Effect of an equine chorionic gonadotrophin-like recombinant glycoprotein treatment on fertility in Angus cattle.

This study determined the effects of administering a glycoprotein with equine chorionic gonadotropin (eCG)-like activity (eCG-like) on corpus luteum (CL) area, serum progesterone concentrations, incidence of multiple ovulations (MOV), estrus expression rate (EER), and pregnancy to timed AI (P/TAI) in Angus cattle synchronized with a 5-d Co-Synch protocol. On Day -8, cattle were body condition scored (BCS), and received a 1.0 g progesterone intravaginal device (IVD) and 100 µg GnRH. On Day -3, the IVDs were removed and 500 µg cloprostenol was administered intramuscularly (i.m.). Cattle were randomly assigned into one of two groups: eCG-like (heifers, n = 232, primiparous, n = 148, and multiparous cows = 485; 300 IU (heifers) and 400 IU (cows) eCG-like i.m. on Day -3), or Control (heifers, n = 240, primiparous, n = 151, and multiparous cows, n = 478; no eCG-like). On Day -2, cattle received a second dose of 500 µg cloprostenol, and on Day 0, 100 µg GnRH was given concurrently with TAI. Estrus expression rate was assessed by observing the tail paint rubbed off in a subset of heifers (n = 372) and all cows on Day 0. Transrectal ultrasonography was used to evaluate the presence of CL on Day -8 and to diagnose P/TAI on Day 30-35. In a subset of cattle (heifers = 194 and multiparous cows = 87), CL area, serum progesterone concentrations, and incidence of MOV were evaluated on Day 7. Heifers, primiparous, and multiparous cows were analyzed separately. Treatment with eCG-like did not affect (P > 0.1) EER in heifers. Estrus expression rate was increased (P ≤ 0.03) in primiparous (68.9 % vs 45.0 %) and multiparous (75.5 % vs. 68.8 %) cows treated with eCG-like compared with Controls. Pregnancy/TAI was increased (P < 0.01) in heifers (65.2 % vs 48.3 %) and primiparous cows (48.3 % vs. 35.1 %) treated with eCG-like than Controls. In multiparous cows with a BCS ≤4 P/TAI was increased (P = 0.03) in the eCG-like group (47.7 %) than the Control group (34.8 %) but was similar (P > 0.1) between treatment groups in multiparous cows with a BCS ≥4.5. The eCG-like treatment increased (P < 0.05) CL area in heifers and multiparous cows and tended (P = 0.10) to elevate serum progesterone concentrations only in heifers. However, it did not affect (P > 0.1) the incidence of MOV in heifers and multiparous cows. Glycoprotein eCG-like administration increased fertility in heifers and primiparous cows, but in multiparous the effect of eCG-like on fertility was associated with BCS.

Comparison of the 7-day CO-Synch and 8-day estradiol-based protocols for estrus synchronization and timed artificial insemination in suckled Bos taurus cows.

