Progress 10/01/05 to 09/30/11
Outputs
OUTPUTS: The overall objective of this long-term grading-up project was to track changes in production traits as breed composition of the flock changed from Polypay (a traditional wool breed) to White Dorper (a hair breed). During the lifetime of the project, Polypay, 1/2 White Dorper x 1/2 Polypay, 3/4 White Dorper x 1/4 Polypay, 7/8 White Dorper x 1/8 Polypay, 15/16 White Dorper x 1/16 Polypay and White Dorper (genetic composition greater than 15/16 White Dorper)offspring were produced. Replacement ewes were subsequently selected from these six genetic types. Maternal and growth performance were measured and a random sample of lambs of each genetic type were harvested to evaluate carcass composition. In the final year of the project, ewes of each genetic type were mated to a third breed (Hampshire, a terminal sire breed) to evaluate lamb growth and carcass composition. Over the lifetime of the project, maternal, growth and carcass data were combined and final statistical analyses are in progress. Data (FAMACHA scores, fecal egg counts and packed cell volumes) collected for evaluation of interal parasite tolerance or resistance were analyzed. Results have been shared with researchers participating in a multi-state coordinating committee (NCERA-214) and were shared with producers from Kentucky and adjoining states through five field days, four producer schools each year, grazing workshops and radio programs. Also, data collection and analyses provided opportunities to train three graduate students and four undergraduate students. Two undergraduate research projects were conducted in association with this project. Animals of the resulting "new" breed were exhibited at state and national livestock shows and were made available for producers to purchase. PARTICIPANTS: D. K. Aaron and D. G. Ely were the principal investigators for this project. Oversight of mating plans and ewe/lamb management, data collection, statistical analysis and summarization were under the supervision of D. K. Aaron. Nutritional oversight and assistance with data collection was provided by D. G. Ely. E. Fink and B. T. Burden were responsible for the daily management of sheep and provided assistance with data collection. Three graduate students and four undergraduate students assisted with data collection and laboratory analyses during the lifetime of the project. Also, sheep from this project were used in conjunction with producer sheep management schools (Eweprofit Schools I, II and III), undergraduate research projects (2), undergraduate education (ASC 102-Applications of Animal Science and ASC 404G-Sheep Science), and other extension-related activities. TARGET AUDIENCES: The target audience for this project included sheep producers in Kentucky and adjoining states. Results from this project provided producers, who may have the desire to convert existing wool flocks to hair flocks in order to eliminate shearing and to combat parasite resistance problems in pasture-based management systems, with an unbiased, scientifically sound comparison between ewes and lambs of a wool breed (Polypay) with those of a hair breed (White Dorper) under a pasture-based production system. Results are delivered via producer schools, field days and industry meetings. Graduate students are trained to collect samples, conduct laboratory analyses and analyze data statistically. Undergraduate students conducting research projects as part of Honors or ag biotechnology programs and(or) enrolled in animal science courses are provided hands-on opportunities for learning sheep production techniques. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Efficient lean lamb production is the goal of commercial sheep producers. An important objective of this project was to compare carcass characteristics of wether lambs randomly selected for harvest from all those produced during the period 2003 through 2010. Percentage White Dorper breeding in the harvested lambs ranged from 0 (Polypay, n = 50), 50 (1/2 White Dorper, n = 50), 75 (3/4 White Dorper, n = 50), 87.5 (7/8 White Dorper, n = 35) to 93.75% or higher (White Dorper, n = 48). Each year lambs were born in April, creep fed on pasture, and weaned at 70 days of age. Postweaning, lambs were managed on pasture and supplemented with grain at 2 to 3% of body weight. Lamb carcasses were harvested at a live target weight of 54 kg. Weaning weights were heaviest for Polypay, 1/2 White Dorper and 3/4 White Dorper lambs and lightest for 15/16 White Dorper lambs. Postweaning average