Группа авторов

Bovine Reproduction


Скачать книгу

Heifers for Attainment of Puberty

      The rearing of replacement heifers is a major financial investment for both beef and dairy cattle producers. The investment expenses do not begin to be recovered until after the first calf is weaned and sold, or in the case of dairy heifers, the onset of lactation, so having heifers calve at an optimal age is paramount to enterprise profitability. For this to occur it is essential that operators know when their heifers have attained puberty and become eligible for breeding. This is most critical for herds using a restricted breeding season.

      Observation of signs of estrus can predict onset of puberty but is impractical for application to larger herds. Another observational tool, reproductive tract score (RTS), is a useful predictor of heifer fertility [102]. There is a positive correlation between high RTSs in heifers and percentage of heifers conceiving by artificial insemination [103]. RTS is a subjective estimate of sexual maturity based on ovarian follicular development and diameter of the uterine horns. An RTS of 1 is assigned to heifers with infantile tracts, as indicated by small, toneless uterine horns and small ovaries devoid of significant structures. Heifers with an RTS of 1 are likely the furthest from puberty at the time of examination. Heifers assigned an RTS of 2 are thought to be closer to puberty than those scoring 1, due primarily to larger uterine horns and ovaries. Those heifers assigned an RTS of 3 are thought to be on the verge of estrous cyclicity based on uterine tone and palpable follicles. Heifers assigned a score of 4 are considered to be cycling, as indicated by uterine tone and size, coiling of the uterine horns, and presence of a preovulatory‐sized follicle. Heifers assigned an RTS of 4 do not have an easily distinguished corpus luteum. Heifers with an RTS of 5 are similar to those scoring 4 except for the presence of a palpable corpus luteum [104].

      1 1 Robinson, T. and Shelton, J. (1977). Reproduction in cattle. In: Reproduction in Domestic Animals, 3e (eds. H.H. Cole and P.T. Cupps), 433–454. New York;: Academic Press.

      2 2 Donaldson, L., Bassett, J., and Thorburn, G. (1970). Peripheral plasma progesterone concentration of cows during puberty, oestrous cycles, pregnancy and lactation, and the effects of under‐nutrition or exogenous oxytocin on progesterone concentration. J. Endocrinol. 48: 599–614.

      3 3 Jones, E., Armstrong, J., and Harvey, R. (1991). Changes in metabolites, metabolic hormones, and luteinizing hormone before puberty in Angus, Braford, Charolais, and Simmental heifers. J. Anim. Sci. 69: 1607–1615.

      4 4 Curtis, G., McGregor, C., Jones, D., and Grove‐White, D. (2018). The impact of early life nutrition and housing on growth and reproduction in dairy cattle. PLoS One 13 (2): e0191687.

      5 5 Moran, C., Quirke, J., and Roche, J. (1989). Puberty in heifers: a review. Anim. Reprod. Sci. 18: 167–182.

      6 6 Ramirez, D. and McCann, S. (1963). Comparison of the regulation of luteinizing hormone (LH) secretion in immature and adult rats. Endocrinology 72: 452–464.

      7 7 Levasseur, M.‐C. (1979). Thoughts on puberty. The gonads. Ann. Biol. Anim. Biochim. Biophys. 19: 321–335.

      8 8 Bettendorf, M., de Zegher, F., Albers, N. et al. (1999). Acute N‐methyl‐D,L‐aspartate administration stimulates the luteinizing hormone releasing hormone pulse generator in the ovine fetus. Horm. Res. 51: 25–30.

      9 9 Hassaneen, A., Naniwa, Y., Suetomi, Y. et al. (2016). Immunohistochemical characterization of the arcuate kisspeptin/neurokinin B/dynorphin (KNDy) and preoptic kisspeptin neuronal populations in the hypothalamus during the estrous cycle in heifers. J. Reprod. Dev. (5): 471–477.

      10 10 d'Anglemont de Tassigny, X., Ackroyd, K., Chatzidaki, E., and Colledge, W. (2010). Kisspeptin signaling is required for peripheral but not central stimulation of gonadotropin‐releasing hormone neurons by NMDA. J. Neurosci. 30: 8581–8590.

      11 11 Schams, D., Schallenberger, E., Gombe, S., and Karg, H. (1981). Endocrine patterns associated with puberty in male and female cattle. J. Reprod. Fertil. Suppl. 30: 103–110.

      12 12 Madgwick, S., Evans, A., and Beard, A. (2005). Treating heifers with GnRH from 4 to 8 weeks of age advanced growth and the age at puberty. Theriogenology 63: 2323–2333.

