173. G E N E T I C AND E N V I R O N M E N T A L E F F E C T S C O M P O S I T I O N OF l A M B S 0. A. ON FAT CRAHER Ebny people were informally asked if they l i k e d lamb and if not, why. The main objections voiced by people who do not l i k e lamb were that the odor of cooking lamb is undesirable and that they would taste t h e f a t f o r a long period of time after eating. &en people who do l i k e lamb admitted that the f a t tends t o coat the inside of the m u t h and leaves an undesirable after t a s t e. Eating quality of lamb was discussed with sheep carcass salesmen f o r the major packing companies and it was t h e i r opinion that t h e p a l a t a b i l i t y of lamb and mutton f a t is a major problem i n merchandizing. A survey of the literature substantiated these conjectures. The tallowy e f f e c t of mutton f a t is apparently due to the high degree of saturation of t h e f a t t y acids which increases the melting point. Mutton f a t contains a l a r g e r amount of s t e a r i c acid and l e s s o l e i c acid than beef tallow and lard. A greater degree of saturation i n mutton f a t is also indicated by iodine values of 3546 as compared t o iodine values f o r beef tallow and lard, respectively, of 4048 and 5377. The melting point of mutton f a t ranges f r o m 445loC, whereas, beef f a t melts f r o m 4048OC and lard melts from 3346OC. (AMIF, 1960). The above findings resulted i n a revision of t h e Colorado cont r i b u t i n g project t o W61 (Development of selection c r i t e r i a f o r the genetic ttmprovement of carcass merit i n sheep) t o research on lamb flavor and f a t composition. Elnvironmental e f f e c t s on f a t composition a r e being studied and fat samgles f r o m inbred l i n e s of sheep are being analyzed t o determine if enough genetic variation exists to make selection f o r a more desirable fat possible. While feeding d i f f e r e n t types and amounts of f a t t o sheep have l i t t l e e f f e c t on subcutaneous fat (Shorland, 1955) other environmental factors have rather profound effects. Callow (1958) has observed that such conditions a s temperature, rate of f a t deposition, l e v e l of fatness and stage of maturity can e f f e c t the iodine numbers of sheep f a t. P r e l i m i n a r y studies at the Colorado s t a t i o n indicate that alterat i o n of rumen fermentation patterns by feeding a n t i b i o t i c s w i l l change f a t composition. Shaw, e t al. (1960) reported that feeding steamed corn and pelleted hay increased iodine numbers of f a t f r o m Holstein s t e e r s. Feeding o r implanting stilbestrol also appears t o a l t e r t h e characteristics of depot f a t. The following presentation is a summary of t h e results obtained a t the Colorado s t a t i o n since t h e project revision i n 1960.
174. Tlie f i r s t problem encountered was s e l e c t i o n of a s i t e on t h e lamb carcass f o r collection of f a t samples. The area arcund tile dock i s a desirable location because c u t t i n g f a t o f f the dock does not damage t h e appearance of t h e carcass and it i s a r e l a t i v e l y convecient s i t e f o r biopsy. To determine t h e usefulness of sampling from a s i n g l e location, f a t was collected from e i g h t d i f f e r e n t areas of 82 lamb carcasses and analyzed f o r iodine numbers, saponification numbers and melting points. Freliminary r e s u l t s obtained froa 23 of t h e carcasses are l i s t e d i n Table 1. The differences i n composition of f a t between areas i s highly s i g n i f i c a n t. However, the correlations f o r iodine numbers between dock fat and t h e o t h e r seven areas are high enough t o sanple from t h e dock and p r e d i c t t h e composition of t h e o