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Exploration of the Hypothalamic-Pituitary-Adrenal Axis to Improve Animal Welfare by Means of Genetic Selection: Lessons from the South African Merino.

Hough D, Swart P, Cloete S - Animals (Basel) (2013)

Bottom Line: It is a difficult task to improve animal production by means of genetic selection, if the environment does not allow full expression of the animal's genetic potential.This concept may well be the future for animal welfare, because it highlights the need to incorporate traits related to production and robustness, simultaneously, to reach sustainable breeding goals.If genetic selection for superior HPAA responses to stress is possible, then it ought to be possible to breed robust and easily managed genotypes that might be able to adapt to a wide range of environmental conditions whilst expressing a high production potential.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, Stellenbosch University, Stellenbosch 7602, South Africa. houghdenise@gmail.com.

ABSTRACT
It is a difficult task to improve animal production by means of genetic selection, if the environment does not allow full expression of the animal's genetic potential. This concept may well be the future for animal welfare, because it highlights the need to incorporate traits related to production and robustness, simultaneously, to reach sustainable breeding goals. This review explores the identification of potential genetic markers for robustness within the hypothalamic-pituitary-adrenal axis (HPAA), since this axis plays a vital role in the stress response. If genetic selection for superior HPAA responses to stress is possible, then it ought to be possible to breed robust and easily managed genotypes that might be able to adapt to a wide range of environmental conditions whilst expressing a high production potential. This approach is explored in this review by means of lessons learnt from research on Merino sheep, which were divergently selected for their multiple rearing ability. These two selection lines have shown marked differences in reproduction, production and welfare, which makes this breeding programme ideal to investigate potential genetic markers of robustness. The HPAA function is explored in detail to elucidate where such genetic markers are likely to be found.

No MeSH data available.


Related in: MedlinePlus

Comparison of cortisol production in adult sheep adrenocortical cells incubated for 72 hours with 100 µM pregnenolone and 1 µM ACTH. Results are expressed as mean ± SEM of triplicate measurements for the adrenocortical cells (primary cultures) prepared from adult rams, representative of each selection line (H- vs. L-line) × CYP17 genotype group (homozygous WT1/WT1 vs. heterozygous WT1/WT2) (n = 2 animals of each group). The H-line is represented by a black line, the L-line represented by a grey line, whereas homozygous WT1/WT1 groups are represented by a solid line, and heterozygous WT1/WT2 groups by a broken line. Adapted from Hough [42].
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animals-03-00442-f002: Comparison of cortisol production in adult sheep adrenocortical cells incubated for 72 hours with 100 µM pregnenolone and 1 µM ACTH. Results are expressed as mean ± SEM of triplicate measurements for the adrenocortical cells (primary cultures) prepared from adult rams, representative of each selection line (H- vs. L-line) × CYP17 genotype group (homozygous WT1/WT1 vs. heterozygous WT1/WT2) (n = 2 animals of each group). The H-line is represented by a black line, the L-line represented by a grey line, whereas homozygous WT1/WT1 groups are represented by a solid line, and heterozygous WT1/WT2 groups by a broken line. Adapted from Hough [42].

Mentions: The genetic variability in adrenal function was obvious in a study by Hough [42], where primary cultures were prepared from the adrenal glands of H- and L-line Merino rams (Figure 2). Comparisons of adrenal steroidogenesis under unstimulated and ACTH-stimulated conditions over a period of 72 hours clearly indicated that the adrenocortical cells of H-line sheep produced significantly more (~4-fold) cortisol than L-line sheep throughout the experiment. This indicated that a great degree of variability in the HPAA function of the H- and L-lines resided within the adrenal function. The addition of cholera toxin or forskolin (mimics ACTH-mediated intracellular signalling pathway) instead of ACTH to these adrenocortical cell cultures showed no significant difference between the glucocorticoid responses of the H- and L-line. This observation indicated that the difference in glucocorticoid response between the H- and L-line is unlikely to reside within the ACTH-stimulated intracellular signalling pathway.