Two experiments were conducted to compare, follicle diameter (FD) on Day -1, corpus luteum (CL) area on Day 7, progesterone (P4) concentration on Day 7 and 18, pregnancy per timed artificial insemination (TAI) on Day 30, and pregnancy loss (PL) between Days 30 and 60 after TAI (TAI, Day 0) using two different synchronization protocols. In Experiment 1, Angus cows (n = 1148) were randomly assigned to either 7-d progesterone CO-Synch (7-d CO-Synch) or 8-d progesterone + estradiol (8-d P + ES) synchronization protocols for TAI. On Day -10, cows in the 7-d CO-Synch treatment group (n = 574) received a progesterone-releasing intravaginal device (PIVD; 0.5 g P4) and GnRH (0.105 mg), on Day -3 the PIVD was removed and cows received cloprostenol (0.150 mg), then, on Day 0 (64 h after PIVD removal), cows received GnRH (0.105 mg) and were TAI. On Day -10, cows in the 8-d P + ES treatment group (n = 574) received a PIVD (0.5 g P4) and estradiol benzoate (2.0 mg), on Day -2 the PIVD was removed, and cows received cloprostenol (0.150 mg) and estradiol cypionate (0.5 mg), then, on Day 0 (48 h after PIVD removal), cows were TAI. Pregnancy per TAI was determined on Days 30 and 60. In a subset of cows (7-d CO-Synch, n = 41; 8-d P + ES, n = 40), serum P4 concentration was evaluated on Day 18. In Experiment 2, anestrus (n = 34) and cyclic (n = 34) suckled beef cows were selected and submitted at random on Day -10, to either 7-d CO-Synch or 8-d P + ES treatment groups. Follicle diameter on Day -1, CL area, and serum P4 concentration on Day 7 were determined. In Experiment 1, pregnancy per TAI on Day 30 did not differ (7-d CO-Synch = 48.9%; 8-d P + ES = 45.6%) between treatments but it was greater for cows with BCS ≥5 (P < 0.01). Pregnancy loss between Days 30 and 60 did not differ between treatment groups but tended to be greater in cows with BCS <5.0 (P < 0.1). In a subset of cows, serum P4 concentration on Day 18 did not differ between treatment groups but tended to be lower (P < 0.1) in cows that had PL between Days 30 and 60 compared to cows that had no PL. In Experiment 2, FD tended to be greater (P < 0.1) and CL area was greater (P = 0.05) in anestrus cows from 7-d CO-Synch treatment. In cyclic cows, the treatment did not affect the FD or CL area. In conclusion, there was no difference in pregnancy per TAI on Day 30 and PL between Days 30 and 60 between cows using 7-d CO-Synch + PIVD or 8-d estradiol-based + PIVD protocols for estrus synchronization and TAI.

Age at First Gestation in Beef Heifers Affects Fetal and Postnatal Growth, Glucose Metabolism and IGF1 Concentration.

This study aimed to determine the effects of age at first gestation on offspring growth performance, glucose metabolism, and IGF1 concentration. Heifers impregnated by AI from a single bull at 15 months of age (15 M, n = 20), or 27 months of age (27 M, n = 20), and multiparous cows (adult, n = 20) were used. Dams from all groups were managed in a single group during gestation and lactation. Gestational length was longer in the 15 M and 27 M than in adult dams (p = 0.009). Bodyweight at birth, at weaning and ADG during lactation were higher in calves from adult dams than in those from 27 M dams, and higher in calves from the latter than in 15 M calves (p < 0.001). Calves from 15 M dams had an increased head circumference/BW ratio compared to calves from 27 M dams, while calves from this latter group had an increased ratio compared to calves from adults (p = 0.005). Body mass index was greater in calves from adults than in those from 15 M and 27 M dams (p = 0.002). Milk production from 15 M and 27 M dams was similar but lower than that from adults (p = 0.03). Calves born from adult dams had greater blood glucose concentrations than those from 15 M and 27 M dams (p < 0.05). Serum IGF1 concentrations were higher in calves from adults than in calves from 15 M and 27 M dams (p = 0.01). This study showed that age at first gestation affects offspring postnatal growth performance, glucose metabolism and IGF1 concentration.

Maternal energy status during late gestation: Effects on growth performance, carcass characteristics and meat quality of steers progeny.