daily gain decreased as percent White Dorper breeding increased. There were no lamb genetic type differences in age at harvest but Polypay and 1/2 White Dorper lambs were heaviest (55.8, 56.2, 55.3, 54.4 and 50.8 kg for the 0, 50, 75, 97.5 and 93.75% or higher White Dorper, respectively) and had the heaviest carcasses (25.9, 26.9, 26.4, 26.2 and 25.4 kg, respectively). Rack weight increased as percent White Dorper breeding increased. There were no differences in leg or shoulder weights. Carcasses from 7/8 White Dorper lambs were fattest while carcasses from 15/16 White Dorper lambs were leanest. Longissimus muscle area was largest from 15/16 White Dorper and smallest for Polypay lambs. Yield grades were lowest for 15/16 White Dorper lambs. Results from this long-term project indicated carcasses of White Dorper lambs compare favorably with those of Polypay lambs for most traits. During the final year of the project, productivity of Polpay, White Dorper and White Dorper x Polypay ewes bred to Hampshire rams was evaluated. Lambing rates were lowest for White Dorper ewes. Total weight of lambs weaned was heaviest for Polpay (57.8 kg) and White Dorper x Polpay (52.6 kg) and lightest for White Dorper (46.7 kg). Polyay and White Dorper x Polypay ewes had higher condition scores than White Dorper ewes. Indicators of internal parasites (FAMACHA scores, packed cell volumes and fecal egg counts) were similar for all ewes. Lamb production of Polypay, White Dorper and F-1 cross ewes can be increased by using Hampshire rams. Lower production of the smaller White Dorper ewes may be offset by their natural shedding, which eliminates the need for shearing.
Publications
- Aaron, D. K., D. G. Ely, E. Fink, B. T. Burden, M. E. Hoar, M. M. Simpson, and A. K. Lundsford. 2011. Lean lamb production during the process of grading-up to hair sheep genetics. J. Anim. Sci. 89 (E-Suppl. 1):698.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: During the reporting period, Polypay, 1/2 White Dorper x 1/2 Polypay, 3/4 White Dorper x 1/4 Polypay, 7/8 White Dorper x 1/8 Polypay, 15/16 White Dorper x 1/16 Polypay and White Dorper (genetic composition greater than 15/16 White Dorper)offspring were produced as part of the grading-up mating scheme used to transform a traditional wool breed (Polypay) into a high percentage hair breed (White Dorper). Maternal and growth performance were measured and a random sample of lambs of each genetic type were harvested to evaluate carcass composition. Ewes of each genetic type were mated to a third breed (Hampshire, terminal sire breed) and will lamb in April. Maternal, growth and carcass data were combined with data collected during previous reporting years and statistical analyses are in progress. Data (FAMACHA scores, fecal egg counts and packed cell volumes) collected for evaluation of internal parasite tolerance or resistance were analyzed. Results obtained to date were discussed with researchers participating in a multi-state coordinating committee(NCERA-214) and were shared with producers from Kentucky and adjoining states through a field day, a grazing workshop, four producer schools and a radio program. Also, data collection and analysis provided opportunities to train two graduate students and two undergraduate students. Two undergraduate research projects are being conducted in association with this project. Animals of the resulting "new" breed were exhibited at state and national livestock shows and were made available for producers to purchase. PARTICIPANTS: D. K. Aaron and D. G. Ely are the principal investigators for this project. Oversight of mating plans and ewe/lamb management, data collection, analysis and summarization are under the supervision of D. K. Aaron. Nutritional oversight and assistance with data collection are provided by D. G. Ely. E. Fink and B. T. Burden are responsible for the daily management of sheep and provide assistance with data collection. Two graduate students and four undergraduate students assisted with data collection and laboratory analysis during the reporting period. Also, sheep from this project are used in conjunction with producer sheep management schools (Eweprofit Schools I, II, and III), undergraduate research projects (2), undergraduate education (ASC 102-Applications of Animal Science and ASC 404G-Sheep Science), and other extension-related activities. TARGET AUDIENCES: The target audience for this project includes sheep producers in Kentucky and adjoining states. Results from this project provide producers, who may desire to convert existing