Milk progesterone samples in identifying cycling dairy cows

The purpose of this study was to determine the optimal interval between 2 consecutive milk progesterone samples for the detection of cyclicity in dairy cows. Two hundred and thirty-six postpartum periods were monitored with thrice-weekly whole milk progesterone assay. Cyclicity was determined from elevation of the progesterone level. Animals which had started to cycle by 50 or 60 days post partum were included in the study. The last of the 2 samples was taken at 50 or 60 days post partum, respectively.The lowest percentage of false diagnoses (9.0%) in cows which had started to cycle by 50 days post partum was obtained when the samples were taken at 8 days’ interval. In cows which had started to cycle by 60 days post partum the lowest percentage of false diagnoses (1.1%) was obtained when the samples were taken at 10 days’ interval.     

Post-partum ovarian activity in Finnhorse mares with special reference to seasonal effects.

In a previous study, times from parturition to the first ovulation were followed in 55 Finnhorse mares on the basis of milk progesterone determinations. Ninety-six per cent of mares had ovulated by day 20 post-partum. If intervals of more than 19 days are excluded from the data, the time from parturition to 1st ovulation was 117 days. However, in cases of foaling before and after the beginning of June the times were 13.0 days and 8.8 days, respectively (p less than 0.001). Long intervals (over 16 days) occurred mainly before 1st May (in 6 out of 7 cases). In a 2nd study, 25 post-partum Finnhorse mares were examined by rectal palpation and ultrasonic scanning. Five and 7 days post partum, but not 2 days post partum there was a statistically significant difference between ovulatory ovaries and non-ovulatory ovaries regarding size of whole ovary and the largest follicle. Six to 8 days before the first post-partum ovulation, the size of the preovulatory follicle was greater in mares which had foaled before the middle of May (32 mm) than in those which had foaled after the middle of May (20 mm) (p less than 0.05). Within 2 days before ovulation there was no statistical difference between the sizes (43 mm and 42 mm, respectively). The growth rate was therefore slower in cases of early foaling (1.8 mm/day) than in cases of late foaling (3.7 mm/day).     

Onset of luteal activity in non-foaling mares during the early breeding season in Finland.

The luteal activity in mares was studied in the Equine Research Station (ERS) and in trotting stables (TS) in South-Finland. The mares were Standardbreeds in the TS and mainly Finnhorses in the ERS. Between January and June blood was collected once a week for serum progesterone determinations. The mares in the ERS were distributed in 1 of 3 groups: three-years old not yet in training (N = 38), brood mares (N = 21) and mares in training (N = 47). A 4th group was the mares in training in the trotting stables (N = 73). Every 5th mare in the ERS and every 4th mare in the trotting stables were cycling already at the beginning of the year. Onset of luteal activity in anoestrous mares was most common in the middle of May. Over 95% of the mares were cycling at the beginning of June. In the ERS 40% of the Finnhorse mares in training were cycling through the winter. The three-years old and the brood mares were all anoestrous during winter. They started to cycle on average before the middle of May. Anoestrous training mares started before the middle of April. Anoestrous Finnhorse mares began to cycle later than warm blooded mares in all of the groups studied. Mares which had foaled the previous year were more often anoestrous during the winter than dry mares. The time of year when cycling began in a particular mare tended to be the same from year to year (p less than 0.01).     

Pregnancy Rate in Zebu Cows with Two Different Postpartum Intervals Exposed to a Two-Bull Rotational System

