Response of cattle and sheep to hormonal anabolic compounds

Data are presented from a number of experiments which investigated the effect of hormonal anabolic compounds on growth and metabolism in cattle and sheep. The anabolic agents used were trenbolone acetate, hexoestrol oestradiol-17 and zeranol, alone or in combination. Responses to these compounds which were given by implant or injection were studied in bulls, steers, heifers, lactating cows and wether lambs. Particular measurements were made of growth rate, food conversion efficiency, carcase weight and composition and concentrations of blood metabolites and hormones.     

Treatment of cystic ovarian disease in dairy cattle

Fourty-four Holstein Friesian cows diagnosed as having ovarian follicular cysts from rectal palpation of the ovaries and observation of estrous behavior were used for the present experiments. Of the 16 cows injected intramuscularly (i.m.) with 110 mg of depot-progestins containing 100 mg of 17alpha-hydroxyprogesterone caproate and 10 mg of progesterone in oil, 8 cows responded with conception with 103 +/- 53 days in average after the treatment. The 8 cows not responding to depot-progestins were injected i.m. with 6,000 MU of HCG on the 10th day after the treatment. As a result, 2 cows of them conceived within 72 days in average after the initial treatment. Of the other 16 cows injected i.m. with 100 mg of progesteron in oil, 3 cows conceived. Interval between the treatment and conception was 36 +/- 9 days in average. In the 11 cows which failed to respond to progesterone treatment, an intramuscular injection of 6,000 MU of HCG on the 5th day after treatment resulted in conception of 7 cows within 42 +/- 10 days in average after the first treatment. Of the remaining 12 cows which received an i.m. injection with 10,000 MU of HCG, 4 cows responded with conception with 64 +/- 51 days in average after treatment. No remarkable rise in serum progesterone levels was observed either 10 days after depot-progestins injection or 5 days after progesterone treatment. Serum progesteron levels increased distinctly after HCG injections. The combined treatment with 100 mg of progesterone and 6,000 MU of HCG at 5 days interval gave the most successful results and this treatment was effective even when performed long after calving. Thus this method of treatment of cystic ovarian disease may be recommended for practical application.     

Three cases of ovarian epidermoid cysts in cattle

Three cases of bovine, ovarian epidermoid cysts were diagnosed as unilateral benign lesions in three out of 1,971 cows at slaughter. A stratified, cornifying, and squamous epithelium without associated skin adnexal structures or tissues from other embryonic tissue layers lined the cysts. The cysts were small, usually multiple, and contained keratin debris. Macroscopically, they resembled abscesses. These are benign, congenital lesions that are a separate entity from dermoids and teratomas, and they appear to have a higher incidence in cattle with Bos indicus breeding.     

The asymmetric distribution of ovarian functional structures in cattle

The results of continually repeated transrectal palpations, performed in 168 post partum periods, 383 estrous cycles and 178 early pregnancies, were used to describe and to discuss the left-right distribution of ovarian functional structures. In cycling as well as in pregnant cattle, anovulatory interestral follicles and estrous follicles or corpora lutea in the mean were all distributed at 41% and 59% on the left and right ovaries respectively. No signs were found indicating that the position of functional structures would be influenced by local interactions between follicles and corpora lutea. At least for cyclic ovarian activity, and in early pregnancy, the interrelationship observed between the locations of these structures could be put down to the normally increased activity of the right ovary. After delivery, the first follicles preferentially became discernible on the ovary opposite to the previously pregnant uterine horn. But, as from the 4th follicle p.p. onward, the distribution of new ovarian structures again agreed with the one of the ensuing reproductive stages. After calving, probably the position of new follicles is temporally influenced by direct signals from the uterine horns affected differently by pregnancy. Several observations indicate that the factors causing asymmetrical ovarian activity could exert a selective effect on the recruitment of the dominant and solitary interestral follicles from the pool of their minor and less differentiated precursors.     

Comparative evaluation of hormonal protocol on the performance of crossbred cattle

A total of 60 animals (38 cows, 22 heifers) were selected and were divided into three groups of 20 animals each (containing both anoestrus and repeat breeder) in which treatment was performed for 60 days. Group I: control (farmer practice), T₁ group: group I?+?hormone (double synch), and T₂ group: group I?+?hormone (Estra double synch). The growth performances were measured in terms of body weight and average daily gain (ADG). Blood collection was done at the start and end of the experiment for assessment of blood biochemical, hematological, and reproductive status of the animals. Results revealed significant improvement in growth and reproductive performances in treatment group as compared to control group. Higher percentage of conception was achieved in group III (60%) followed by group II (55%). The least percentage was in group I (15%), i.e., in control group. So it was found that the effect of treating the reproductive-disordered animals with Estra double synch gave comparatively better result than double synch hormonal application.     

Factors that affect ovarian follicular dynamics in cattle.

Studies of ovarian follicular dynamics in cattle may lead to methods for improving fertility, for synchronizing estrus with more precision, and for enhancing superovulatory responses. Within an estrous cycle, two or three large (> 10 mm) follicles develop during consecutive waves of follicular growth. The last wave provides the ovulatory follicle, whereas preceding wave(s) provide follicles that undergo atresia. The life span of large follicles seems to depend on the pulsatile secretion of LH; decreased frequency of LH pulses results in atresia of large follicles. Aromatase activity in the walls of the largest follicles is greatest during the first 8 d of the estrous cycle and decreases by d 12. Steroidogenesis of the largest and second-largest ovarian follicles differs on d 5, 8, and 12 of the estrous cycle. Follicular dynamics are altered by negative energy balance and lactation. The number of large follicles and concentration of estradiol during the preovulatory period differs between postpartum lactating and nonlactating cows. Dietary fats stimulate follicular growth when they are fed to increase energy balance. Administration of bovine somatotropin decreases energy balance and has a differential effect on ovarian follicular responses; growth of the largest follicle does not change, but growth of the second-largest follicle is stimulated by somatotropin. Studies of follicular dynamics in lactating cows demonstrate changes in ovarian function associated with energy balance that may be related to inefficient reproductive performance of cows producing high yields of milk.     

