Impact of luteal blood perfusion and expression of estrus on pregnancy rates of Bos taurus embryo recipients exposed to fixed-time embryo transfer.

This study evaluated the impact of luteal blood perfusion (BP) and expression of estrus on pregnancy rates of Bos taurus embryo recipients exposed to fixed-timed embryo transfer (FTET) using a gonadotropin-releasing hormone (GnRH)- and progesterone-based ovulation synchronization protocol. Postpartum beef cows (n = 746) were exposed to a GnRH/progesterone-based ovulation synchronization protocol. Luteal morphometry and BP were assessed using color Doppler ultrasonography 9 days after CIDR removal concurrently with FTET.

Influence of early progesterone removal on follicular development, expression of estrus, and pregnancy rates in presynchronized postpartum beef cows.

The objective of this study was to evaluate the impact of early progesterone removal on pregnancy rates to fixed-time artificial insemination (FTAI) in presynchronized beef cows. Postpartum beef cows (n = 882) were randomly assigned to 1 of 2 treatments: 1) 7&7 Synch: cows received a controlled internal drug release insert (CIDR) and a 25-mg injection of prostaglandin F on day 0, 100 μg of GnRH on day 7, a second injection of prostaglandin F (PG2) at CIDR removal on day 14, and a second injection of GnRH at FTAI 60-66 h after PG2 (day 17); 2) 7&6 Synch: cows received the same treatment as 7&7 Synch; however, CIDR removal occurred in conjunction with PG2 on day 13, while FTAI remained at 60-66 h after CIDR removal (day 16). Ovarian ultrasonography was performed to determine follicle diameter at PG2 and FTAI in a subset of cows (n = 40).

A proposed model to evaluate how changes in body condition score and the fatty acid profile of a supplement affect physiology and metabolic responses of nonlactating females.

Two experiments were designed to evaluate the effects of altering body condition score (BCS) and the profile of a fatty acid (FA) supplement on the metabolism of Nellore females. In experiment 1, 16 and 24 heifers and nonlactating cows, respectively, were assigned to (1) maintenance diet (MNT-MNT; n = 10), (2) maintenance diet and BCS loss (MNT-LSS; n = 10), (3) maintenance diet supplemented with calcium salts of soybean oil for 30 d and BCS loss for 40 d (MNT+CFA-LSS; n = 10), and (4) maintenance diet for 30 d and BCS loss for 40 d with a diet containing calcium salts of soybean oil (MNT-LSS+CFA; n = 10). Following the BCS loss period, MNT-LSS, MNT+CFA-LSS, and MNT-LSS+CFA were fed a diet to promote the gain of BCS.

Effects of supplementing narasin to heifers during late-gestation and lactation on development of the offspring.

This experiment evaluated the effects of supplementing narasin during late-gestation and lactation on productive and physiological responses of beef heifers and their offspring. Pregnant, nulliparous Nelore heifers ( = 88) that conceived under the same fixed-time artificial insemination protocol and to the same sire were used. Heifers were ranked by maternal ability genomic score, body weight () and body condition score () and allocated to 44 drylot pens (2 heifers per pen; 10 × 25 m).