岁母羊称重，并随机分为两个处理组；一组在繁殖期前17天接触7只佩戴挽具的输精管结扎（试情）公羊（n = 283）；另一组不接触试情公羊（未试情，n = 558）。然后引入佩戴挽具的佩伦代尔公羊进行两个发情周期的配种。使用蜡笔标记，将周岁母羊确定为仅在第一个17天内配种、仅在第二个17天内配种、在两个时期都配种或未配种。在繁殖期结束48天后，对所有已配种的周岁母羊进行超声妊娠扫描，并确定其未怀孕、怀单胎、双胎或三胎。
仅在第一个17天内配种或在第一个和第二个17天期间都配种的周岁母羊比仅在第二个时期配种的周岁母羊体重更重（p<0.001）。仅在第一个或第二个17天期间配种以及在两个时期都配种的周岁母羊在配种前比根本未配种的周岁母羊体重更重（p<0.001）。怀双胎的周岁母羊比怀单胎和未怀孕的周岁母羊体重更重（p<0.001）。与未试情的周岁母羊相比，试情周岁母羊中仅在第一个17天内配种的比例更高（62.6%对32.1%；p<0.001）。相比之下，更多未试情的周岁母羊仅在第二个17天期间被标记（p<0.001）。与试情的周岁母羊相比，未试情且已配种的周岁母羊中未怀孕的比例更高（17.8%对11.2%；p = 0.02）。
繁殖时体重较重的周岁母羊更有可能在繁殖期的第一个17天内配种，且更有可能怀双胎。在繁殖期前17天使用试情公羊可提高周岁母羊在第一个17天内配种的比例，提高受孕率，从而增加怀孕周岁母羊的比例。这些结果表明，养殖户应在繁殖期开始前17天使用试情公羊，并避免让体重低于36公斤的周岁母羊配种。
