Effect of follicle age on conception rate in beef heifers

The objective of this study was to determine the effect of age of the ovulatory follicle on fertility in beef heifers. Ovulation was synchronized with the 5 d CO-Synch + controlled intravaginal drug release (CIDR) program in heifers in Montana (MT; n = 162, Hereford and Angus Crossbred) and Ohio (OH; n = 170, Angus Crossbred). All heifers received estradiol benzoate (EB; 1 mg/500 kg BW, [i.m.]) 6 d after the final GnRH of the synchronization program to induce follicular atresia and emergence of a new follicular wave (NFW) followed by prostaglandin F2 alpha (PGF(2 alpha); 25 mg, i.m.) administration either 5 d (young follicle [YF]; n = 158) or 9 d (mature follicle [MF]; n = 174) after EB. Estrous detection was performed for 5 d after PGF(2 alpha) with AI approximately 12 h after onset of estrus. Ovarian ultrasonography (MT location only) was performed in YF and MF at EB, 5 d after EB, PGF(2 alpha), and AI. Heifers in MT (n = 20) and OH (n = 18) that were not presynchronized or did not initiate a NFW were excluded from further analyses, resulting in 142 and 152 heifers in MT and OH, respectively. Heifers from the MF treatment in MT that initiated a second NFW after EB but before PGF(2 alpha) (MF2; n = 14) were excluded from the primary analysis. In the secondary analysis, the MF2 group was compared to MF and YF treatments in MT. Estrous response was similar (90%; 252/280) between treatments and locations. Proestrus interval (from PGF(2 alpha) to estrus) and age of the ovulatory follicle at AI were similar for MF heifers between locations (54.6 +/- 1.7 h and 8.3 +/- 0.07 h) but were greater (P < 0.01) for YF heifers in OH (78.5 +/- 1.4 h and 5.3 +/- 0.06 h) than MT (67.4 +/- 1.6 h and 4.8 +/- 0.06 h; treatment x location, P < 0.01). However, conception rate did not differ for MF (63.8%; 74/116) and YF (67.0%; 91/136) treatments. In the MT heifers, follicle size and follicle age atAI in the YF treatment (10.4 +/- 0.15 mm and 4.8 +/- 0.06 d, respectively) was less (P < 0.01) than in the MF treatment (11.0 +/- 0.18 mm and 8.3 +/- 0.11 d, respectively), but conception rate to AI did not differ between treatments in MT. In the MF2 group proestrus interval was greater (P < 0.01); hence, diameter of the ovulatory follicle and age were similar to that for the YF treatment. Conception rate to AI did not differ between MF2, MF, and YF (61.5, 63.3, and 64.7%, respectively) in MT. In conclusion, manipulation of age of the nonpersistent ovulatory follicle at spontaneous ovulation did not influence conception rate.

Effect of progesterone concentrations, follicle diameter, timing of artificial insemination, and ovulatory stimulus on pregnancy rate to synchronized artificial insemination in postpubertal Nellore heifers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Performance and carcass quality of feedlot- or pasture-finished Nellore heifers according to feeding managements in the postweaning phase

The objective of this study was to evaluate the postweaning history of heifers kept on marandu grass pastures with three canopy heights, in a continuous-grazing system, during the rainy period, on feedlot-or pasture finishing. The effects of three canopy heights (15, 25 and 35 cm) associated with two supplements (mineral salt and protein-energy supplement) and two finishing systems in the dry period (feedlot and open pasture) were studied in the postweaning period during the rainy season. The adopted design was completely randomized, with seven replications (animals) in a 2 x 2 factorial arrangement. The animals which received protein-energy supplement reached the finishing period with greater body weight in relation to those fed mineral salt. In both feedlot and pasture finishing systems, compensatory gain effect was observed in the animals that remained on the low pastures during postweaning compared with the high pastures. This compensatory gain was not verified in the animals that received protein-energy supplement in relation to the mineral salt, and thus the animals were slaughtered beforehand. The heifers on pastures with 25 or 35 cm in height were slaughtered in the same period, and those kept on the low pastures were slaughtered afterwards. The studied factors in the postweaning phase did not affect the carcass characteristics. Animals finished in feedlot slaughtered with the same body weight as those finished on pasture show greater carcass yield, subcutaneous fat deposition and renal pelvic and inguinal fat and greater losses with trimmings for cleaning the main hindquarter meat cuts; however, they provide cuts with the same weight but greater fat cover.

Characterization of the Exonic Regions of the JY-1 Gene in Zebu Cattle and Buffaloes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Growth performance and meat quality of heifers receiving different forms of soybean oil in the rumen

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of manganese supplementation on the membrane integrity and the mitochondrial potential of the sperm of grazing Nelore bulls

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of glycerol on the viability and fertility of cooled bovine semen

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morfometria e compactação da cromatina espermática de touros Nelore de acordo com a idade e sua influência na produção de embriões in vitro

Pós-graduação em Medicina Veterinária - FCAV

Investigation of biofilm production and icaA and icaD genes in Staphylococcus aureus isolated from heifers and cows with mastitis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Non-synonymous mutations mapped to chromosome X associated with andrological and growth traits in beef cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of productivity of sexually precocious Nelore heifers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Metabolism and ruminal parameters of Holstein × Gir heifers fed sugarcane and increasing levels of crude protein

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Association of ADIPOQ, OLR1 and PPARGC1A gene polymorphisms with growth and carcass traits in Nelore cattle

In beef cattle farming, growth and carcass traits are important for genetic breeding programs. Molecular markers can be used to assist selection and increase genetic gain. The ADIPOQ, OLR1 and PPARGC1A genes are involved in lipid synthesis and fat accumulation in adipose tissue. The objective of this study was to identify polymorphisms in these genes and to assess the association with growth and carcass traits in Nelore cattle. A total of 639 animals were genotyped by PCR-RFLP for rs208549452, rs109019599 and rs109163366 in ADIPOQ, OLR1 and PPARGC1A gene, respectively. We analyzed the association of SNPs identified with birth weight, weaning weight, female yearling weight, female hip height, male yearling weight, male hip height, loin eye area, rump fat thickness, and backfat thickness. The OLR1 marker was associated with rump fat thickness and weaning weight (P < 0.05) and the PPARGC1 marker was associated with female yearling weight.