Effect of progestagen intravaginal sponges and PMSG on synchronisation of oestrus in maiden heifers and on interval from calving to oestrus in beef cows

Abstract

The effectiveness of progestagen sponges plus PMSG in inducing and synchronising oestrus and pregnancy in nulliparous heifers was assessed. Eighty-one percent of the treated heifers were synchronised, but none of the controls. The hormone treatment advanced the mean calving date by 19 days, but there was no difference between treated and control in the percentage of heifers that finally calved. The interval between calving and first oestrus for hill-country beef cows 2-10 years old in an untreated control group was 94 days, in a group treated with progestagen-impregnated sponges for 21 days was 98 days, and in a group treated with these sponges plus 1000 i. u. of PMSG at the time of withdrawal was 85 days. The last treatment reduced post-par tum anoestrus by 11 days in comparison with the mean of the other two treatments (P < 0.01). There was no difference between age groups in the percentage of cows showing oestrus, conceiving to first service, and calving for the control treatment. However, in the two hormone treatments none of the 2-year-old cows conceived to first oestrus and 13% calved, but 46% of cows in the older age groups cor1Ceived to first oestrus and 79% calved.

Challenges and opportunities in polymer technology applied to veterinary medicine

“…Polyurethane sponges impregnated with varying amounts of progesterone with different lengths, diameters, and densities have been inserted in cattle (Moore & Smith, ; Davis et al ., ). The sponges exhibited variable retention characteristics depending on different factors such as diameter, length, presence or absence of antibiotic, type of antibiotic applied, animal age, vaginal size, hormone type, rectal palpation, tail characteristics, and sponge density.…”