BORDER LEICESTER AND FINNSHEEP CROSSES. I. SURVIVAL, GROWTH AND CARCASS TRAITS OF FI LAMBS 1

BORDER LEICESTER AND FINNSHEEP CROSSES. I. SURVIVAL, GROWTH AND CARCASS TRAITS OF FI LAMBS 1 A. F. Magid 2, V. B. Swanson 2, J. S. Brinks 2, G. E. Dickerson 3 and G. M. Smith 4 Colorado State University, Fort Collins 8523, and US Department of Agriculture, Clay Center, NE 68933 Summary Data on 639 lambs were collected at the Roman L. Hruska US Meat Animal Research Center, Clay Center, Nebraska, in 1973 and 1974 and used to compare the Border Leicester (BL) and the Finnsheep (Finn) as sire breeds. Traits studied were preweaning survival rate, preweaning and postweaning growth rates and carcass traits. BL-sired lambs were.3 kg heavier at birth, 12% higher in mortality to weaning at 8 weeks and 16 g/day slower in preweaning gain, but were not significantly lighter at weaning or in adjusted 7-day weight. Sire breed had no average effect on postweaning gains or weights, but there was a significant change in the final and 22-week weights of Finn-sired versus BL-sired lambs from inferiority in 1973 to superiority in 1974. This reversal in the sire breed differences between years could reflect the change in the genetic sample of sires used in the 2 years. It also may indicate a poorer adaptability of BL-sired lambs born in 1974 to the 22% faster preweaning and 25% slower postweaning gain for 1974 versus 1973. BL-sired ram lambs had.6 cm more rib fat,.23 cm more body wall thickness, higher quality and maturity grades but less internal fat than did Finn-sired lambs, and equal yield grades and boneless or trimmed cut yields. ;Published as Paper No. 252, Journal Ser., Colorado Exp. Sta., Fort Collins. Partial publication of senior author's thesis research. Present address: Univ. of A1 Fateh, Tripoli, Libya. 2Graduate student, associate professor and professor, respectively, Dept. of Anita. Sci., Colorado State Univ., Fort Collins 8523. 3 Roman L. Hruska US Meat Animal Research Center, SEA, USDA, Clay Center, NE 68933. 4 Dept. of Anim. Sci., Texas A&M Univ., College Station 77843. (Key Words: Finnsheep, Border Leicester, Crossbreeding, Lamb Performance.) Introduction The performance characteristics of Finnsheep (Finn) have been reported by Maijala (1966), Donald and Read (1967), Donald et al. (1968), Bradford (1972), Laster et al. (1972), Dickerson and Laster (1975), Dickerson (1974, 1977) and Nitter (1975). Comparisons of Finn crosses with domestic breed crosses for lamb survival and for preweaning and postweaning growth were reported by Dickerson et al. (1975) and Dickerson (1977). Boylan et al. (1976) and Dickerson (1977) reported that carcasses of 89 Finn crossbred lambs had more internal fat and poorer conformation than most domestic breed crosses, but that they had comparable yields of boneless cuts and were commercially acceptable. Border Leicester (BL) sheep have not been utilied extensively in the United States. However, they are used extensively in other countries (Pattie and Smith, 1964; Donald et al., 1968; Hight and Jury, 197, 1971; Hight et al., 1976). In the United States, Light et al. (197) and Failer (1975) have shown that BL-sired ewes wean in excess of 18% lamb crop, are excellent milkers with good dispositions and shear heavy fleeces (5 to 6 kg) of medium-1ng staple wool. An experimental evaluation of BL for use in crossbred market lamb production was initiated in 1973, with Finn crosses used as controls. Preweaning livability, preweaning and postweaning growth rates and carcass traits of BL- and Finn-sired lambs are reported in this paper. Production and maternal performance of these crosses and the carcass merit of their lambs are reported in the two ensuing articles (Magid et al., 1981a, b). 1253 JOURNAL OF ANIMAL SCIENCE, Vol. 52, No. 6, 1981

