Elsevier

Theriogenology

Volume 82, Issue 3, August 2014, Pages 481-489
Theriogenology

Research article
Use of a single injection of long-acting recombinant bovine FSH to superovulate Holstein heifers: A preliminary study

https://doi.org/10.1016/j.theriogenology.2014.05.011Get rights and content

Abstract

Our objective was to compare several experimental preparations of a single injection of long-acting recombinant bovine FSH (rbFSH; types A and B) to a porcine pituitary-derived FSH (Folltropin) to superovulate Holstein dairy heifers. Nonlactating, nonpregnant virgin Holstein heifers (n = 56) aged 12 to 15 months were randomly assigned to one of four superstimulatory treatments. Beginning at a random stage of the estrous cycle, all follicles greater than 5 mm were aspirated. Thirty-six hours later, heifers received an intravaginal P4 device and superstimulatory treatments were initiated. Treatments were (1) 300 mg of pituitary-derived FSH (Folltropin) administered in eight decreasing doses over a period of 3.5 days; (2) a single injection of 50 μg of A-rbFSH; (3) a single injection of 100 μg of A-rbFSH; and (4) a single injection of 50 μg of B-rbFSH. All heifers received 25 mg PGF at 48 and 72 hours after the insertion of P4 device. At 84 hours after insertion, P4 devices were removed, and ovulation was induced 24 hours later with hCG (2500 IU). Heifers were inseminated at 12 and 24 hours after hCG treatment. The number of ovulatory follicles was greatest for heifers treated with Folltropin and B50-rbFSH, least for heifers treated with A50-rbFSH, and was intermediate for heifers treated with A100-rbFSH (25.7 ± 3.2, 18.9 ± 3.2, 5.9 ± 0.9, and 16.6 ± 3.1, respectively; P < 0.001). The number of corpora lutea was greatest for heifers treated with Folltropin, B50-rbFSH, and A100-rbFSH, and least for heifers treated with A50-rbFSH (19.1 ± 2.4, 16.1 ± 3.0, 15.9 ± 2.9, and 2.6 ± 0.9, respectively; P < 0.001). The number of good-quality embryos differed among treatments and was greatest for heifers treated with B50-rbFSH, Folltropin, and A100-rbFSH and least for heifers treated with A50-rbFSH (7.6 ± 2.4, 6.5 ± 1.7, 4.3 ± 1.5, and 0.8 ± 0.5, respectively; P < 0.001). In conclusion, a single injection of a preparation of long-acting rbFSH (either 100 μg of A-rbFSH or 50 μg of B-rbFSH but not 50 μg of A-rbFSH) produced similar superovulatory responses resulting in the production of good-quality embryos when compared with a pituitary-derived FSH preparation administered twice daily for 4 days. More studies using different types of cattle and different doses of rbFSH are needed to confirm the findings reported in this preliminary study.

Introduction

Multiple ovulation and embryo transfer (MOET) is a reproductive biotechnology used worldwide and allows for increased production of offspring from genetically superior dams. Pituitary-derived porcine FSH has been used to superovulate cattle during the past few decades and is commercially available for use in cattle; however, because of its relative short half-life of approximately 5 hours in cows [1], [2], pituitary-derived porcine FSH requires frequent administration (twice daily over a period of 4 days) to maintain adequate circulating levels of FSH to induce a successful superstimulatory response.

Since the early stages of MOET, researchers and practitioners have sought protocols requiring less handling of donor animals without compromising the yield of high-quality embryos. The development of hormonal synchronization protocols that allow for timed artificial insemination (AI) have had a considerable impact on the overall results of MOET programs and have facilitated donor management [3]. In addition, strategies allowing for successful superovulation with reduced frequency of treatments can decrease the handling of donors by up to 75%, thereby reducing costs per embryo produced [4]. Several approaches have been pursued to decrease the number of FSH treatments required to superovulate donors with interesting but varying results including once daily subcutaneous (sc) FSH injections [5]; once daily sc injections of FSH dissolved in saline and a gelatin gel [6]; a single sc FSH injection [7], [8]; a single intramuscular (im) injection of FSH dissolved in polyvinylpyrrolidone [9]; a single [10] or slip-single [11] im injection of FSH dissolved in hyaluronan; or a single im injection of FSH dissolved in hydroxide gel [12]. All these studies used pituitary-derived FSH preparations, and superovulation studies using a single treatment of recombinant bovine FSH (rbFSH) have not been reported.

