Association between A59V polymorphism in exon 3 of leptin gene and reproduction traits in cows of Iranian Holstein

We used the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique to screen for DNA polymorphisms of the leptin gene in 255 cows of Iranian Holstein. Amplified region is located in exon 3 of leptin gene. The genomic bovine leptin sequences, which consist of three exons, were obtained from GeneBank (Accession number U50365). Genotype frequencies in all herds were 0.588, 0.388 and 0.024 for AA, AB and BB, respectively, and allelic frequencies were 0.782 and 0.218 for A and B, respectively. We investigated effect of A59V polymorphism in the leptin gene on three reproduction traits. Significances of the genotype effects were tested using approximated F-statistic provided by SAS (v.8, GLM procedure). This study showed that genotype had no effect on open days and calving interval (NS) but had significant effect on length of pregnancy (P < 0.01). Animals with the AA genotype had higher length of pregnancy than other genotypes.Keywords: Leptin, Iranina Holstein, polymerase chain reaction-restriction fragment length polymorphism, reproduction traitAfrican Journal of Biotechnology Vol. 9(36), pp. 5997-6000, 6 September, 201

Quantification of the uterine involution and dimensions, hormonal response and reproductive performance of pyometric and healthy dairy cows treated with Dinoprost

The aim of the present study was to investigate the effects of a PGF2α analogue (Dinoprost) on involution of the puerperal uterus, especially with pyometra during 35 to 45 days postpartum in multiparous high yielding Holstein dairy cows. At days 40 ± 5 postpartum, 1250 cows were ultrasonographically examined. Fifty cows were diagnosed as pyometric. Fifty pyometric and 50 clinically healthy cows were assigned randomly to one of four groups. Groups were: 1.) Pyometric+Dinoprost cows (PD, n = 25 treated with 25 mg of Dinoprost), 2.) Pyometric+Saline cows (PS, n = 25 treated with saline), 3.) Healthy+Dinoprost cows (HD, n = 25 treated with 25 mg of Dinoprost), and 4.) Healthy+Saline cows (HS, n = 25 treated with saline). All treatments were given intramuscularly. Ultrasonography was performed at the time of examination and 7 days later to evaluate changes in uterine diameter. Treatment with Dinoprost significantly reduced gross uterine diameter in PD in comparison to the PS group in the presence or absence (P4 concentrations <1 ng/ml) of an active corpus luteum. Dinoprost treatment did not decrease gross uterine diameter in groups HD and HS. Luminal diameter was significantly smaller in the PD than in the PS group. Pregnancy rate of PD was greater than PS cows (36% vs 20%, respectively). Days to first service (110 d vs. 140 d) and open days (160 d vs. 190 d) were shorter in PD cows than PS cows. It was concluded that injection of 25 mg of Dinoprost to pyometric cows had uterotonic effects in presence or absence of functional corpus luteum. Therefore, this treatment can help uterine involution in puerperal dairy cows affected by pyometra and consequently improved reproductive performance.Keywords: Cattle, Dinoprost, pregnancy rate, pyometra, uterine healt

Effect of oral administration of pioglitazone on follicular dynamics in Holstein dairy cows

This study investigated the effects of oral administration of pioglitazone (PGT), a specific and synthetic ligand of peroxisome proliferator-activated receptors gamma (PPARγ), on follicular dynamics and corpus luteum (CL) functionality in dairy cows. Cows exhibiting strong signs of estrus after 2 injections of PGF2α (given14 d apart) at d 30 postpartum (n = 28) were allotted to four groups (n = 7 cows/treatment) and orally received 6 mg PGT/kg body weight/day according to the following protocol: no PGT (control); PGT for 14 d from 7 d before expected estrus (10 d after 1st injection of PGF2α) to 7 d after observed estrus (PGT14); PGT for 21 d after observed estrus (PGT21); and PGT for 28 d, 7 d before expected estrus to 21 d after observed estrus (PGT28). During the first follicular wave, number of follicles (total and small) increased in PGT14 and PGT28 cows compared to the control group (P < 0.05). During the ovulatory wave, number of total and small follicles increased in PGT28 (P < 0.05) and PGT21 (P < 0.10) compared with PGT14 and control cows. Size of the largest follicle at first wave was greater in PGT28 (P < 0.05), PGT14 (P < 0.05) and PGT21 (P < 0.10) compared to the control cows. Maximal size of the ovulatory follicle was greater in PGT28 (P < 0.05) and PGT21 (P < 0.10) groups compared to the control group. Growth rate of the largest follicle at first wave was higher (P < 0.05) in PGT-treated cows, while growth rate of the ovulatory wave was higher in PGT28 and PGT21 groups, leading to shorter days from luteolysis to ovulation. Pioglitazone administration did not affect CL size, but increased progesterone (P4) concentration. The PGT14 and PGT28 cows had higher maximal plasma P4 concentration and shorter intervals to reach maximal plasma P4 compared to the control group. In conclusion, oral administration of PGT had some positive effects on follicular development and circulating P4 levels which may be conducive to better reproductive performance

GnRH injection before artificial insemination (AI) alters follicle dynamics in Iranian Holstein cows

The objective of the present study was to evaluate the ovarian response of cows to gonadotropinreleasing hormone (GnRH) injection on day 6 of the estrous cycle. The estrous cycles of 10 cows were synchronized with 2 intramuscular (im) injections of prostaglandin F2   given 11 d apart. The cows were randomly assigned to 1 of 2 treatments. Cows in the control treatment received no treatment, whereas GnRH6 cows received a GnRH injection on d 6 of the estrous cycle (estrus = d 0). Daily, from estrus d 0 to the next estrus d 23, cows had their ovaries scanned by ultrasound. Profiles of the mean number of follicles (that is, 4 - 6 mm and 7 mm) and the diameter of the largest follicle (F1) were compared by least squares analysis of variance using the general linear model (GLM) procedure of SAS. In response to an injection of GnRH, the number of small follicles in group GnRH6 on day 6 (1.5 ± 0.6 follicles) increased (P 0.05) on day 8 (5.0 ± 0.7 follicles) and the number of medium and large follicles ( 7 mm) on day 6 (2.0 ± 0.5 follicle) decreased (P 0.05) on day 9 (0.8 ± 0.6 follicles). In conclusion, an injection of GnRH on day 6 of the estrous cycle could promote the emergence of a new follicular wave in cows