wool flocks to hair flocks in order to eliminate shearing and to combat parasite resistance problems in pasture-based management systems, with an unbiased, scientifically sound comparison between ewes and lambs of a wool breed (Polypay) with those of a hair breed (White Dorper) under a pasture-based production system. Results are delivered via producer schools, field days and industry meetings. Graduate students are trained to collect samples, conduct laboratory analysis and analyze data statistically. Undergraduate students conducting research projects as part of Honors or ag biotechnology programs and(or) enrolled in animal science courses (ASC 102, ASC 404G) are provided hands-on opportunities for learning sheep production techniques. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The FAMACHA system is designed to provide sheep producers with a tool for on-farm detection and treatment of Haemonchus contortus infection. One objective during this reporting period was to evaluate accuracy of the FAMACHA system for categorizing ewes on the basis of severity of anemia measured by packed cell volume (PCV). A total of 1,507 records were collected on Hampshire, Polypay and percentage White Dorper ewes from 2005 through 2009 and were analyzed during this reporting period. Eyelid scores based on color of the ocular conjunctiva (1=red to 5=white, anemic) were assigned using the FAMACHA card. Blood samples were collected and PCV were determined using a digital microhematocrit reader. Percentages of eyelid score values in each category (from 1 to 5) were 19, 38, 21, 10 and 2%, respectively. This verifies the theory that parasite problems in a flock are caused by 20% of the ewes in a typical flock. PCV decreased linearly as eyelid scores increased; however, the magnitude of change was dependent upon breed. Similarly, strength of the linear association between PCV and eyelid scores varied among breeds. Across breeds, measured PCV were higher than expected within each eyelid score category. Percentages of PCV exceeding the upper limit of the eyelid score category (from 1 to 5) were 93, 80, 92, 91 and 78%. Few PCV were below the expected lower limits in any eyelid score category. These data confirm the FAMACHA system will allow detection of anemic animals. However, if ewes with eyelid scores of 3, 4, and 5 are considered anemic, many non-anemic ewes will be treated for parasite infection. This may contribute to resistance of the parasite to currently used drugs. Finally, the association between eyelid score and PCV may be influenced by face color. Producers should be aware of this when assigning FAMACHA scores in black- versus white-faced ewes.
Publications
- Aaron, D. K., M. M. Simpson, D. G. Ely, E. Fink, B. T. Burden, M. E. Hoar and J. Farris. 2010. Accuracy of the FAMACHA system for estimating degree of Haemonchus contortus induced anemia in Hampshire, Polypay and percentage White Dorper ewes. J. Anim. Sci. 88 (E-Suppl. 2):580 (Abstract#755).
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Hair sheep germplasm was initially incorporated into a flock of Polypay (PP) ewes through White Dorper (WD) rams. This has been ongoing since 2005 via a grading-up mating scheme. A contemporary group of PP ewes, bred to PP rams, is being maintained as a control. Each year, ewes are exposed to rams for a 3-wk period beginning Nov 15. Ewes and lambs are maintained as a single flock, on pasture, until lambs are weaned at 70 d. Following weaning, lambs remain on pasture and are supplemented with a concentrate mix at 2% of their body weight until entrance into the breeding flock, marketing, or harvest (55 kg) at the University of Kentucky Abattoir. Multiple studies have been conducted in Phase I of this project to answer questions regarding maternal performance, parasite resistance or tolerance, coat characteristics, lamb growth and carcass merit of percentage WD sheep. Results of these studies have been presented to producers and industry personnel at the following: Kentucky Small Ruminant Grazing Conference (Lexington, Jan 6, 2009), National Sheep Industry Association Covention (San Diego, CA, Jan 21-24, 2009), 40th Annual Kentucky Sheeprofit Day (Versailles, May 21, 2009) Joint Annual Meeting of the Kentucky Sheep and Wool Producers Association and Kentucky Goat Producers Association (Frankfort, Oct 17, 2009), American Dorper Sheep Breeders' Society Annual Meeting, Louisville, KY, Nov 19, 2009. In addition, sheep were used to for producer education at three Eweprofit Schools. "Purebred" WD rams and ewes generated