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Genetic components for breeding system traits in Angus-Hereford
crossing
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L. M. Melucci, C. A. Mezzadra, E.L. Villarreal
Unidad Integrada Balcarce (Facultad de Ciencias Agrarias, Universidad
Nacional de Mar del Plata Estación Experimental Agropecuaria Balcarce,
Instituto Nacional de Tecnología Agropecuaria). 7620 Balcarce,
Argentina. |
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Click to enlarge |
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Introduction
Crossbreeding between Angus (A) and Hereford (H)
breeds is widely used in the Pampean Region of Argentina, improving
meat production both through increasing fertility and growth. A
crossbreeding experiment was carried out in order to estimate genetic
components for productivity of the cow-calf system and to obtain
guidelines for using specific crossings under grazing conditions.
Objectives
The objectives of this study were to estimate:
- the difference of direct additive (goA goH)
and maternal (gmA gmH) genetic effects; individual (hoAH) and
maternal heterosis (hmAH); and losses due to individual epistatic
recombinations (roAH) for calf birth weight (BW) and weaning weight
(WW180)
- the difference of breed direct additive (goA goH) and maternal (gmA
gmH) genetic effects and individual heterosis (hoAH) for cow weight
at weaning (CWW) in a crossbreeding system between A and H
- Productivity (PROD) of the F1 dams at weaning when mated to A, H
and Limousin (L) sires compared with PROD of purebred dams.
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Materials
Experimental site: Unidad Integrada Balcarce (37º
45'S; 58º 15'W; 130 m above sea level.) humid-temperate climate with
annual mean temperature of 14ºC and 890 mm average annual rainfall.
Animals and management: Calving season: from August to October.
Animals grazed cultivated pastures all the year round. Calves had no
access to creep feeding; and were weaned at 180 days of age.
139 A, 160 H, 56AH and 135 HA cows, (breed of sire first) were sired
with 20 A, 22 H, 4 AH, 5 HA and 4 L bulls, producing 1263 progeny
calves. |
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Statistical analyses.
- Multiple trait, derivative free restricted maximum likelihood
methodology (MTDFREML) for:
BW - WW180 = µ + Y + BM + S + A + CG + D + M + P + b(cw) + å
CWW = µ + Y + BM + A + BG + S + L + D + P + å
Where:
Fixed effects: Y (year), BM (birth month), S (sex), A (age of dam), CG
(calf genotype), BG (breed group), L (lactation status effect).
Random effects: D (direct), M (maternal), P (permanent) effects; å
(residual). For BW, cow weight at parturition (cw) was included as
covariate.
GLM procedure of SAS (1996) for:
PROD= µ + Y + MG + S + A + BM + å
Where:
PROD: calf WW180 / CWW
MG: mating group
Parameter estimations. Contrasts for the estimation of components were:
goA goH
= A H + AH - HA
gmA gmH = HA - AH
hoAH= ½ [ ( AH + HA) ( A + H)]
hmAH = ½ {[ A(AH) + A(HA) + H(AH) + H(HA)] [ (AH)2 + (HA)2 ] ½ [ A + H
+ AH + HA]}
roAH = 2 [ (AH)2 + (HA)2 ] - [ A(AH) + A(HA) + H(AH) + H(HA)] |
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Results
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Direct additive and maternal genetic effects,
individual and
maternal heterosis and loss by epistatic recombinations effects in
crossings between Angus and Hereford for birth weight (BW), progeny
weaning weight (WW180) and cow weight at weaning (CWW).
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Contrasts (1) |
BW±SE (kg) |
WW180±SE (kg) |
CWW±SE (kg) |
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goA
- goH |
-3.97 ± 0.49* |
-11.17 ± 4.09* |
-45.33 ± 10.28* |
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gmA
- gmH |
0.82 ± 0.82 |
8.16 ± 5.03 |
-0.62 ± 7.13 |
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ho |
0.91 ± 0.24* |
6.63 ± 1.99* |
27.62 ± 4.36* |
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hm |
0.04 ± 0.75 |
8.47 ± 6.04 |
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roAH |
0.35 ± 2.32 |
2.94 ± 19.49 |
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(1) see text
*P< 0.05 if (2* SE) <
contrast |
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Click on the figure to enlarge |
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Means and standard deviation for cow weight at
weaning
(CWW) and 180 day adjusted progeny weaning weight (WW180) by mating
group. |
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Mating group (Sire x dam) |
CWW (kg) |
WW180 (kg) |
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A x A |
389 ± 45 |
131 ± 16 |
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H x H |
414 ± 43 |
134 ± 18 |
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A x (AH) and A x (HA) |
430 ± 51 |
145 ± 17 |
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H x (AH) and H x (HA) |
434 ± 53 |
148 ± 19 |
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A x H |
418 ± 43 |
136 ± 18 |
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H x A |
378 ± 45 |
142 ± 16 |
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L x (AH) and L x (HA) |
432 ± 47 |
152 ± 22 |
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(AH) x (AH) and (HA) x (HA) |
462 ± 54 |
150 ± 18 |
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Number of births by dam and sire breed.
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Dam breed |
Sires (1) |
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A |
H |
L |
AH |
HA |
Total |
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A |
215 |
153 |
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368 |
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H |
123 |
243 |
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366 |
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AH |
41 |
44 |
61 |
12 |
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158 |
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HA |
75 |
99 |
175 |
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22 |
371 |
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Total |
454 |
539 |
236 |
12 |
22 |
1263 |
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(1) A: Angus; H: Hereford; L:
Limousin; AH: sire A and dam H; HA: sire H and dam A. |
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Conclusions
Direct effects were favourable to H in all traits.
Important individual heterosis effects were found for calf birth
weight and weaning weight as well as for cow weaning weight.
Under the nutritional conditions here described, the higher F1 cow
weights at weaning affected unfavourably the breeding system so that
productivity was higher for A dams rearing F1 calves than for F1 dams
rearing three-breed crossbred calves. |
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Proyecto FONCYT: 08-04156. Préstamo BID 1201/OC-AR. Proyecto A040 (UNMDP);
INTA. |
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