t h e r areas. Prediction of f a t composition from one area t o another i s possible because, although iodine nwo'oers d i f f e r, there i s a d e f i n i t e p a t t e r n i n all lambs with the perinephric f a t having the lowest and l e g f a t t h e highest iodine numbers. Table 1. Average values by area of carcafis and dock x o t h e r area c o r r e l a t i o n s of iodine numbers. Skponification Melting CorPelations Area Numbe r PcJint r dock 45.7 198.3 43.2 cod 43.6 198.2 45.1.81 kidney 37.4 196.6 48.5.75 1% 46.9 197.6 42.5.95 loin 43.4 198.5 4 90 neck 44.1 197.8 44.G 92 rzck 43.O 199.3 42.5.85 shoulder 44.4 190.7 42.9.90 average 43.6 198.0 43.9 In another study t e n lambs (Lot I) were fed outdoors i n the coldest part of the winter Eznd t e n lambs (Lot 11) were kept i n a heated room t o deteimiue the effect of ambient temperature on f a t composition. Onehalf of each group of lambs were shorn. As reported i n Table 2, f a t f r o m lambs kept w a r m had s i g n i f i c a n t l y lower iodl'ne numbers and higher melting points than t h e lambs kept outside (P<G.Cl). These results indicate tbat feeding lambs i n t h e winter i o cold c l i m t e s might produce a mre desirable product. Analysis of Fat from LarnXTed a t Temperature Extremes Saponification Melting Fo i n t Treatment 52.6 199.8 41.7 Lot 1 40.9 52.9 199.7 shorn 42.4 52.4 199.9 unshorn Table 2. Lot I1 shorn unshorn 46.9 48.4 45.4 199.8 199.6 zoo. 0 44.0 43.0 45.0
175. The e f f e c t s of p e l l e t i n g feed and feeding an a n t i b i o t i c on f a t composition were studied using 40 lambs i n a 2 x 2 f a c t o r i a l design. There were no s i g n i f i c a n t differences i n any of the c h a r a c t e r i s t i c s of t h e f a t between the p e l l e t e d and unpelleted feed treatments. The a n t i b i o t i c used was zinc b a c i t r a c i n added t o the feed a t such a r a t e t h a t approximately 40 mg. were consumed d a i l y per head. The melting points of f a t from lambs supplemented with b a c i t r a c i n were not s i g n i f i c a n t l y d i f f e r e n t from the f a t from the untreated lambs, but t h e iodine numbers were s i g n i f i c a n t l y higher (P< 0.C1) Apparently, a l t e r a t i o n s took place i n t h e m n which suppressed hydrogenation of u n d t u r a t e d f a t t y acids. The r e s u l t s of t h i s study a r e reported i n Tables 3 and 4. The treatments by l o t are a8 follows: Lot I p e l l e t e d feed with bacitracin, Lot I1 pelleted feed without bacitracin, Lot I11 mal with bacitracin, and Lot IV meal without bacitracin. bt I l t i n g Points Melting Point, OC. 4 48.4* ht I1 46.6 42.0 bt 111 47.4+ 42.3 45.5 43.1 Lot N *Lots I & I11 s i g n i f i c a n t l y higher than Lots I1 and IV, (P<O.Ol) There a r e no s i g n i f i c a n t differences between treatments f o r the various f a t t y a c i d percentages l i s t e d i n Table 4, although b a c i t r a c i n supplementation resulted i n higher iodine numbem. Apparently the slight increase i n most of the unsaturated f a t t y acids and decrease i n t h e various saturated f a t t y acids was a u f f i c i e n t t o produce s f g n i f i c a n t differences in iodine numbers, Table 4. Average Percentages Acids by carbon chain length and number of double bonds Lot I < 12 3.2 12 4.9 14 14"l 15 0.8 AB 23.6 16 16=1 0.5 Ea 2.7 17 C" 1.6 12.5 18 35.0 18l 4.9 18'2 18'3 1.2 0.o cjf Fatty Acids i n Lamb Fat Lot I1 3.9 2.8 5.5 25.0 5.6 2.6 11.7 31.4 47.5 Lot I11 2.7 5.o 1.7 1.1 24.6 5.3 3.2 1.7 11.7 35.0 4.6 1.4 Lot Iv 3.O 1.5 1.2 0.6 24.0 4.4 2.6 2.4 1.4 13.8 34.9 4.5 1.8 3.8 t k a t u r a t ion 49.7 50.2 47.7 W e s e acids have not y e t been i d e n t i f i e d and have a r b i t r a r i l y been assigned these designations.