from the grading-up process were also made available, via sales, to producers for improving hair sheep germplasm in flocks throughout the U.S. PARTICIPANTS: D. K. Aaron and D. G. Ely are the principal investigators for this project. Oversight of mating plans and ewe/lamb management, data collection, analysis and summarization are under the supervision of D. K. Aaron. Nutritional oversight and assistance with data collection are provided by D. G. Ely. E. Fink and B. T. Burden are responsible for the daily management of sheep and provide assistance with data collection. Two graduate students and three undergraduate students assisted with data collection and laboratory analyses during this reporting period. Also, sheep from this project are used in conjunction with producer sheep management schools (Eweprofit Schools I, II, and III), undergraduate education (ASC 102-Applications of Animal Science and ASC 404G-Sheep Science), and other extension-related activities. TARGET AUDIENCES: The target audience for this project includes sheep producers in Kentucky and surrounding states. Results from this project provide producers, who may desire to convert existing wool flocks to hair flocks in order to eliminate shearing, with an unbiased, scientifically sound comparison between ewes and lambs of a wool breed (Polypay) with those of a hair breed (White Dorper) under a pasture-based production system. Outcomes are also made available to industry representatives for further dissemination. Results are delivered via producer schools, field days and industry meetings. Graduate students are trained to collect samples and conduct laboratory analyses. Undergraduate students enrolled in animal science courses (ASC 102, ASC 404G)are provided hands-on opportunities for learning sheep production techniques. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The following conclusions are drawn from results of maternal and growth/carcass studies completed during this reporting period: 1) Incorporation of White Dorper (WD) breeding into a Polypay (PP) flock can result in ewes that are almost as productive as ewes of the foundation breed, and that eventually do not have to be sheared. Pregnancy rates are similar across ewe genetic types but lambing rates decrease as percent WD breeding increases, litter weaning weights are heaviest for 1/2 WD ewes (51 kg) but decrease as percent WD increases, and ewe weights and body condition scores are similar (69 kg, 2.4/5.0)across genetic types. When differences in age and parity are considered, percentage WD ewes (younger) may be comparable to PP ewes (older). However, PP will remain the more productive maternal breed. 2) Postweaning performance of 1/2 WD lambs is superior to PP lambs. Higher percentage WD lambs grow slower; however, this is likely the result of a loss of heterosis. 3) Indicators of Hamonchus contortus (stomach worm or barber pole worm) infection are influenced by characteristics of the ewe, which may mean susceptibility or tolerance to infection is dependent on her genetic type and production status. Higher percentage WD ewes are less susceptible to infection based on lower fecal egg counts, higher packed cell volumes, and lower FAMACHA scores. 4) Carcasses of WD cross lambs are superior to PP lambs; they yield the highest amount of lean meat and have heavier loins and racks. Fat thickness is similar for PP and WD lambs but longissimus area is 4.1 sq cm larger (18.7 vs. 14.6) for WD lambs. This adds evidence to the assumption that WD is a meaty, carcass breed. Overall, these results imply producers who have existing wool flocks, but desire to switch to hair sheep to eliminate shearing, can do so by breeding rams of a hair breed to existing wool ewes in a grading-up mating scheme. This scheme allows a pasture-based operation to be ongoing during the grading-up process. Conversion to a WD flock from a wool flock results in ewes that do not have to be sheared, can be as productive as the parent flock, and may offer some resistance to stomach worm infestation. Lambs produced by these ewes are heavy at weaning, perform as well after weaning as parental flock lambs, and produce carcasses that are heavily muscled. Continued selection for growth rate and carcass merit will be important as the percentage of WD genetics increases.
Publications
- Aaron, D. K., Ely, D. G., Fink, E., and Burden, B. T. 2009. Grading-up to hair sheep genetics in a pasture-based production system. Page 50 to 52 in Proc. U.S. Sheep Research Programs, American Sheep Industry Assoc. Conv., San Diego, CA.