1254 MAGID ET AL. Materials and Methods Experimental Procedure. The data reported were collected at the Roman L. Hruska US Meat Animal Research Center, Clay Center, Nebraska, on lambs born in 1973 and 1974 as a part of the Germ Plasm Evaluation Program. Phase I of the experiment involved the production of Finn- and BL-sired lambs. The distribution of lambs by breed of sire, breed of dam and year of birth is presented in table 1. In the 1972 breeding season, from November 1 to December 5, 11 Finn and six BL rams were used in single-sire pen matings. In the 1973 breeding season, from December 11 to January 21, four of the BL rams from the 1972 breeding season and three repeated Finns and one new Finn ram were used in multiple-sire matings. The BL rams were purchased in October 1972, five from the Olson flock, Dawson, Minnesota, and one from the Miller flock, Durbin, North Dakota. The Finn rams were descendants of the Finn sheep imported in 1968 and 1969 and produced at the Center (Dickerson et al., 1975). During gestation, ewes were on pasture but received supplemental alfalfa hay. Thirty days before lambing, supplemental feed was changed to include.5 kg grain/head daily. One week before lambing began, ewes were confined in drylot and fed corn silage ad libitum. Immediately after lambing, ewes and lambs were moved from the larger lambing pens into 1.2 x TABLE 1. DISTRIBUTION OF LAMBS BORN, BY SIRE BREED, DAM BREED AND YEAR Breed of No. Sire Dam 1973 1974 Total BL Finn Total Hampshire 34 33 67 Rambouillet a 25 42 67 Targhee 2 25 45 ~-Finnsheep b 59 55 114 Hampshire 45 38 83 Rambouillet a 37 43 8 Targhee 27 22 49 ~-Finnsheep b 87 47 134 334 35 639 aincluded five unregistered Fine Wool and Rambouillet Fine Wool crosses. b89 group included crosses of Finnsheep with Hampshire, Suffolk Rambouillet, Polled Dorset, Targhee, Corriedale, Coarse Wool, Fine Wool and Navajo breeds. 1.5 m pens equipped with a heat lamp for a 24- to 48-hr period. A few weak lambs and those in excess of two per ewe were removed from the ewe at 1 to 2 days of age and placed in an artifical rearing unit as described by Glimp (1972). About 2 days after lambing, ewes chat lambed on the same days were grouped, along with their lambs, in larger pens and fed corn silage to weaning. All lambs were weighed at birth and scored for vigor (see footnote to table 3). Survival of lambs from birth to weaning was scored as or 1. Lambs in each pen were weaned when the youngest animals in the pen reached 5 week of age. After weaning, ram and ewe lambs were separated and placed on a self-fed growing diet in dry lots to about 22 weeks of age. The lamb growing diet is described in table 2. The 7-day weight was calculated as (prewear, ing average daily gain x 7) + lamb's birth weight. Final weights were adjusted to 22 weeks of age as follows: (postweaning average daily gain days from weaning to 154 days) + actual weaning weight. In 1974, all ram lambs produced as part of Phase I were slaughtered in two groups (November 22, 1974, and January 6, 1975) at approximately 45 kilograms. Carcass trait data and postweaning nutrition and management procedures were as described by Olson et al. (1976). Statistical Procedures. All traits were analyed by least squares as described by Harvey (1975). The model for birth traits included the fixed effects of year, sex, type of birth, age of dam, sire breed, dam breed and the two-way interaction of sire breed dam breed. Birth date was included as a continuous variable in the analysis of birth and weaning traits. The statistical model used for the analysis of weaning traits was the same as that used for the birth traits analysis, except that it included type of birth and rearing instead of type of birth alone. Birth-rearing classes were coded as described by Dickerson et al. (1975) and Olson et al. (1976) (see footnotes to table 3). The statistical model used for the analysis of postweaning traits included the fixed effects of year, type of birth-rearing, sex, age of dam, sire breed, dam breed and year sire breed, year x dam breed and sire breed x dam breed interactions. Birth date was included as a continuous variable. Because numbers were considerably smaller for postweaning than for preweaning traits, type of birth-rearing was coded simply as