The objetive of the current study was to determine the effect of maternal energy status during late gestation on growth performance, carcass characteristics and meat quality of steer progeny. At 180 ±â€¯4 d of gestation 56 multiparous Angus cows were blocked by BW and expected calving date and asigned to three levels of nutrition energy: SR (severe restricted; 50% of NRC requirement), MR (moderate restricted; 75% of requirement) and NR (no restricted; 100% of requirement). After parturition, all cows were managed in a single group during lactation. A total of 25 male calves (SR = 8 calves; MR = 9 calves; NR = 8 calves) were born from pregnant cows and all pens had at least one male calf. After weaning, male calves were separated of female calves and were stockered on native range until 24 ±â€¯0.1 months of age then placed into a feedlot for 104 d before harvest. Cow BW and BCS decreased linearly (P < .01) as nutritional energy restriction increased. Calves from SR dams were lighter (P = .04) than calves from MR and NR dams at parturition, however, at weaning and harvest BW was similar for SR and NR steers and decreased in MR steers. Steers from SR dams demonstrated catch-up growth with a tendecy to increased ADG from birth to harvest compared to MR and NR steers (P = .06). Hot carcass weigth was similar in SR and NR steers and increased in MR steers (P = .01). Longissimus muscle area was not affected (P > .10) by maternal energy status, however, 12 rib fat thickness was greater in SR and MR compared to NR steers (P < .01). Tenderness of Longissimus muscle was decreased in MR compared to SR and NR steers after 3d of aging. No treatment differences (P > .10) were observed in sarchomere length or collagen content. Adipocyte diameter was similar (P > .10) between treatments suggesting that decreased 12th rib fat thicness in MR steers could be due to decreased fat tissue hyperplasia. These results indicate that level of energy restriction during late gestation does no have linear response on growth performance and carcass quality of steers progeny.

The influence of protein restriction during mid- to late gestation on beef offspring growth, carcass characteristic and meat quality.

The objective of this study was to determine whether crude protein intake during the last three months of gestation affects growth performance, carcass characteristics and meat quality of steer progeny. At 134 ±â€¯14 d of gestation, 68 multiparous Angus cows were blocked by BW and expected calving date and randomly assigned to diets that contained either low or high dietary crude protein concentrations and were allotted in 12 pens per treatment. After calving, cows were managed together on improved pastures during lactation. After weaning at 219 ±â€¯13 d of age, steers calves were stockered on natural pastures until 687 ±â€¯13 d of age then placed into a feedlot for 83d before slaughter. Maternal dietary protein concentration had no influence on offspring body weight and growth rate during rearing or finishing phases (P > .10). Rib fat thickness of steers was not affected (P = .38) by maternal nutrition treatments, however, LM area was greater in HP steers than LP steers at entrance into the feedlot (P = .01) and end of finishing phase (P = .04). Hot carcass weight was similar between treatments (P = .69), however dressing percentage was increased in HP relative to LP steers (P = .01). Tenderness of Longissimus muscle was increased in HP compared to LP steers after 3 and 14d (P < .001) of aging. No treatment differences in troponin-t degradation (P = .77) and collagen content (P = .58) were observed. Muscle fiber diameter was similar in LP and HP steers (P = .20), suggesting that increase of LM area in HP steers could be due to muscle hyperplasia. These data indicated that level of protein during mid to late gestation does not affect offspring growth but has impacts on carcass composition and meat quality of steer progeny.

Enzootic calcinosis in horses grazing Solanum glaucophyllum in Argentina.

Solanum glaucophyllum, a toxic plant known for its calcinogenic effects, causes enzootic calcinosis in ruminant and monogastric animals. We describe an outbreak of enzootic calcinosis that occurred in a herd of 110 horses grazing pastureland heavily contaminated with S. glaucophyllum in Buenos Aires province, Argentina. Ten horses developed clinical signs, and 6 horses died. Clinical signs included abnormal gait (stiff-legged action, short strides), stiffness, thoracolumbar kyphosis, reluctance to move, wide stance, chronic weight loss, weakness, recumbency, and difficulty standing. Autopsy of 2 horses revealed severe mineralization of the aorta, pulmonary arteries, heart, and lungs, consistent with enzootic calcinosis. Although horses usually have very selective grazing behavior, under food restriction conditions, they can ingest the toxic plants and can develop the disease. Enzootic calcinosis should be considered as a differential diagnosis in horses grazing S. glaucophyllum-invaded pasturelands with compatible clinical signs and lesions.