An Investigation of a Repeat Breeder Problem in Dairy Cows

Patel, Osman Valli (1990) An Investigation of a Repeat Breeder Problem in Dairy Cows. MVM(R) thesis, University of Glasgow.

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Repeat breeding in dairy cows is still a major problem and causes substantial economic loss through increase in calving interval and reduction in milk yield. Although factors related to the bull and the environment have been implicated, the majority of the research has shown that the cow plays a major part in the repeat breeding syndrome. Since Lindhal (1966) first reported the use of ultrasonography in detection of pregnancy in sheep, the technique has gained popularity in veterinary medicine as a diagnostic aid. However, due to the additional equipment cost compared to rectal palpation, it has rarely been used on a commercial basis for diagnosis of reproductive disorders in cows. The purpose of this study was to compare the reproductive events in normal and repeat breeder cows using ultrasonography and plasma progesterone concentration. Cows were divided into two groups and were bled and scanned regularly. Group one consisted of normal cows and group two consisted of repeat breeder cows. The cows that conceived in both groups were observed from day of insemination up to day 42 post-insemination whereas those that did not conceive were only observed till they returned to service again. All the cows in group one and two cows from group two conceived, though one of the repeat breeder cows had lost an earlier conceptus but held to the next service. One cow from group two lost the conceptus and developed a luteal cyst during the period of observation. Three other cows from group two did not conceive. Two of them returned to service between day 20 and day 23 while the third cow was not seen on heat by the herdsman during the period of observation. In the pregnant cows, the area, height and width of the corpus luteum, as measured by ultrasound, fluctuated throughout the period of observation but the plasma progesterone concentration remained elevated. In the cows that did not conceive, the corpus luteum, as seen by ultrasound, reduced in size, decreased in echogenicity and its outline became blurred as the next oestrus drew nearer. In addition, in these cows the plasma progesterone concentration declined rapidly and reached basal levels as the next oestrus approached. More follicular activity was evident in non-pregnant cows than in pregnant cows. In the pregnant cows the ovary contra-lateral to the corpus luteum bearing ovary showed more follicular activity. The uterus in oestrus, dioestrus and pregnancy was found to exhibit characteristic images. These included a distinct folding of the endometrium and accumulation of intra-uterine fluid during oestrus and lack of folding and fluid during dioestrus. The embryonic vesicle was seen as early as day 13 in the pregnant cows and the embryo proper was detected by day 20. This study demonstrated that ultrasonography in collaboration with plasma progesterone concentration was useful in monitoring the reproductive events in both normal and repeat breeder cows. Although additional cost of the equipment currently precludes the complete replacement of bovine rectal palpation by ultrasound, ultrasonography can augment rectal palpation and endocrinology in individual animals that present diagnostic problems. Further studies are needed to confirm, clarify and extend the findings reported and to justify the commercial use of ultrasonography in monitoring herd fertility.

Item Type: Thesis (MVM(R))
Qualification Level: Masters
Keywords: Animal sciences, Veterinary science
Date of Award: 1990
Depositing User: Enlighten Team
Unique ID: glathesis:1990-78080
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 28 Feb 2020 12:09
Last Modified: 28 Feb 2020 12:09

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