PERFORMANCE OF LEICESTER- AND FINN-CROSS LAMBS 1255 TABLE 2. LAMB GROWING DIET (1973 AND 1974) Ingredient % Nutrient composition % Corn (IFN 4-2-935) Soybean meal (44% CP) (IFN 5-4-64) Alfalfa (dehydrated 17% CP) (IFN 1-O-23) Molasses (with 3% binder) (IFN 4-4-696) Limestone Salt, trace minerals a Vitamine premix b Durabond Ammonium chloride Chlorotetracycline (11 g/kg) 53.75 18. 2. 4.45.1.4.1 2.5.75.4 Protein 16.76 Ca.41 P.34 Dig. energy 3.2 (Mcal/kg) asalt with trace mineral and organic I in 1973 and 1974. bvitamin premix contained per kilogram: 8.8 million IU vitamin A, 88, IU vitamin D and 88 IU vitamin E. single born and reared versus all multiple born or reared. The statistical model used in the analysis of carcass traits (1974) included the fixed effects of sire breed, dam breed, sire breed dam breed interaction and slaughter date. A preliminary analysis was conducted to test for all possible two-way interactions between effects included in the analysis of all traits. The analysis indicated that the only significant interactions were sire breed dam breed for birth weight and sire x year for final feedlot weight. Birth-rearing class, age of dam and birth date had no effect on the carcass traits; hence, these effects were omitted from the final analysis. Results and Discussion Birth and Weaning Traits. Birth year, type of birth, birth date and sex of lambs all had significant influences on birth weight and weaning traits (table 3). Only type of birth influenced lamb survival to weaning, and none of the environmental factors significantly affected lamb vigor at birth. Age of ewe had a significant effect only on birth weight. Lambs born as triplets or twins had lower birth weights (-1.7 and -.9 kg) and poorer livability (-38 and -16%) than lambs born as singles. Lambs born and reared as singles weighed more at weaning (3.6 kg) and 7 days (4.1 kg) and gained faster to weaning (47 g/day) than lambs in multiple type birth-rearing classifications. Ram lambs significantly exceeded ewe lambs in birth weight (.2 kg), weaning weight (.9 kg) and 7-day weight (1.2 kg) but had slightly poorer survival (-6%) to weaning. Birth weight increased significantly with age of dam, and lambs from 3- and 4-year-old ewes tended to have higher survival to weaning, faster gains to weaning and higher 7-day weights than lambs from 2-year-old ewes and ewes 5 years old or more, but these latter differences were not significant. The significant partial linear regressions on birth date, although small, indicate that lambs born later in the season were heavier at birth but gained more slowly to weaning than did lambs born earlier. Sire breed had a significant effect only on birth weight, lamb survival to weaning and preweaning daily gain (table 4). BL-sired lambs were slightly heavier (.3 kg) than Finn-sired lambs at birth, but they had 12% poorer survival to weaning and gained 8% more slowly and were not significantly lighter at weaning and 7 days of age. Dickerson et al (1975) reported that Finn crosses were superior to Rambouillet crosses in survival (81 vs 61%), preweaning gain and 1-week weight, but had lighter birth weights. In that study, only the Suffolk-sired crosses significantly surpassed Finn crosses in lo-week weight. Ewe breed effects were not statistically significant for any preweaning trait studied, except birth weight (P.1). Lambs from Hampshire ewes were heaviest at birth (4.1 kg), and lambs from the 89 and Rambouillet ewes were lightest (3.6, 3.7 kg). Survival, as adjusted for type of birth-rearing, was highest for lambs of 89 ewes (67%), followed by those of