Preparations of pituitary-derived FSH might present batch-to-batch variations in the biologic activity and, or purity of the hormone, and the use of a recombinant FSH preparation might reduce the variation observed in the pituitary-derived FSH [4], [13]. Several studies have used rbFSH to induce superstimulation of follicles in heifers and mature cows [14], [15], [16] with interesting results. Those studies did not use a long-acting rbFSH (LArbFSH) preparation, and multiple treatment with FSH over a period of 3 to 6 days was required to induce a superstimulatory response. In addition, repeated use of exogenous FSH from one species (e.g., swine) to induce superstimulation of donors in a different species (e.g., rabbits) might induce a humoral immune response, thereby reducing the superstimulatory response after repeated exposure of the donor, at least in goats [17], rabbits [18], and marsupials [19]. Equine chorionic gonadotropin (eCG) has been used to superstimulate cattle, and the use of repeated treatments with high doses of eCG induced a humoral immune response (reviewed by Baruselli et al. [20]). Exogenous recombinant FSH from the same species (e.g., ovine recombinant FSH used in ewes) may prevent this humoral immune response and transmission of diseases across species.

The objective of this experiment was to compare the efficacy of a single injection of two types (A and B) of LArbFSH using experimental doses to a standard pituitary-derived FSH preparation administered twice daily to superovulate Holstein heifers. Our hypothesis was that superstimulatory and superovulatory responses and the number of good-quality embryos produced would be similar between heifers treated with a single injection of LArbFSH compared with heifers treated twice daily with a standard pituitary-derived FSH preparation.

Section snippets

Animals, feeding and housing

Nonlactating, nonpregnant virgin Holstein heifers aged 12 to 15 months from two commercial dairy herds (n = 56, farm A = 40 and farm B = 16) located in South-central Wisconsin were used. The experiment was conducted during July 2012. Heifers were housed in open lot corrals equipped with self-locking head gates at the feedline, and heifers had free access to feed and fresh water ad libitum throughout the experiment. Heifers were fed once daily a total mixed ration diet (similar at both

Superstimulatory and superovulatory outcomes

The number of ovulatory follicles at the time of hCG treatment, number of CL at the time of embryo collection, proportion of heifers considered to have responded to the superstimulatory treatments, and ovulation rate are summarized in Table 1. The number of ovulatory follicles was greater for heifers treated with Folltropin than for heifers treated with A100-LArbFSH (P = 0.03) or A50-LArbFSH (P < 0.001). Interestingly, the number of ovulatory follicles did not differ between heifers treated

Discussion

This preliminary study evaluated the efficacy of a single injection of LArbFSH to superstimulate growth of ovarian follicles in Holstein heifers. Our hypothesis was that superstimulatory and superovulatory responses and the number of good-quality embryos recovered would be similar for heifers treated with a single injection of LArbFSH compared with heifers treated with a standard pituitary-derived FSH. Our results partially supported this hypotheses based on the following observations: (1)

Acknowledgments

The authors thank the Cottonwood Dairy and Wagner Dairy for use of their heifers to conduct this study and Peter Crump for statistical consultation. We also thank CEVA Animal Health for donating the LArbFSH. This study was supported by CEVA Animal Health, Hatch project WIS01171to P.M.F., and a fellowship from the Universidad Francisco de Paula Santander of Colombia to G.M. Baez (COLCIENCIAS-497).

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