- Aaron, D. K., Ely, Ely, D. G., Fink, E., and Burden, B. T. 2009. Factors affecting indicators of Haemonchus contortus infection in Polypay and percentage White Dorper ewes. J. Anim. Sci. J. Anim. Sci. (E Suppl. 3):36.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Hair sheep germplasm was initially incorporated into a flock of Polypay (PP) ewes through White Dorper (WD) rams. This has been ongoing since 2003 via a grading-up mating scheme. A group of PP ewes, bred to PP rams, is being maintained as a control. Each year ewes are exposed to rams for a 3-week period beginning on Nov 15. A total of 9 PP and 9 WD rams have been used to date. Ewes and lambs are maintained as a single flock, on pasture, until lambs are weaned at 70 days. Ewes receive a daily supplement of 0.45 kg shelled corn/hd and lambs have access to a corn-based creep feed. Following weaning, lambs remain on pasture and are supplemented with a concentrate mix at 2% of their body weight until entrance into the breeding flock, marketing or harvest. Mulitple studies were conducted in 2008 as part of this project. PP and percentage WD wether lambs were used to 1) compare nutrient utilization of high-roughage and high-concentrate diets (Study 1), 2) compare carcass characteristics (Study 2), 3) measure phenoptyic relationships among growth and carcass traits (Study 3), and 4) evaluate expression of L-glutamate transporters and enzymes, which are essential to nitrogen and energy metabolism of growing animals (Study 4). In Study 1, n = 6 lambs of each of three genetic types [PP, 1/2 WD x 1/2 PP (1/2 WD), and 3/4 WD x 1/4 PP (3/4 WD)] were fed a high-roughage diet in Phase 1 and a low-roughage diet in Phase 2. Nutrient digestibilities and nitrogen retention values were calculated at the end of each phase. In Study 2, carcasses of PP (n = 26), 1/2 WD (n = 30), 3/4 WD (n = 28), 7/8 WD x 1/8 PP (7/8 WD; n = 12), and 15/16 WD x 1/16 WD (15/16 WD; n=6) wether lambs raised on pasture were harvested at a live target weight of 54 kg. Postweaning ADG, harvest weight. age at harvest, carcass weight and carcass composition were compared. These same data were used in Study 3 to estimate phenoptye correlations among growth and carcass traits. In Study 4, the effect (n = 6) of lamb genetic type (PP, 1/2 WD, and 15/16 WD) on L-glutamate transporters and enzymes by liver, kidney, longissimus dorsi, and subcutaneous fat was evaluated via immunoplot analysis on lambs harvested as part of Study 2. The goal of Study 4 was to determine if observed differences in carcass quality of 15/16 WD lambs could be explained by differences in relative content of glutamate metabolizing enzymes and transporters. PARTICIPANTS: Individuals who worked on this project included the two investigators (D. K. Aaron and D. G. Ely) and the research specialist (E. Fink) and research coordinator (B. T. Burden) located at the U. K. Animal Research Center (Sheep Unit). Also, two graduate students and five undergraduate students were trained in procedures and assisted with data collection and analysis. TARGET AUDIENCES: Sheep producers in Kentucky and across the United States are impacted by results obtained from studies conducted during this reporting period. An increasing number of sheep producers are considering incorporation of hair sheep genetics into traditional wool flocks. Research is needed to determine performance of hair breeds relative to wool breeds, and this project serves that need. Knowledge derived from these studies has impacted producers via Kentucky Sheep and Wool Producers Association meetings, small ruminant grazing conferences, university field days, producer schools, and popular press. One-on-one consultations with individual producers have used results obtained from this project. Observed breed differences have been used update classroom instruction (ASC 102: Applications of Animal Science and ASC 404:Sheep Science). PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In Study 1, genetic type did not significantly alter either dry matter or nitrogen digestiility of the high-roughage diet (Phase 1). However, 1/2 WD lambs had a tendency to retain a larger porion of the dietary nigtrogen then either PP or 3/4 WD, with PP lambs retaining the least amount. Dry matter and nitrogen digestibility of the high-concentrate diet (Phase 2) was significantly higher in 1/2 WD lambs than PP and 3/4 WD lambs, with 3/4 WD lambs having the lowest