Reproductive Efficiency of Cows of Different Sizes

نویسنده

  • Timothy A. Olson
چکیده

The effect of cow size on reproduction has become of in, respectively. The hip heights of the small, medium greater concern in recent years as a result of marked and large frame-size bulls used were 53, 55 and 57.5 in, increases in cow size in both purebred and commercial respectively, at 2 yr of age. The bulls were selected from herds and the extremely large effect of fertility on the within the STARS herd or were loaned from private profitability of commercial cowherds. This increase in herds. All were of gray Brahman breeding. The cows mature size has come about as a result of the use of large were maintained on bahiagrass pastures, with hay and imported European breeds in crossbreeding programs and protein supplement being fed during the winter months. as a result of selection within the existing British and Bos Heifers were bred for the first time at 2 yr of age. A indicus breeds for mature size. Some of the increase in breeding season of 90 d was used from 1983 through mature size has likely been the result of a correlated 1986 but was lengthened to 120 d in 1987. response to selection for yearling weight, but unfortunately there has been considerable direct selection The weights, heights, reproductive rates and body for mature height and weight as evidenced by the condition scores of females born since 1984 are shown in advertising of the mature weights and heights in breed Table 1. The difference between the hip heights of the journals. Also, it is an unfortunate fact that for many small vs the large frame-size groups of females ranged years there has been a tendency for judges to use height from 2.4 to 3.5 in depending on age. This difference as a major criterion for placement in the showring. While would be slightly less than two frame-size scores based it is perhaps now generally assumed that increased cow on the American system, with the small frame size group size will lead to reduced reproductive efficiency, being about 5 on this system and the large cows being relatively few studies have examined the magnitude of about 7. Age at puberty data from heifers born during differences in cow size that exist in many breeds of cattle the early years of the study have been analyzed by in the United States today. The effect of cow size has Senseman (1989). Heifers from the small frame-size been confounded with breed composition in most of the group reached puberty somewhat earlier -588 d -and studies which have been conducted to date. The purpose at lighter weights -666 lb -than did the large-frame of this paper is to report on results of the effect of cow heifers that reached puberty at an average weight of 754 size on reproduction in the Brahman breed at the Sublb at 635 d of age. The heifers were not exposed to bulls tropical Agricultural Research Station (STARS) near until they were more than 2 yr of age, however, when the Brooksville, Florida, and to review other studies that have majority of the heifers of all frame sizes had reached investigated the effect of cow size within the same breed puberty. As a result, differences in pregnancy or breed cross on reproductive traits. percentages at 2 yr of age were not great -93.7, 89.7

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Productive and Reproductive Potentialities of Different Genetic Groups of Crossbred Cows Reared under Different Farming Conditions

A cross-sectional comparative study was carried out to investigate the productive and reproductive performances of different genetic groups of crossbred cows at three different farming conditions in Bangladesh. Crossbred cows (n=90) those already completed third lactations, were selected randomly from three different dairy farms (e.g. Jarip, Mullah and Nahar) located in Chittagong, Bangladesh. ...

متن کامل

The effect of administration of gonadotropin releasing hormone analogue at estrus or during luteal phase on reproductive performance of dairy cows maintained under sub-temperate climate

Overall, 531 dairy cows were inseminated with the aim to study their reproductive performance following administration of GnRH analogue on different days of estrous cycle with different doses. These cows were divided into six treatment and one control group. Depending upon different treatment groups, Buserelin acetate was injected at a dose of 10.5 µg or 21.0 µg on different days (0, 5 or 12) o...

متن کامل

Delayed Ovarian Cyclicity Does not Reflect Blood Metabolites Irregularity in Postpartum Holstein Cows

An experiment was conducted to investigate the effect of different types of ovarian cycles on reproductive indices and blood metabolites in 61 Holstein cows. Blood samples were taken from each cow between day 12 and day 50 postpartum (PP). Serum progesterone concentrations were measured to determine the onset of luteal function and different types of luteal dysfunctions in cows. Serum glucose, ...

متن کامل

The effect of Zataria multiflora extract on the clinical endometritis and reproductive indices in lactating Holstein dairy cows

In the present study, the effect of intrauterine infusion of Zataria multiflora extract on the clinical endometritis was investigated. Vaginal examination, transrectal palpation and ultrasonography were used to inspect the genital tract at 30-40 days in milk and two weeks later the same approach was applied. Cows with clinical endometritis were randomly divided into three treatment gro...

متن کامل

Recent studies on nutritional factors affecting reproductive efficiency in U.S. dairy herds

Reproductive efficiency is declining on U.S. dairy herds. There are numerous factors that affect reproductive efficiency on individual farms. These include heat detection rate, heat stress, semen quality, bull fertility, AI technique, nutrition, body condition score, clinical and subclinical mastitis, cow comfort, and many other factors related to whole farm management, individual farm managers...

متن کامل

O-11: Immunoneutralization of Inhibin Alpha Subunit as A Tool for Improving Farm Animal Fertility

Background: The objectives of a series of studies undertaken was to improve farm animal reproductive efficiency in terms of embryo production efficiency, conception rate and litter size by immunoneutralization of inhibin in conjunction with other conventional reproductive techniques. Materials and Methods: A recombinant porcine inhibin alpha-subunit mature peptide was produced by mass scale and...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 1997