Andersson A M, Einarsson S
Acta Vet Scand. 1980;21(4):677-88. doi: 10.1186/BF03546854.
The object of the investigation was to study a number of gilts during their first six heats in respect of duration and external signs of oestrus in relation to ovarian function. The study comprised 11 crossbred gilts (Swedish Landrace X Yorkshire). Heat control was done twice daily and comprised a careful inspection of the vulva and check of the standing reflex with and without a vasectomized boar. The ovaries were inspected after the first, third and fifth heats by laparoscopy. Blood samples for progesterone determination were taken once a week during the whole observation period. The genital organs were examined after slaughter. All gilts came in heat regularly during the whole period. Reddening and swelling of the vulva were observed during a significantly longer time in the first and second than in the subsequent pro-oestrous periods. The length of oestrus did not vary significantly in successive heats. The duration of the standing reflex was consistently shorter when the heat control was done in the absence of a boar. All gilts had low progesterone values before their first observed heat. The progesterone level in the blood during the five oestrous cycles studied varied in a cyclical pattern. The number of corpora lutea increased from heat 1 to 5.
本研究的目的是观察若干后备母猪在前6次发情期间发情的持续时间、外部表现及其与卵巢功能的关系。研究对象包括11头杂种后备母猪（瑞典长白猪×约克夏猪）。每天进行两次发情检查，仔细观察母猪外阴部并通过有或无输精管结扎公猪检查其静立反射。在第1、3、5次发情后通过腹腔镜检查卵巢。在整个观察期内每周采集一次血样测定孕酮。在屠宰后检查生殖器官。所有后备母猪在整个期间均正常发情。与随后的发情前期相比，外阴部发红和肿胀在第1次和第2次发情时持续时间显著更长。连续发情期间发情持续时间无显著差异。在没有公猪的情况下进行发情检查时，静立反射持续时间始终较短。所有后备母猪在首次观察到发情前孕酮值较低。在所研究的5个发情周期中，血液中孕酮水平呈周期性变化。黄体数量从第1次发情到第5次发情逐渐增加。