      13 13 Day, M., Imakawa, K., Garcia‐Winder, M. et al. (1984). Endocrine mechanisms of puberty in heifers: estradiol negative feedback regulation of luteinizing hormone secretion. Biol. Reprod. 31: 332–341.

      14 14 Anderson, W., Forrest, D., Goff, B. et al. (1986). Ontogeny of ovarian inhibition of pulsatile luteinizing hormone secretion in postnatal Holstein heifers. Domest. Anim. Endocrinol. 3: 107–116.

      15 15 Moseley, W., Dunn, T., Kaltenbach, C. et al. (1984). Negative feedback control of luteinizing hormone secretion in prepubertal beef heifers at 60 and 200 days of age. J. Anim. Sci. 58: 145.

      16 16 Day, M., Imakawa, K., Wolfe, P. et al. (1987). Endocrine mechanisms of puberty in heifers. Role of hypothalamo‐pituitary estradiol receptors in the negative feedback of estradiol on luteinizing hormone secretion. Biol. Reprod. 37: 1054–1065.

      17 17 Kinder, J., Day, M., and Kittok, R. (1987). Endocrine regulation of puberty in cows and ewes. J. Reprod. Fertil. Suppl. 34: 167–186.

      18 18 Gonzalez‐Padilla, E., Wiltbank, J., and Niswender, G. (1975). Puberty in beef heifers. I. The interrelationship between pituitary, hypothalamic and ovarian hormones. J. Anim. Sci. 40: 1091–1104.

      19 19 Foster, D., Yellon, S., and Olster, D. (1985). Internal and external determinants of the timing of puberty in the female. J. Reprod. Fertil. 75: 327–344.

      20 20 Cardoso, R., Alves, B., Sharpton, S. et al. (2015). Nutritional programming of accelerated puberty in heifers: involvement of pro‐opiomelanocortin neurones in the arcuate nucleus. J. Neuroendocrinol. 26 (8): 647–657.

      21 21 Garverick, H. and Smith, M. (1986). Mechanisms associated with subnormal luteal function. J. Anim. Sci. 62: 92–105.

      22 22 Garverick, H., Zollers, W., and Smith, M. (1992). Mechanisms associated with corpus luteum lifespan in animals having normal or subnormal luteal function. Anim. Reprod. Sci. 28: 111–124.

      23 23 Hunter, M. (1991). Characteristics and causes of the inadequate corpus luteum. J. Reprod. Fertil. Suppl. 43: 91.

      24 24 Wathes, D. and Lamming, G. (1995). The oxytocin receptor, luteolysis and the maintenance of pregnancy. J. Reprod. Fertil. Suppl. 49: 53.

      25 25 McLeod, B., Peters, A., Haresign, W., and Lamming, G. (1985). Plasma LH and FSH responses and ovarian activity in prepubertal heifers treated with repeated injections of low doses of GnRH for 72 h. J. Reprod. Fertil. 74: 589–596.

      26 26 Seidel, G., Larson, L., and Foote, R. (1971). Effects of age and gonadotropin treatment on superovulation in the calf. J. Anim. Sci. 33: 617–622.

      27 27 Staigmiller, R., Short, R., and Bellows, R. (1979). Induction of LH surges with 17β estradiol in prepuberal beef heifers: an age dependent response. Theriogenology 11: 453–459.

      28 28 Desjardins, C. and Hafs, H. (1969). Maturation of bovine female genitalia from birth through puberty. J. Anim. Sci. 28: 502–507.

      29 29 Erickson, B. (1966). Development and senescence of the postnatal bovine ovary. J. Anim. Sci. 25: 800–805.

      30 30 Sorensen AM. (1959) causes and prevention of reproductive failures in dairy cattle. influence of underfeeding and overfeeding on growth and development of Holstein heifers. Vol. 936 of Bulletin of the Cornell University Agricultural Experiment Station. Ithaca, NY: Cornell University.

      31 31 Laster, D., Smith, G., Cundiff, L., and Gregory, K. (1979). Characterization of biological types of cattle (cycle II) II. Postweaning growth and puberty of heifers. J. Anim. Sci. 48: 500–508.

      32 32 Short, R. and Bellows, R. (1971). Relationships among weight gains, age at puberty and reproductive performance in heifers. J. Anim. Sci. 32: 127–131.

      33 33 Hall, J., Staigmiller, R., Bellows, R. et al. (1995). Body composition and metabolic profiles associated