Sk Srivastava

Fertility responses and hormonal profiles in repeat breeding cows treated with insulin

The influence of insulin treatment on conception rate and endocrine profile was studied on 21 repeat breeding cows divided randomly into two groups, i.e. insulin treatment (n = 11) and control (n = 10). Cows of the insulin treatment group were injected subcutaneously with a long acting purified form of bovine insulin at 0.2 IU/kg body weight/day on days 8, 9 and 10, and then with 0.75 mg tiaprost (PGF(2)alpha) intramuscularly on day 12 of the oestrous cycle (oestrus = day 0). The cows of the control group only received 0.75 mg tiaprost was injected intramuscularly on day 12. There was no difference (P > 0.05) in the interval to the onset of oestrus and subsequent cycle length between the treatment (84.5 +/- 6.6 h and 21.2 +/- 0.6 days, respectively) and the control (72.3 +/- 5.9 h and 19.7 +/- 0.4 days, respectively) groups. First service conception rate and overall pregnancy rate did not differ (P > 0.05) between the insulin treatment group (45.4 and 63.6%) and the control group (33.3 and 40.0%). Progesterone concentration following administration of insulin increased (P < 0.05) in the insulin treated cows (2.2+/-0.4 ng/ml versus 2.9 +/- 0.4 ng/ml) but the concentration of oestradiol-17beta did not differ. The insulin concentration was higher on day 10 of the oestrous cycle (P < 0.05) in the treatment group (71.0 +/- 12.5 microU/ml versus 38.1 +/- 4.5 microU/ml). The insulin and glucose concentrations were higher (P > 0.05) in animals, which subsequently became pregnant than in non-pregnant animals. The results may indicate that there is beneficial effect of insulin on fertility in repeat breeder cattle.

Sequestration of PDC-109 protein improves freezability of crossbred bull spermatozoa

A study was carried out to assess the effect of sequestration of PDC-109 protein, a majority constituent of heparin binding proteins (HBP) of seminal plasma, on freezability and in vitro fertilizing ability of crossbred bull spermatozoa after cryopreservation. The study consisted of isolation and characterization of PDC-109 protein to raise anti-sera against it in rabbits. Following which, raised antibodies against PDC-109 protein was quantitated and coated in tubes used for collection of ejaculates. Semen ejaculates thus collected were cryopreserved using EYTG extender. Physico-morphological characteristics, viz. motility, viability, acrosomal integrity and HOS response as an indicator of freezability of cryopreserved spermatozoa were determined at pre freeze as well as post thaw stage. At pre freeze stage, a significant (p<0.05) improvement in viability (83.83 ± 2.18 vs 75.17 ± 2.42) and acrosome integrity (81.33 ± 2.38 vs 72.83 ± 2.39) in antibodies treated group than control was observed. Similarly, increase in HOS responsive spermatozoa was highly significant (p<0.01) than control (78.83 ± 1.69 vs 67.5 ± 1.75). At post thaw stage, significant (p<0.05) improvement in viability (69.50 ± 2.16 vs 60.33 ± 2.19) and HOS responsive spermatozoa (68.67 ± 1.62 vs 58.50 ± 1.32) and highly significant (p<0.01) increase in individual motility (56.17 ± 1.83 vs 47.00 ± 1.86) and acrosome integrity (75.17 ± 2.38 vs 61.83 ± 2.1) was observed in antibodies treated group when compared to control was observed. The results from the study revealed that sequestration of PDC-109 protein from semen samples leads to significant improvement in pre-freeze and post-thaw values of above parameters in cryopreserved spermatozoa. It is thus concluded that sequestration of PDC-109 protein from ejaculates improves freezability of crossbred bull spermatozoa.

Bovine seminal PDC-109 protein: An overview of biochemical and functional properties

Although long-term storage of bovine semen is desirable for wider use, successful cryopreservation depends on several factors, including various proteins present in seminal plasma. One such group of proteins, viz. bovine seminal plasma (BSP) proteins represents the major protein fraction in bovine seminal plasma. They constitute three major heparin-binding (HB-) acidic proteins secreted by seminal vesicles, viz. BSP-A1/-A2 (PDC-109), BSP-A3 and BSP-30-kDa. By purification studies it was deduced that PDC-109 is a polypeptide of 109 amino acids and contains two tandem repeating fibronectin type-II (Fn-II) domains, preceded by a 23 residue N-terminal domain. Though BSP-A1 and BSP-A2 are biochemically similar they differ only in glycosylation and their mixture is called PDC-109 or gonadostatins. PDC-109 exists as a polydisperse, multimeric self-associated molecule and possesses multifunctional properties, viz. binding to the surface of plasma membrane of spermatozoa causing conformational change in the sperm surface proteins and enhances motility. Besides binding, PDC-109 protein provokes cholesterol efflux from sperm membrane and promotes sperm reservoir by interacting with oviductal membrane. Interaction of sperm with PDC-109 protein induces sperm capacitation and acrosome reaction. However, prolonged exposure of spermatozoa with free floating PDC-109 protein as during processing for preservation, increases cholesterol efflux from spermatozoa. The efflux of sperm membrane cholesterol and disturbance in cholesterol:phospholipids ratio causes destabilization of plasma membrane thereby inducing cryoinjury to the sperm. In this review, the biochemical, functional properties of PDC-109 protein and its role during semen cryopreservation is summarized.

Cryoinjury in relation to cholesterol content of bull spermatozoa

Though semen cryopreservation has many advantages, it decreases tolerance of spermatozoa to stress of temperature variations, thus disposing spermatozoa to increased cryoinjury. Predicting cryoinjury to spermatozoa is difficult with available laboratory protocols. The present study was designed to evaluate the cryoinjury prediction of sperm in relation to its cholesterol content. The cholesterol content at fresh, pre-freeze and post-thaw stage was 21.95±0.97, 9.58±0.45 and 7.44±0.44 ig/100 million spermatozoa. Semen quality parameters (SQP) at pre-freeze and post-thaw stages were individual motility (71.58±1.29 vs. 47.83±1.16), acrosome integrity (71.00±1.48 vs. 61.58±1.70), Chlortetracycline (CTC) pattern (F: 29.67±1.14 vs. 15.83±1.02; B: 48.83±2.06 vs. 53.58±1.27; AR: 21.50±1.84 vs. 30.58±1.85). Study indicated that cholesterol content of fresh spermatozoa could be used to predict cholesterol content of spermatozoa at pre-freeze and post-thaw stages with medium to high level of accuracy. This study revealed strong evidence that cholesterol content of pre-freeze bull spermatozoa could be a good predictor of level of cryoinjury following preservation at ultra low temperature.