Production traits of St. Croix White and Dorper x St. Croix ... - Inra
Production traits of St. Croix White and Dorper x St. Croix ... - Inra
Production traits of St. Croix White and Dorper x St. Croix ... - Inra
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R.W. Godfrey, R.E. Dodson <strong>and</strong> R.C. Ketring<br />
University <strong>of</strong> the Virgin Isl<strong>and</strong>s,<br />
Agricultural Experiment <strong>St</strong>ation,<br />
<strong>St</strong>. <strong>Croix</strong>, VI
Background<br />
• The Sheep research Facility at the University <strong>of</strong> the Virgin Isl<strong>and</strong>s<br />
Agricultural Experiment <strong>St</strong>ation was established in 1986<br />
• The flock originally consisted <strong>of</strong> <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> <strong>and</strong> Barbados Blackbelly<br />
hair sheep, <strong>and</strong> a small flock <strong>of</strong> Gulf Coast Native wool sheep was kept for a<br />
few years to evaluate parasite tolerance<br />
• Hair sheep in the tropics do not exhibit seasonal breeding patterns like<br />
most breeds <strong>of</strong> wool sheep in temperate regions making them very well<br />
suited for use in accelerated lambing systems<br />
• Seasonal pattern <strong>of</strong> rainfall in the USVI <strong>and</strong> limited l<strong>and</strong> area make pasture<br />
management a critical aspect <strong>of</strong> small ruminant farm management
Background<br />
• Breeds <strong>of</strong> hair sheep in the Caribbean produce relatively small lambs with<br />
light carcass weights at slaughter<br />
• Previous attempts in our lab to increase carcass weight by crossing with<br />
wool breeds have met with limited success<br />
• Suffolk X <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> lambs had higher average daily gain but lower<br />
feed efficiency when compared to purebred <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> lambs<br />
(Godfrey <strong>and</strong> Collins, 1999)<br />
• Lamb mortality <strong>of</strong> ¼ Suffolk x ¾ <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> lambs was 57.1%<br />
compared to 33.3% for <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> lambs while grazing gunieagrass<br />
pasture during the rainy season (Godfrey et al., 2000)<br />
• Therefore, we saw the need for evaluation <strong>of</strong> other breeds to be crossed<br />
with indigenous hair sheep
Introduction <strong>of</strong> <strong>Dorper</strong> Sheep<br />
PROS<br />
• Hair type sheep<br />
• Developed in South Africa<br />
• Adapted to hot climate<br />
• Heavy muscled<br />
CONS<br />
• Lack parasite tolerance <strong>of</strong> hair sheep<br />
• Not adapted to humid tropics<br />
• Expensive to purchase purebreds<br />
• Not as prolific as hair sheep
<strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> Crossbreds<br />
• <strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> lambs grow faster <strong>and</strong> yield heavier carcasses than<br />
<strong>St</strong>. <strong>Croix</strong> <strong>White</strong> lambs when they are raised on either a concentrate or<br />
forage ration after weaning (Dodson et al., 2005; Godfrey <strong>and</strong> Weis, 2005)<br />
• There were some issues with parasite susceptibility <strong>of</strong> the crossbred lambs<br />
(Dodson et al., 2005)
Caveat<br />
• Many farmers are using <strong>Dorper</strong> to crossbreed with local breeds <strong>of</strong> sheep<br />
• Taking advantage <strong>of</strong> increased growth rates, higher feed efficiency <strong>and</strong><br />
better carcass quality<br />
• Be careful not to wipe out local breeds <strong>of</strong> sheep by crossbreeding<br />
• Local hair breeds still have a place in the industry<br />
• Prolificacy<br />
• Hardiness<br />
• Parasite tolerance
Objective<br />
• The objective <strong>of</strong> this study was to compare production <strong>traits</strong> <strong>of</strong><br />
<strong>St</strong>. <strong>Croix</strong> <strong>White</strong> <strong>and</strong> <strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes managed in<br />
an extensive management <strong>and</strong> accelerated lambing system in<br />
the tropics.
