Treatment of suckling beef cattle with a progestagen sponge and oestradiol benzoate or equine chorionic gonadotrophin.

The research article evaluates how the combination of medroxy-progesterone acetate (MAP) sponges and two different treatments – oestradiol benzoate or equine chorionic gonadotrophin (eCG) – affect the ovarian responses of non-estrus beef cows.

Study Design and Methodology

The experiment involved forty-five suckling Hereford cows that were divided into three equal groups for different treatments:

• The first group received a MAP sponge for seven days along with a 2 mg injection of oestradiol benzoate when the sponge was inserted and another 1 mg when the sponge was withdrawn.
• The second group was administered the same treatment as the first, but additionally received a 400 iu dosage of eCG on the seventh day.
• The third group served as the control and was not subjected to any treatments.

The ovaries of the cows (from all groups) were examined daily using transrectal ultrasonography from day 0 to day 11. Additionally, the cows’ oestrous behaviour was observed from 24 to 96 hours after the withdrawal of the sponge.

Results and Observations

The data obtained from cows that had a corpus luteum present before the withdrawal of the sponges were excluded from the final analysis, leaving only 21 cows across groups 1 and 2, and 11 cows in group 3.

Significant findings from the study include:

• A new follicular wave emerged at an average interval of around 3.9 days following the insertion of the sponge in 19 of the 21 cows in groups 1 and 2. In comparison, this emergence happened after an average of about 3.4 days in all 11 cows in the untreated group.
• Only the six cows with a follicle of 9 mm or larger in diameter were observed to ovulate. This suggests that follicle size could be a critical factor in successful ovulation.
• Out of 11 cows in group 1, which received oestradiol benzoate treatment, 9 came into oestrus. This contrasted with only two out of 10 in group 2, which received eCG, and none in the control group. This indicates that the oestradiol benzoate treatment was significantly more effective at inducing oestrus than the eCG treatment.
• Ovulation was observed in four cows from group 1, two cows from group 2, and none from the control group, further evidencing the impact of the MAP-oestradiol benzoate treatment on ovulation response.

The research provides useful insights into the effects of different hormonal treatments on the ovarian function of beef cattle, which might be useful in managing fertility issues in these animals.