Comparison of various examination methods used in ovarian diagnostics in cattle

In this study diagnostic certainty of ultrasonography and rectal palpation concerning the detection of follicles and C.I. was compared by evaluation of the findings obtained with ultrasonography in waterbath and dissection of the ovaries after slaughter. Clinical examinations were performed on a total of 30 cows (transrectally and ultrasonographically, 5.0 mhz, linear) in slaughterhouse. In the laboratory ovaries were evaluated after slaughter both macroscopically and by ultrasonography in waterbath. Diagnostic reliabilities of these methods were compared. No difference between the methods was determined concerning the longitudinal measurements of corpora lutea (19.96 +/- 4.83 mm, 20.41 +/- 5.41 mm, 21.45 +/- 5.26 mm by ultrasonography, waterbath and macroscopy respectively). By means of determining the correct identification of corpora lutea, the error rate was 24.1% and 17.2% for rectal palpation and ultrasonography respectively. The comparison of rectal palpation and macroscopy showed that three small corpora lutea and two corpora lutea with small cavity were determined wrongly as small follicles and two corpora lutea were determined whereas they were not present actually. With ultrasonography four small C.I. could not be detected and one C.I. with cavity was wrongly determined as follicle. It was noticed that follicles bigger than 10 mm (F2 = 10-15 mm, F3 = 16-20 mm) could be determined more accurately by means of ultrasonography than by rectal palpation (with ultrasonography: F2 = 90.48%, F3 = 100.0%; with rectal palpation, F2 = 61.9%, F3 = 200.0%). The correlation of the findings of rectal palpation or ultrasonography and blood progesterone levels was 86.2% and 89.7% respectively. This accordance was 96.6% for progesterone levels and waterbath and macroscopic findings.     

Associations of prepartum body condition score with occurrence of clinical endometritis and resumption of postpartum ovarian activity in dairy cattle

This study was performed to investigate the effect of periparturient body condition score on the occurrence of clinical endometritis and postpartum resumption of ovarian activity in dairy cows. Eighty-seven lactating Holstein cows, fed with a total mixed ration diet, were included into the study. Body condition scoring (using a 5-point scale with quarter-point divisions) was performed by the same investigator using the visual technique every 2 weeks, from 2 weeks before until 6 weeks after calving. Palpation of the reproductive tract and ultrasonographic assessment of ovaries for detection of corpus luteum using a rectal linear probe was also performed at 2, 4, and 6 weeks after calving. Cows with clinical endometritis had significantly lower body condition score (BCS) than normal cows at all weeks pre- and postcalving, and cows that did not ovulate until 45 days after calving had a significantly lower BCS pre- and postpartum. Cows that did not ovulate until 45 days after calving also lost more BCS from 2 weeks before to 4 weeks after calving. Besides, first ovulation after calving take occurred later in cows with clinical endometritis compared to normal cows (P?<?0.05). In conclusion, low BCS is a risk factor for postpartum endometritis and delayed cyclicity in dairy cows. BCS loss from dry-off to early lactation and occurrence of clinical endometritis can significantly affect postpartum ovarian activity.     

Persistent anthelmintic activity of ivermectin in cattle

Two studies are described which demonstrate the persistent activity of ivermectin injected subcutaneously into cattle at 200 micrograms/kg in preventing the establishment of induced infections with the gastrointestinal parasites Ostertagia ostertagi and Cooperia oncophora and the lungworm Dictyocaulus viviparus. These results indicated a reduction in mean worm count compared with the control group for O ostertagi of more than 99, 45 and 94 per cent with a seven, 14 or 21 day interval between treatment with ivermectin and the administration of infective larvae, respectively, in trial 1 and more than 99, more than 99 and 99 per cent at seven, 10 or 14 days, respectively, in trial 2. Corresponding values against C oncophora were 99, 0 and 45 per cent at seven, 14 and 21 days in trial 1 and more than 99, 84 and 31 per cent at seven, 10 and 14 days in trial 2. Against D viviparus, reduction in counts were more than 99, 98 and more than 99 per cent at seven, 14 and 21 days, respectively, in trial 1 and 100, 100 and 100 per cent at seven, 10 and 14 days, respectively, in trial 2. The relevance of these results to the build-up of infective larvae on pasture and infection in cattle is discussed.     

The relationship between oocyte morphology and ovarian status in cattle

We investigated the relationships between oocyte morphology, follicular size and follicular waves using bovine ovaries derived from local abattoirs. Ovaries at the recruitment and selection phases contained larger numbers of oocytes with good developmental ability, although ovaries at the recruitment phase contained the largest numbers of follicles compared with ovaries at the selection and dominant phases. Dominant phase ovaries contained a high percentage of oocytes with as good developmental ability as selection phase ovaries; however, they contained the lowest total number of oocytes with good developmental ability. Small follicles under 3.0 mm in diameter contained large numbers of small and degenerating oocytes. In contrast, follicles more than 3.0 mm in diameter contained a higher percentage of oocytes with good developmental ability.