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1258 MAGID ET AL. Rambouillet (62%), Targhee (58%) and Hampshire (54%) ewes. Lambs from Targhee ewes were the heaviest at weaning and 7 days, followed by lambs of Rambouillet, Hampshire and 89 ewes. Although not significant, these results are in general agreement with those of Dickerson et al. (1975), who reported nonsignificant differences among domestic ewe breeds in survival of their crossbred lambs and highly significant ewe-breed effects on lamb birth weight and preweaning gain. Postweaning Traits. Sex, type of rearing and birth date had important influences (P.1) on final weight (FW) and adjusted 22-week weight (W22), but only year and sex effects were important for postweaning daily gain (DG; table 5). The year x sire breed interaction was significant for FW and W22 but not for DG. Sire breed had no significant effect on any of the postweaning traits studied (table 5). However, there was a significant reversal between years in the sire breed difference in FW and W22. This may reflect genetic changes in the samples of sires between years or it may indicate poorer adaptability of BL-sired lambs in 1974, when preweaning gains were 122% and postweaning gains were only 75% of the means for 1973. Dam breed had a highly significant effect on FW, but not on DG or W22 ; lambs from Targhee and Hampshire ewes had a higher FW than lambs from Rambouillet and 89 ewes. Dickerson (1977) reported that Finn-sired crossbred lambs were much lighter at birth than Rambouillet cross and purebred lambs, but that they equaled or exceeded other lambs in weights at 1 through 22 weeks of age and then grew more slowly after 22 weeks. In TABLE 5. LEAST-SQUARESMEANS AND ERROR STANDARD DEVIATIONS FOR POSTWEANING DAILY GAIN (DG), FINAL WEIGHT (FW) AND 22-WEEK WEIGHT (W22) Factor No. a DG, g FW, kg W22, kg # 35 (329) 17 38.7 33.2 Year *** * 1973 187 (166) 195 4. 33.8 1874 162 (163) 146 37.4 32.6 Type rearing *** *** Single 133 (128) 169 4.3 35.3 Multiple 217 (21) 172 37.1 31.1 Sex *** *** *** Male 171 (162) 181 4.4 34.4 Female 179 (167) 159 36.9 32. 1973 *** Finn sire 112 (99) 191 38.7 33.8 BL sire 75 (67) 199 41.2 33.9 1974 *** * Finn sire 96 (96) 15 38.9 33.9 BL sire 67 (67) 141 35.8 31.2 Dam breed ** Hampshire dams 76 (76) 178 4.4 33.8 Rambouillet dams 58 (49) 163 37.4 32.4 Targhee dams 5 (48) 175 4.3 34.5 ta-finn darns 166 (156) 164 36.6 32.2 b (on birth date) -.567 -.37 -.147 Error standard deviation 33 (39) df 4.3 6.3 5.58 anumbers in parentheses are for W2. *P.5. **P.1. ***P.O1.

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126 MAGID ET AL. the present experiment, lambs from 89 ewes sired by Finn rams would have been expected to show less growth heterosis than lambs from the other three ewe breeds. Carcass Traits. The effect of sire breed (table 6) was significant for carcass quality grade, maturity score, body wall thickness and kidney fat and was.highly significant for 12th rib fat. Carcasses of BL-sired ram lambs had.6 cm more rib fat,.23 cm thicker body wall and slightly higher quality grade and maturity scores, but.4% less kidney fat and similar yield grade and boneless or trimmed cut yields relative to carcasses of Finn-sired lambs. Dam breed effects were significant for quality grade, leg conformation score, 12th rib fat, body wall thickness, flank firmness score and dressing percentage. Ram lambs from Hampshire ewes ranked highest in all carcass grades and in external fat, but lambs from Targhee ewes were highest in dressing percentage (54.5%). Carcasses of Iambs from 89 and Targhee ewes were similar, with less external fat and poorer conformation than, but comparable cutability to, carcasses of lambs from Hampshire and Rambouillet ewes. These results agree to some extent with those of Boylan et al. (1976) and Dickerson (1977). These authors reported that carcasses of Finn-cross lambs were slightly inferior in conformation to carcasses of domestic breed crosses in most cases, but were comparable in cutability and were commercially acceptable. Discussion This study showed no sire breed differences between BL- and Finn-sired lambs in weaning weight and 22-week weight. BL-sired lambs were heavier at birth but poorer in both survival and preweaning growth rate and similar in postweaning growth rate. In terms of carcass merit, BL-sired ram lambs were slightly superior in quality, maturity and dressing percentage associated with more external fat, but were not superior in yield grade and boneless or trimmed cut yields. These results for lamb performance of 89 and 89 crosses under semi-intensive management conditions need to be combined with those for ewe performance of these crosses to assess the relative merits of BL and Finn breeds in crossbred lamb production. Literature Cited Boylan, W. J., Y. M. Berger and C. E. Allen. 