Animals<br />
•The <strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes (DRPX; n = 17-25) were<br />
compared to an established <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> flock (STX; n = 20-<br />
27) for 6 lamb crops (387 lambings)<br />
•The DRPX ewes were bred in October 2003 for their first<br />
lambing in March 2004<br />
•Subsequent lamb crops were produced in November 2004, July<br />
2005, March 2006, November 2006 <strong>and</strong> July 2007<br />
•The STX ewes were older than DRPX ewes at the March 2004<br />
lambing (3.5 vs. 1.1 yr, respectively)
Management<br />
•Ewes grazed guinea grass (Panicum maximum) pastures at<br />
a stocking rate <strong>of</strong> 7-8 ewes/ha in a rotational grazing<br />
system during breeding, gestation <strong>and</strong> lactation<br />
•Single sire breeding for 35 d in Oct 2003, June 2004, Feb<br />
2005, Oct 2005, Jun 2006 <strong>and</strong> Feb 2007<br />
•Same breed rams used at a ram:ewe ratio <strong>of</strong> ~1:20<br />
•Lambs weaned at 63 d <strong>of</strong> age
JAN<br />
DEC<br />
FEB<br />
BREED<br />
LAMB<br />
NOV<br />
MAR<br />
LAMB<br />
BREED<br />
OCT<br />
APR<br />
SEP<br />
MAY<br />
AUG<br />
JUL<br />
LAMB<br />
JUN<br />
BREED
Results
Litter birth weight<br />
7<br />
6<br />
b<br />
c<br />
DRPX<br />
STX<br />
a,b P < 0.006<br />
c,d P < 0.003<br />
Breed x Time P < 0.003<br />
5<br />
d<br />
4<br />
a<br />
3<br />
2<br />
1<br />
0<br />
Mar-04 Nov-04 Jul-05 Mar-06 Nov-06 Jul-07<br />
Lambing
Litter size at birth<br />
2.5 DRPX<br />
STX<br />
b<br />
a,b P < 0.0002<br />
d c,d P < 0.02<br />
2.0<br />
Breed x Time P < 0.008<br />
c<br />
1.5<br />
a<br />
1.0<br />
0.5<br />
0.0<br />
Mar-04 Nov-04 Jul-05 Mar-06 Nov-06 Jul-07<br />
Lambing
Litter weaning weight<br />
30<br />
25<br />
b<br />
c<br />
DRPX<br />
STX<br />
a,b P < 0.02<br />
c,d P < 0.0001<br />
Breed x Time P < 0.0001<br />
a<br />
20<br />
d<br />
15<br />
10<br />
5<br />
0<br />
Mar-04 Nov-04 Jul-05 Mar-06 Nov-06 Jul-07<br />
Lambing
Litter size at weaning<br />
2.5 DRPX<br />
STX<br />
a,b P < 0.004<br />
b<br />
c,d P < 0.02<br />
2.0<br />
d<br />
Breed x Time P < 0.005<br />
1.5<br />
a<br />
c<br />
1.0<br />
0.5<br />
0.0<br />
Mar-04 Nov-04 Jul-05 Mar-06 Nov-06 Jul-07<br />
Lambing
Ewe Efficiency<br />
(litter weaning weight/ewe wt at weaning)*100<br />
60<br />
c<br />
DRPX<br />
STX<br />
a,b P < 0.03<br />
c,d P < 0.0001<br />
Breed x Time P < 0.0004<br />
a<br />
Efficiency, %<br />
50<br />
40<br />
b<br />
d<br />
30<br />
Mar-04 Nov-04 Jul-05 Mar-06 Nov-06 Jul-07<br />
Lambing
Weaning rate<br />
100<br />
80<br />
DRPX<br />
STX<br />
Percent<br />
60<br />
40<br />
20<br />
0<br />
Full<br />
Weaning Rate<br />
Partial
Summary <strong>of</strong> production <strong>traits</strong> <strong>of</strong> <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> <strong>and</strong><br />
<strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes<br />
Ewe Breed<br />
<strong>St</strong>. <strong>Croix</strong> <strong>White</strong> <strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> P<br />
Number <strong>of</strong> lambs born 1.8 0.1 1.6 0.1 0.03<br />
Number <strong>of</strong> lambs weaned 1.6 0.1 1.5 0.1 n.s.<br />
Litter birth weight, kg 5.2 0.2 5.0 0.2 n.s.<br />
Litter weaning weight, kg 19.6 0.6 22.6 0.6 0.0004<br />
Ewe efficiency, % 46.8 1.5 50.2 1.4 0.09
Reproductive <strong>traits</strong> <strong>of</strong> <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> <strong>and</strong> <strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong><br />
<strong>White</strong> ewes<br />
Ewe Breed<br />
<strong>St</strong>. <strong>Croix</strong> <strong>White</strong> <strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> P<br />
Multiple lambs at birth, % 69.8 58.6 0.08<br />
Ewe fertility a , % 83.8 2.6 92.7 2.9 0.05<br />
Ewe prolificacy b , % 1.7 0.1 1.6 0.1 n.s.<br />
Ewe fecundity c 1.4 0.1 1.5 0.1 n.s.<br />
a<br />
Ewes lambing / ewes exposed<br />
b<br />
Lambs born / ewe lambing<br />
c<br />
Lambs born / ewe exposed
Summary<br />
• Even though the <strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes had fewer<br />
lambs born than <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes they produced heavier<br />
litter weaning weights<br />
• The <strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes were able to achieve<br />
production rates similar to <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes as they<br />
matured as shown by heavier litter weaning weights <strong>and</strong><br />
greater ewe efficiency<br />
• Within 1 lambing <strong>of</strong> being introduced into the flock the <strong>Dorper</strong><br />
x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes had production <strong>traits</strong> similar to those <strong>of</strong><br />
the <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes
Conclusion<br />
• These results indicate that <strong>Dorper</strong> x <strong>St</strong>. <strong>Croix</strong> <strong>White</strong> ewes can<br />
be used in an accelerated lambing system under tropical<br />
conditions <strong>and</strong> will achieve production rates similar, <strong>and</strong> even<br />
superior, to those <strong>of</strong> indigenous sheep breeds
Questions