In order to evaluate the reproductive effect of a rotational breeding system, the pregnancy rate of 69 Zebu cows was assessed, 32 late postpartum (211±93 days postpartum, LP) and 37 early postpartum (averaging 63±8 days after calving, EP). In the LP group, 60% (19/32) were cycling before exposure to the bulls but only 38% (14/37) in the EP group. The two groups were dissimilar from the start (p<0.05). The cows were exposed in a rotational breeding system, with six Brahman bulls with previous sexual experience paired off in three groups (A–B, C–D and E–F). The cows were exposed to each pair of bulls for a period of 3 weeks, with one week in between each period, when the females were without the presence of a male. In the LP group, the pair of bulls A–B obtained a pregnancy rate of 72% (23/32), whereas for bulls C–D the pregnancy rate was 33% (3/9) and for bulls E–F the pregnancy rate was 67% (4/6). In contrast, for the EP cows, bulls A–B obtained a pregnancy rate of 32% (12/37), bulls C–D a pregnancy rate of 67% (12/18) and for bulls E–F a pregnancy rate of 55% (6/11). The percentage pregnancy obtained using the pair of bulls A–B differed (p<0.05) between LP and EP, whereas for bulls C–D and E–F it was similar. The pregnancy rate was different (p<0.05) in the first 3 weeks of mating for the LP group, the highest number of cows becoming pregnant during the first 3 weeks of the study. In contrast, the highest number of pregnancies in EP occurred evenly during the last 6 weeks. This study suggests that the reproductive performance of pairs of bulls in a 9-week rotational programme with the overall pregnancy rate is similar (94% in the LP and 81% in the EP). However, the time taken for the females to become pregnant, and hence the performance of the bulls, is related to the average number of days postpartum for the cows.     

乏情季节诱导山羊同期发情的研究

通过对云阳县栖霞乡放牧 +舍饲条件下的经产母羊 3组 (A组 40只、B组 3 1只、C组 18只 )共 89只分别用孕激素阴道栓同期发情处理 10天 ,其中A组取栓后直接观察发情情况、B和C组取栓后分别注射PGF2α 0 0 5mg/只和 0 1mg/只。结果表明 :A组 2～ 4天内同期发情率为 42 5 0 % ;B组同期发情率为 67 74% ,48小时有羊只发情高峰 ;C组同期发情率为83 3 3 %。取栓至开始发情时间A组明显长于B组和C组 (P <0 0 5 ) ;平均发情持续时间短于B、C组 (P <0 0 1,P <0 0 5 ) ,B、C组之间差异不显著 (P >0 0 5 )。     

The Effects on Reproductive Performance in the Short and Medium Term of the Combined Use of Exogenous Melatonin and Progestagen Pessaries in Ewes with a Short Seasonal Anoestrous Period

Three hundred and sixty-one adult Rasa Aragonesa ewes were used to evaluate the effect on their reproductive parameters of melatonin implants used in association with the classical synchronization treatment (progestagen plus pregnant mare serum gonadotrophin (PMSG)) in an accelerated breeding system (3 lambings in 2 years). The animals were divided into four groups on the basis of body condition score (H, 2.75; L, 2.5) and treatment (M) or no treatment (C) with a subcutaneous implant containing 18 mg of melatonin on 17 February 1997. Intravaginal pessaries containing 30 mg of fluorogestone acetate were inserted into all the ewes between 3 and 13 March and 500 IU PMSG was injected intramuscularly when the pessaries were withdrawn 14 days later. Fertile rams were introduced on 17 March. The pregnancy rate and litter size were unaffected by either melatonin treatment or body condition. The overall fertility at first plus second oestrus was between 76.4% (HC) and 82.8% (HM), and the litter size was between 1.58 (LM) and 1.82 (HC) lambs born per lambing. However, melatonin did seem to have a positive effect on the reproductive parameters of non-pregnant ewes at the second mating period 2 months later. Finally, no detrimental effect of melatonin implants on fertility and litter size was recorded in the medium term.     

Experimental lead-poisoning in dogs

Extract

It has long been established that antibodies to the major anaerobic infections in sheep are transferred to the suckled lamb in the colostrum or first milk. Effective absorption of such antibodies from the gastro-intestinal tract takes place during the first fifteen hours of life; hence, in order to acquire protection the lamb must have suckled during this period. The degree of protection available in the colostrum will depend on the success of the immunization procedures in the ewe.     

不同时间引入公羊对非繁殖季节诱导卡拉库尔母羊同期发情的试验

将90只处于乏情期的卡拉库尔母羊随机分为两组,统一使用孕激素合剂处理与阴道海绵孕酮埋植12d和肌注PMSG,对两组母羊在不同时间引入处理公羊。结果表明,发情前2d引处处理公羊组97.8%母羊表现发情,第1和第2情期产羔母羊数占处理母羊数的93.3%,其中第1情期产羔母羊数占处理母羊数的48.9%,产羔的综合效果优于发情当日引入处理公羊组。