Progress 11/04/02 to 10/31/07
Outputs
OUTPUTS: There is little information on how Dorper x St. Croix White (DRPX)crossbred ewes will perform under tropical conditions. The objective of this study was to evaluate production traits of DRPX ewes in an accelerated lambing system. The DRPX ewes (n=26) were compared to an established St. Croix White flock (STX; n=40) over a period of 2 yr (4 lamb crops; 163 births). The DRPX ewes were introduced into the flock for their first lambing in March 2004. Subsequent lamb crops were produced in November 2004, July 2005 and March 2006. The STX ewes were older than DRPX ewes at the first lambing (4.2 vs. 1.0 yr, respectively). Overall there was no difference in the proportion of DRPX and STX ewes that were exposed to rams that lambed (88.7 vs. 80.4 % respectively). There was no difference between STX and DRPX ewes in weight at breeding (42.4 vs. 43.6 kg,respectively) or weaning (42.5 vs. 45.4 kg, respectively). Number of lambs born per ewe lambing was greater in STX than in DRPX ewes (1.9 vs. 1.5 lambs, respectively). Number of lambs born increased in DRPX ewes from 1.2 to 1.8 between the first and third lamb crops but there was no change in the STX ewes during this time (2.1 vs. 1.9 lambs, respectively). Number of lambs weaned increased in DRPX ewes from 1.2 to 1.8 between the first and third lamb crops but there was no change in the STX ewes during this time (1.8 vs. 1.4 lambs, respectively). Weaning percent was higher in DRPX than STX ewes (95.2 vs. 83.6%, respectively). Litter weaning weight was higher in DRPX than in STX ewes (22.7 vs. 19.7 kg, respectively). Even though the DRPX ewes had fewer lambs born than STX ewes they produced heavier litter weaning weights. These results indicate that DRPX ewes can be used in an accelerated lambing system under tropical conditions. PARTICIPANTS: The PI, a Research Analyst and two field staff worked on managing the sheep and collecting the data. An undergraduate student was involved in some aspects of the project by using the animals to conduct research projects as part of her directed independent study. TARGET AUDIENCES: Target audiences would include sheep producers in the U.S. Virgin Islands, as well as the wider Caribbean. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Local producers have incorporated Dorper genetics into their sheep flocks and are able to manage the crossbred animals efficiently and in the same way they manage the indigenous sheep breeds. There is a high demand for the Dorper crossbred sheep because of the larger and faster growing lambs they produce. Producers are being cautioned though, to not crossbreed all of their indigenous sheep so that they will always have some purebred animals to incorporate into their crossbreeding program.
Publications
- McSween, V., R.W. Godfrey, R.E. Dodson and A.J. Weis. 2005. Evaluating the relationship between temperament and production traits of hair sheep. J. Animal Sci. 83(Suppl.2):19.
- Weiss, S.A., R.C. Ketring and R.W. Godfrey. 2007. Evaluation of alternative small ruminant finishing systems for the tropics. J. Animal Sci. 85(Suppl. 1):661.
- Godfrey, R.W., R.E. Dodson, M.C. Vinson and R.C. Driscoll. 2007. Production traits of Dorper crossbred ewes in an accelerated lambing system in the tropics. J. Animal Sci. 85(Suppl. 2):39.
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Progress 01/01/06 to 12/31/06
Outputs
Dorper x St Croix White (DRPX) ewes (n=26) were compared to an established St. Croix White flock (STX;n=40) for 4 lamb crops (163 births). The DRPX ewes were introduced into the flock for their first lambing in March 2004. Subsequent lamb crops were produced in November 2004, July 2005 and March 2006. The STX ewes were older than DRPX ewes at the first lambing (4.2 vs. 1.0 yr, respectively). Overall there was no difference in the proportion of DRPX and STX ewes that were exposed to rams that lambed (88.7 vs. 80.4 percent, respectively). There was no difference between STX and DRPX ewes in weight at breeding (42.4 vs. 43.6 kg, respectively) or weaning (42.5 vs. 45.4, respectively). Number of lambs born per ewe lambing was greater in STX than in DRPX ewes (1.9 vs. 1.5 lambs, respectively). Number of lambs born increased in DRPX ewes from 1.2 to 1.8 between the first and third lamb crops but there was no change in the STX ewes during this time (2.1 vs. 1.9 lambs,
respectively). Number of lambs weaned increased in DRPX ewes from 1.2 to 1.8 between the first and third lamb crops but there was no change in the STX ewes during this time (1.8 vs. l.4 lambs, respectively). Weaning percent was higher in DRPX than STX ewes (95.2 vs. 83.6 %, respectively). Litter weaning weight was higher in DRPX than in STX ewes (22.7 vs. 19.7 kg, respectively). Even though the DRPX ewes had fewer lambs born than STX ewes they produced heavier litter weaning weights. These results indicate that DRPX ewes can be used in an accelerated lambing system under tropical conditions.