176. Fat samples were collected f m m around the dock o f 165 r a m lamb carcasses from the U. S. Sheep Experiment Station a t k b o i s, Idaho t o a t tempt t o determine s i r e differences i n f a t composition. The l a b s were progeny f r o m inbred ram top cross matings and represent three breeds on the sire side and two years' data. The progeny were f r o m a t o t a l of 79 ram w i t h d i f f e r e n t ram each year. Although the numbers of progeny f r o m each ram were l i m i t e d (range of one t o f i v e ) t h e t e n t a t i v e r e s u l t s were quite i n t e r e s t i n g. The data a r e not completely analyzed a t t h i s t i m, but a preliminary analysis of variance revealed highly s i g n i f i c a n t differences between s i r e s f o r iodine numbers of progeny fa,t and a h e r i t a b i l i t y estimate f o r iodine number of 1.5. Rernoval of t h e year and breed e f f e c t will pmbably lower t h e h e r i t a b i l i t y estimate t o a more r e a l i s t i c figure. Average iodine values by sire ranged from a low of 41.6 t o a high of 5 2. 8 which is a great deal of variation f o r a n i m l s reared under t h e sane environmental conditions. There was also considerable variation i n t h e melting points of t h e which suggests the possif a t by s i r e. The overall range was 39.6 t o 46.4'C b i l i t y of improvement of lamb f a t p a l a t a b i l i t y through selection. Samples of f a t have been obtained from over 206 lamb carcasses of known genetic background through the cooperation o f New Yixico State Univ e r s i t y t o further explore t h e h e r i t a b i l i t y of f a t composition. The lambs were from t h e various l i n e s of sheep a t t h e U. S. Sheep Experiment Station a t Fort Wingate, New Mexico and were processed through the New Elexico State University Meats Laboratories. If t l e genetic variation i n f a t com2osition f y o m the Fort Wingate sheep substantiates tht found i n the Dubois sheep a breeding flock will be established a t the Colorado Agricultural Fxperiment Station and the selection program w i l l be based on f a t composition. Lamb f l a v o r studies being conducted a t the Colorado Station a r e not reported i n t h i s paper but will be i n c o q o r a t e d i n t o t h e selection index i f a breeding flock is s e t up a t t h e Station livestock farm. LITEZATURE CITED American Meat I n s t i t u t e Foundation. 1960. The science of meat and meat products. W. H. Freeman and Company, San Francisco. Callow, E. E. 1958. Comparative s t u d i e s of meat. Part V I. Factors a f f e c t i n g the iodine number of f a t f r o m the f a t t y and muscular t i s s u e s of lambs. J. Agr. S c i. 51:361. Shaw, J. C., W. L. Ensor, H. F. Tellechea and S. D. Lee. 1960. Relationship of d i e t t o rumen v o l a t i l e f a t t y acids, d i g e s t i b i l i t y, efficiency of gain and degree of unsaturation of body f a t i n s t e e r s. J. Nutr. 71:203. Shorland, F. B. 1955. Effect of the rumen on d i e t a r y f a t. Mature 1759129.
177. DR. WALTERS: Thank you, Dave, f o r a most i n t e r e s t i n g report, undoubtedly the forerunner of some mrk t h a t w e t 1 1 hear more and more about as time goes on. No doubt t h i s r e p r t has s t i w l a t e d a great deal of curiosity, and will you Please make note of t h e questions which come t o your minds? We hope w e ' l l have s u f f i c i e n t time f o r questions and discussion after all t h e speakers have given t h e i r reports, The next speaker on our program, I believe, is with us for the first time t h i s year. It came t o the a t t e n t i o n of t h e committee t h a t a t the University of California, a great d e a l of work has been done i n t h e area of biopsy technics, p a r t i c u l a r l y with reference t o mrk with lambs. Our first contaci; with Professor Spurlock indicated that he wasn't sure &.ether o r no% he'd be able t o attend t h i s meeting. Later on it developed t h a t circume are very g r a t e f u l f o r your stances were suck t h a t he could be with us. W coming t h i s distance, Dr. Spurlock, t o give us your very i n t e r e s t i n g peport on "The Biopsy Technique f o r Estimation of Meat Quality i n LEun13s." Prof e s s o r Spurlock f r o m California. ######Pi#####