values. This lead to 1/2 WD lambs having the highest nitrogen retention. These results indicate 3/4 WD lambs may be able to use high-roughage diets more efficiently than PP, but the reverse may be true when high-concentrate diets are consumed. Theoretically, the improved dry matter and nitrogen digestibility of the 1/2 WD could translate into increased weight gain. The magnitude of this effect is dependent on quality of the diet fed and variation in genetic type. In Study 2, carcasses of WD crossbred lambs compared favorably with those of PP lambs for most traits. PP and 1/2 WD lambs were heaviest at harvest, and had the heaviest carcasses, but ages were similar for all genetic types. Rack weights increased as percent WD increased, and longissimus muscle area was largest for 15/16 WD and smallest for PP. Percentage of closely trimmed retail cuts was higher for 15/16 WD. These results indicate carcasses of 15/16 WD lambs produce more lean tissue than PP or lower percentage WD lambs. Phenoptyic correlations calculated in Study 3 show weak to moderately strong relationships among all growth and carcass traits. In general, correlations were homogeneous between PP and WD crosses. Finally, results of Study 4 show the increased carcass quality of 15/16 WD lambs is concomitant with an altered protein content (reduced alanine transaminase) of tested tissues and an increase in glutamate metabolism. Furthermore, the altered protein content was by under post-transciprtional control. Results from Study 4 are important becasue they directly link an observed change in phenoptye (carcass quality) to specific gene expression. Results from all four studies have been shared with other scientists at regional and national American Society of Animal Science Meetings and with producers at field days and conferences. Hair breeds have a place in the future of U.S. sheep production but research, such as the studies described herein, are necessary to determine their production niche.
Publications
- Lunsford, A. K. D. G. Ely, D. K. Aaron, M. M. Simpson, and R. A. Zinner. 2008. Nutrient utilization of Polypay and percentage White Dorper lambs fed a high roughage and a high concentrate diet. Sheep and Goat Res. J. 23:1-6.
- Aaron, D. K., D. G. Ely, E. Fink, B. T. Burden, and M. M. Simpson. 2008. Carcass composition of Polypay versus White Dorper crossbred lambs. J. Anim. Sci. 86 (E-Suppl. 3):30 (abstract).
- Aaron, D. K. D. G. Ely, E. Fink, B. T. Burden, M. M. Simpson, and A. K. Lunsford. 2008. Phenotypic correlations among growth and carcass traits of Polypay and White Dorper crossbred lambs. J. Anim. Sci. 86 (E-Suppl. 2):340 (abstract).
- Lunsford, A. K. K. R. Brown, S. F. Liao, D. K. Aaron, J. C. Matthews, D. G. Ely, and J. A. Boling. 2008. Carcass quality and relative content of glutamate metabolizing enzymes differ in Polypay and percentage Polypay-White Dorper lmabs. J. Anim. Sci. (E-Suppl. 2):563 (abstract).
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The sheep industry must reduce labor requirements and improve efficiency of lean lamb production if it is to remain economically viable. Traits that affect labor requirements include hardiness, parasite tolerance, and shedding of hair and wool to eliminate shearing. Traits that affect production efficiency include fertility, prolificacy, ewe and lamb vigor, maternal ability, and post-weaning lamb growth. Post-harvest traits affecting meat quality include fatness, muscling, and carcass yield. Meat quality is important to ensure an enjoyable eating experience by the consumer. This project evaluates lean lamb production of hair sheep (White Dorper) in a pasture-based production system. During the past year carcass data were summarized on 132 wether lambs differing in percentage White Dorper breeding and raised on pasture. This is one of the largest studies ever conducted comparing carcass data of hair (White Dorper) versus wool (Polypay) sheep; it shows carcasses of White
Dorper crossbred lambs compare favorably with those of Polypay lambs for most traits. These results were shared with sheep producers from Kentucky and surrounding states at the annual University of Kentucky Sheeprofit Day and at Eweprofit Schools in April, June, and October. Another important issue involves susceptibility to internal parasites. Ewes developed as part of this project have been used to demonstrate a management program for control of Haemonchus contortus infestation.