1976. Carcass merit of Finnsheep crossbred lambs. J. Anim. Sci. 42:1413. Bradford, G, E. 1972. Genetic control of litter sie in sheep. J. Reprod. Fertil. (Suppl.) 15:23. Dickerson, G. E. 1974. Crossbreeding performance of Finn and domestic (U.S.) breeds of sheep. Proc. Working Symp. on Breed Evaluation and Crossbreeding Experiments, European Assoc. Anim. Prod., eist, Netherlands, September 15-2, 1974. Dickerson, G. E. 1977, Crossbreeding evaluation of Finnsheep and some U.S. breeds for market lamb production. North Central Region Pub. No. 246, USDA and Univ. of Nebraska, Lincoln. Dickerson, G. E., H. A. Glimp and K. E. Gregory. 1975. Genetic resources for efficient meat production in sheep: Preweaning viability and growth of Finnsheep and domestic crossbred lambs. J. Anim. Sci. 41:43. Dickerson, G. E. and D. B. Laster. 1975. Breed, heterosis and environmental influences on growth and puberty in ewe lambs. J. Anim. Sci. 39:94. Donald, H. P. and J. L. Read. 1967. performance of Finnish Landrace sheep in Britain. Anim. Prod. 9:47. Donald, H. P., J. L. Read and W. S. Russell. 1968. A comparative trial of crossbred ewes by Finnish Landrace and other sires. Anita. Prod. 1:413. Failer, Timothy C. 1975. Selected breeds and crosses of sheep. M.S. Thesis. North Dakota State Univ., Fargo. Glimp, H. A. 1972. Effect of diet composition on performance of lambs reared from birth on milk replacer. J. Anim. Sci. 34:185. Harvey, W. R. 1975. Least-squares analysis of data with unequal subclass numbers. USDA, ARS H-4. Hight, G. K., J. J. Atkinson, R.M.W. Summer and M. L. Bigham. 1976. Hill Country Sheep Production. VII. Wool traits of Romney and Border Leicester Romney ewes. New ealand J. Agr. Res. 19:197. Hight, G. K. and K. E. Jury. 197. Hill Country sheep production. I. The influence of age, flock and year on some components of reproduction rate in Romney and Border Leicester X Romney ewes. New ealand J. Agr. Res. 13:641. Hight, G. K. and K. E. Jury. 1971. Hill Country sheep production. III. Sources of variation in Romney and Border Leicester Romney lambs and hoggets. New ealand J. Agr. Res. 14:669. Luster, D. B., H. A. Glimp and G. E. Dickerson. 1972. Factors affecting reproduction of ewe lambs. J. Anita. Sci. 35:79. Light, Merle R., B. L. Johnson and Timothy Failer. 197. Productivity of selected breeds and crosses of sheep. 1. Experimental ewes. Farm Research. North Dakota Agr. Exp. Sta. 28, 71:26. Magid, A. F., V. B. Swanson, J. S. Brinks, G. E. Dickerson and G. W. Smith. 1981a. Border Leicester and Finnsheep crosses. II. Productivity of F 1 ewes. J. Anim. Sci. 52:1262. Magid, A. F., V. B. Swanson, J. S. Brinks, G. E. Dickerson and G. W. Smith. 1981b. Border Leicester and Finnsheep crosses. III. Market lamb production from crossbred ewes. J. Anita. Sci. 52:1272. Maijala, K. 1966. Causes of variation in litter sie of

PERFORMANCE OF LEICESTER-AND FINN-CROSS LAMBS 1261 Finnsheep ewes. 9th Internat'l Congr. Anim. Prod., Edinburgh (Abstr. 29). Nitter, G. 1975. Results of a crossbreeding experiment with sheep for different systems of fat lamb production. Livestock Prod. Sci. 2:167. Olson, Larry W., G. E. Dickerson and H. A. Glimp. 1976. Selection criteria for intensive market lamb production: Growth traits. J. Anita. Sci. 43:78. Pattie, W. A. and M. D. Smith. 1964. A comparison of the production of F 1 and F 2 Border Leicester Merino ewes. Australian J. Exp. Agr. Anita. Hus. 4:8.