Exploration of the Hypothalamic-Pituitary-Adrenal Axis to Improve Animal Welfare by Means of Genetic Selection: Lessons from the South African Merino.

Hough D, Swart P, Cloete S - Animals (Basel) (2013)

Comparison of cortisol production in adult sheep adrenocortical cells incubated for 72 hours with 100 µM pregnenolone and 1 µM ACTH. Results are expressed as mean ± SEM of triplicate measurements for the adrenocortical cells (primary cultures) prepared from adult rams, representative of each selection line (H- vs. L-line) × CYP17 genotype group (homozygous WT1/WT1 vs. heterozygous WT1/WT2) (n = 2 animals of each group). The H-line is represented by a black line, the L-line represented by a grey line, whereas homozygous WT1/WT1 groups are represented by a solid line, and heterozygous WT1/WT2 groups by a broken line. Adapted from Hough [42].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494397&req=5

animals-03-00442-f002: Comparison of cortisol production in adult sheep adrenocortical cells incubated for 72 hours with 100 µM pregnenolone and 1 µM ACTH. Results are expressed as mean ± SEM of triplicate measurements for the adrenocortical cells (primary cultures) prepared from adult rams, representative of each selection line (H- vs. L-line) × CYP17 genotype group (homozygous WT1/WT1 vs. heterozygous WT1/WT2) (n = 2 animals of each group). The H-line is represented by a black line, the L-line represented by a grey line, whereas homozygous WT1/WT1 groups are represented by a solid line, and heterozygous WT1/WT2 groups by a broken line. Adapted from Hough [42].
Mentions: The genetic variability in adrenal function was obvious in a study by Hough [42], where primary cultures were prepared from the adrenal glands of H- and L-line Merino rams (Figure 2). Comparisons of adrenal steroidogenesis under unstimulated and ACTH-stimulated conditions over a period of 72 hours clearly indicated that the adrenocortical cells of H-line sheep produced significantly more (~4-fold) cortisol than L-line sheep throughout the experiment. This indicated that a great degree of variability in the HPAA function of the H- and L-lines resided within the adrenal function. The addition of cholera toxin or forskolin (mimics ACTH-mediated intracellular signalling pathway) instead of ACTH to these adrenocortical cell cultures showed no significant difference between the glucocorticoid responses of the H- and L-line. This observation indicated that the difference in glucocorticoid response between the H- and L-line is unlikely to reside within the ACTH-stimulated intracellular signalling pathway.

Bottom Line: It is a difficult task to improve animal production by means of genetic selection, if the environment does not allow full expression of the animal's genetic potential.This concept may well be the future for animal welfare, because it highlights the need to incorporate traits related to production and robustness, simultaneously, to reach sustainable breeding goals.If genetic selection for superior HPAA responses to stress is possible, then it ought to be possible to breed robust and easily managed genotypes that might be able to adapt to a wide range of environmental conditions whilst expressing a high production potential.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, Stellenbosch University, Stellenbosch 7602, South Africa. houghdenise@gmail.com.

ABSTRACT
It is a difficult task to improve animal production by means of genetic selection, if the environment does not allow full expression of the animal's genetic potential. This concept may well be the future for animal welfare, because it highlights the need to incorporate traits related to production and robustness, simultaneously, to reach sustainable breeding goals. This review explores the identification of potential genetic markers for robustness within the hypothalamic-pituitary-adrenal axis (HPAA), since this axis plays a vital role in the stress response. If genetic selection for superior HPAA responses to stress is possible, then it ought to be possible to breed robust and easily managed genotypes that might be able to adapt to a wide range of environmental conditions whilst expressing a high production potential. This approach is explored in this review by means of lessons learnt from research on Merino sheep, which were divergently selected for their multiple rearing ability. These two selection lines have shown marked differences in reproduction, production and welfare, which makes this breeding programme ideal to investigate potential genetic markers of robustness. The HPAA function is explored in detail to elucidate where such genetic markers are likely to be found.

No MeSH data available.


Related in: MedlinePlus