Impacts
There is no impact to report this year.
Publications
- Dodson, R.E. and R.W. Godfrey. 2005. The use of Dorper crossbred ewes in an accelerated lambing and extensive management system in the tropics. J.Animal Sci. 83(Suppl. 1):343.
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Progress 01/01/05 to 12/31/05
Outputs
Dorper crossbred ewes were bred to the same breed rams twice during the year and data was collected, but due to staffing vacancies (2 support positions vacant for most of the year) and added duties of the Animal Scientist (serving as Acting Director of AES) there was no analysis of the data during this year. The technical support issue is being addressed and replacements are being hired. The administrative duties of the PI have decreased after the return of the Director in December 2005.
Impacts
There is no impact to report for this year.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/30/04
Outputs
Dorper sheep are being used in the U.S. Virgin Islands for crossbreeding with the local hair sheep. The objective of this study was to evaluate the production traits of St. Croix White X Dorper (DPRX) ewes in an extensive management and accelerated lambing system. The DPRX ewes (n=14;9.6 mo of age) were compared to an established flock of Barbados Blackbelly (BB;n=22; 38.2 mo of age) and St. Croix White (STX; n=21;50.8 mo of age) ewes managed on guinea grass pastures. Breeding occurred in October 2003 (BRD1) and June 2004 (BRD2) using DRPX, BB and STX rams for 35 d. Ovulation rate was determined by laparoscopy on d 7 to 9 after mating. Lambs were born in March 2004 (LMB1)and November 2004 (LMB2). On 7, 21, 35,49 and 63 d of lactation 24-h milk production was measured. Lambs were weaned at 63 d of age in May 2004 (WEAN1) and January 2005 (WEAN2). Ovulation rate at BRD1 and BRD2 was lower in DRPX than in BB or STX ewes (1.1 vs. 1.6 vs 1.9, respectively). Number of lambs
born at LMB1 was higher for STX than for BB or DRPX ewes (2.1 vs.1.7 vs. 1.2, respectively) but there was no difference at LMB2 (1.6). The DRPX ewes had fewer multiple births at LMB1 than BB or STX ewes (18.2 vs. 63.6 vs. 90.5%, respectively) but not at LMB2. Litter birth weight was lower for DRPX than for BB or STX ewes at LMB1 (3.4 vs. 4.9 vs. 6.2 kg, respectively) but not at LMB2. There was no difference in litter weaning weight at WEAN1 but at WEAN2 it was greater in DRPX than in BB or STX ewes (20.9 vs. 14.8 vs. 16.3 kg, respectively). Milk production, reported as area under the lactation curve, was similar among breeds during both lactations (51034.7 units).
Impacts
These results show that it is possible to incorporate Dorper crossbred ewes into an accelerated lambing and extensive management system and achieve production levels that are similar to those of local hair sheep under tropical conditions.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
St. Croix White (STX; n=11), Barbados Blackbelly (BB; n=22) and Dorper X STX (DX; n=11) ewes were bred to rams of the same breeds during a 35-d period. Pregnancy rate was not different among STX, BB and DX ewes (91.7, 95.7 and 84.6%, respectively). The proportion of ewes having twin lambs was higher for STX than for DX (90.9 vs. 18.2% respectively) with BB being intermediate (59.1%). All breeds had 100% live births with no stillborn lambs. The DX ewes were younger at the time of breeding than either the STX or BB ewes (0.7 vs. 3.7 vs. 3.1 yr of age, respectively). When adjusted for age of ewe at breeding, total litter birth weight was lowest in DX ewes compared to BB or STX ewes (3.4 vs 4.9 vs 5.6 kg respectively) and DX ewes had fewer lambs per ewe lambing than either STX or BB ewes (1.1 vs 1.9 vs 1.7 lambs, respectively). The ratio of total litter birth weight to ewe weight at lambing was lower in DX ewes compared to STX or BB ewes (0.08 vs 0.11 vs 0.12,
respectively). Birth weight of individual lambs, adjusted for litter size, was lower for DX lambs than for STX and BB lambs (2.6 vs 2.9 vs 2.9 kg, respectively). When adjusted for ewe weight at the time of breeding, ewe weight at lambing was lowest in BB and highest in STX with DX being intermediate (42.4 vs 44.9 vs 46.9 kg, respectively).
Impacts
There is no measurable impact of this project yet because it is still in the early stages of progress.
Publications
- No publications reported this period
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