PARTICIPANTS: D. K. Aaron D. G. Ely E. Fink B. T. Burden
TARGET AUDIENCES: Results will be important to sheep producers in Kentucky and the nation.
Impacts
The overall objective of the University of Kentucky Sheep Unit is to develop and promote adoption of programs and procedures that will lead to a more economically viable sheep industry in Kentucky and the nation. This project provides an evaluation of a major hair breed of sheep. Upon its completion, it will answer the question of how the White Dorper, a hair sheep breed, will fit the modern meat industry and how large and small flocks can be used in mainstream sheep production systems. By project's end, lifetime ewe productivity data will have been collected on a minimum of 132 ewes differing in percentage White Dorpter breeding and over 200 wether lamb carcasses will have been evaluated for fatness, muscling, quality, and yield. Long-term efficacy of a management program for control of Haemonchus contortus in ewes will also have been evaluated. Accomplishment of project obectives will provide the sheep industry with a viable solution for improving economic efficiency
while maintaining product quality.
Publications
- Aaron, D. K., D. G. Ely, E. Fink, B. T. Burden, and M. M. Simpson. 2008. Carcass composition of Polypay versus White Dorper x Polypay Crossbred lambs (abstract) . J. Anim. Sci. (In Press).
- Simpson, M. M., D. K. Aaron, E. Fink, B. T. Burden, and D. G. Ely. 2008. Control of Haemonchus contortus infestation in ewes with copper sulfate (abstract). J. Anim. Sci. (in press).
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Progress 01/01/06 to 12/31/06
Outputs
Ewe reproductive performance and maternal performance through weaning was summarized for Polypay (PP) ewes producing PP and 1/2 White Dorper (WD) lambs (n = 81 and 75), 1/2 WD ewes producing 3/4 WD lambs (n = 96), and 3/4 WD ewes producing 7/8 WD lambs (n=34). Ewe Reproductive Performance. Ewe reproductive performance declined as percentage WD breeding increased beyond 50%. Pregnancy rates were lowest for 3/4 WD ewes (P < 0.05). These ewes were also the least prolific while PP ewes were the most prolific. However, PP ewes had the highest lamb loss rate (P < 0.05). It should be noted that results are confounded with a decrease in age and parity of the ewes. As percentage WD breeding increased, ewes were also younger. Decreased reproductive performance would not be unexpected with younger ewes having their first lambs, regardless of mating type. Ewe Maternal Performance. Total litter weaning weights, which are indicative of overall ewe productivity, were heaviest for PP
ewes producing 1/2 WD lambs and for 1/2 WD ewes producing 3/4 WD lambs. Litters produced by 3/4 WD ewes were lightest. PP ewes bred to PP rams weaned an average of 1.85 lambs, PP ewes bred to WD rams weaned 1.96 lambs, 1/2 WD ewes weaned 1.88 lambs and 3/4 WD ewes weaned 1.47 lambs. As percentage of WD breeding increased beyond 50%, overall productivity of ewes in the flock decreased. However, this decrease is partly due to the loss in both maternal and individual heterosis that occurs as grading up to WD breed continues. Differences in age and parity must also be considered. Higher percentage WD ewes may be earlier maturing than ewes of the foundation PP breed. At comparable ages and parities, however, they may be equally productive in a pasture system and they should not require shearing.
Impacts
Results obtained to date have been presented to sheep producers in Kentucky and Indiana and will help them make decisions relative to their sheep enterprises. AS more and more producers consider a change from traditional wool sheep produced under intensive conditions to hair sheep produced under low-input pasture systems, having information on reproductive and maternal performance of hair sheep ewes, such as the White Dorper, becomes increasingly important.
Publications
- Aaron, D. K., D. G. Ely, E. Fink, and R. A. Zinner. 2006. Ewe productivity in a grading-up mating scheme designed to remove wool from a traditional breed. J. Anim. Sci. 84 (Suppl. 2):25. Abstract #78.
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