The effects of progesterone treatment following artificial insemination on the reproductive performance of dairy cows

Abstract

The objective of this study was to examine the effects of increasing circulating progesterone in multiparous Holstein cows, using an intravaginal progesterone implant between days 3 and 7 following fixed-time artificial insemination (FTAI). The animals were randomly assigned into two groups: (1) treatment group and (2) control (no treatment). The experiment took place during periods of high and mild temperatures. Pregnancy rates were evaluated by ultrasound at 30 and 60 days after FTAI; embryonic and fetal mortality rates were also evaluated on these dates. The temperature and humidity index on the day of FTAI were different (P < 0.05) during the times of interest, but it did not affect conception rates. Neither the conception rates at days 30 and 60 nor the embryonic and fetal mortality rates differed between the groups during either the high- or mild-temperature periods (P > 0.05). Throughout the experimental period, the serum progesterone concentration was higher in the treatment group than in the control (P < 0.05). We conclude that the intravaginal progesterone implant inserted from days 3 to 7 following FTAI had no effect on conception rates at days 30 and 60 or on embryonic or fetal mortality rates but enhances the serum progesterone concentrations following treatment in multiparous Holstein cows during high- and mild-temperature periods.

Effect of shading in physiological responses, milk yield and quality of Girolando cows

“…The temperature and humidity of the milking parlor were recorded daily at the time of the two milking with the temperature expressed in °C, and humidity in percentage. During the experimental period, the daily temperature and humidity index (THI) was calculated according to the model previously used (Marques et al, 2014), with THI = 0.8 x T + [(RH (%) / 100) x (T -14.4)] + 46.4, where T is the temperature in °C and RH is the relative air humidity, measured by a digital thermo-hygrometer (Instrutemp, Belenzinho, São Paulo, Brazil).…”

Influências da condição corporal e atividade ovariana sobre a taxa de prenhez de vacas de corte suplementadas com progesterona de longa ação após a IATF

“…Os resultados reportados sobre o efeito da suplementação de P4 no início do diestro são divergentes, variando de resultados positivos (JOHNSON et al, 1958;ROBINSON et al, 1989), resultados neutros (VAN CLEEFF et al, 1991;STEVENSON et al, 1991;ARNDT et al, 2009;GARCIA-ISPIERTO et al, 2012;COLAZO et al, 2013;MONTEIRO et al, 2014;MARQUES et al, 2014) e também resultados negativos (VAN CLEEFF et al, 1996;PARR et al, 2014). No entanto, estes estudos apresentaram muitas diferenças entre categoria animal (primíparas vs pluríparas), métodos para aumentar a concentração de P4, início da suplementação de P4 relativo ao dia da IA e número de animais utilizados nos trabalhos.…”

“…No entanto, estes estudos apresentaram muitas diferenças entre categoria animal (primíparas vs pluríparas), métodos para aumentar a concentração de P4, início da suplementação de P4 relativo ao dia da IA e número de animais utilizados nos trabalhos. Diversos estudos avaliando a suplementação com P4 por meio de dispositivos intravaginais de P4 em vacas de leite também não indicaram aumento na P/AI (VAN CLEEFF et al, 1991;STEVENSON et al, 1991;ARNDT et al, 2009;GARCIA-ISPIERTO et al, 2012;COLAZO et al, 2013;MARQUES et al, 2014). Monteiro (2014) JOHNSON et al, 1958;ROBINSON et al, 1989).…”