Early weaning of lambs from ewes on native pasture offers several advantages to the range operator. Increased base ewe flock numbers and/or less grazing pressure, better range management, less carcass damage from needles and better feed efficiency of a younger lamb in drylot are some of the advantages that can be listed for early weaning.                                   A study was initiated at the Antelope Range Field Station in 1971 to study alternative management systems for range lamb production

Slyter, A. L.

Trevillyan, W. R.

English

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South Dakota State UniversityOpen PRAIRIE: Open Public Research Access InstitutionalRepository and Information ExchangeSouth Dakota Sheep Field Day Research Reports,1973 Animal Science Reports1973Weaning Systems for Range Lambs: A ProgressReportA. L. SlyterSouth Dakota State UniversityW. R. TrevillyanFollow this and additional works at: http://openprairie.sdstate.edu/sd_sheepday_1973This Report is brought to you for free and open access by the Animal Science Reports at Open PRAIRIE: Open Public Research Access InstitutionalRepository and Information Exchange. It has been accepted for inclusion in South Dakota Sheep Field Day Research Reports, 1973 by an authorizedadministrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For more information, pleasecontact michael.biondo@sdstate.edu.Recommended CitationSlyter, A. L. and Trevillyan, W. R., "Weaning Systems for Range Lambs: A Progress Report" (1973). South Dakota Sheep Field DayResearch Reports, 1973 . Paper 6.http://openprairie.sdstate.edu/sd_sheepday_1973/6• · .  • -· • South Dakota State University Brookings , South Dakota Department of Animal Science Agricultural . Experiment Station Weaninc:r· ·· Systems for Range Lambs A Pl"ogress Report . A .  L .  Slyter and W .  R .  Trevillyan A .  S .  Series .7 3  ... 5 Early weaning of lambs from ewes on native pasture offers several advantages to the range operator . Increased base ewe flock numbers and/or less grazing pressure , b etter range management , less carcass damage from needles and better feed efficiency of a younger · lamb in drylot are some of the advantages that can be lis ted for early weaning . A study was initiated at the Antelope Range Field Station in 1971 to study alternativ� · management systems for range lamb production . Experimental Procedure Trial 1 - 1971 One · hundr�d twe�ty-five straightbred Targhee . and Suffolk-Targhee crossbred wether lambs were assigned at random within breed� of · s ire and type .of b irth groups . to one ·of three management systems on May 2 4 , 1971 , at approximately :80 days, of "' . age . In the control system , nat ive range pasture , the lambs were allowed to run with the ir dams grazing on native range at the Antelope Range Field Station unti l  s laughter . Lambs in the drylot fin ishing system were sorted from the ir dams , trucked 70 miles and placed on feed in a drylot at the Newell Field Stat ion . In the remaining · system , sudan sorghum pasture , the lambs grazed with their darns on native range until July 5 when they were weaned. and placed on temporary sudan sorghum pasture . · The drylot ration� was compos ed of 60% cracked: corn and 40% ground alfalfa hay . All lambs were ' provided a trace minerali zed salt and ' dicalcium phosphate mix in equal parts free choice and wormed as necessary . Lambs in drylot consumed an average of 2 .  7 pounds of feed per head daily . Eight and .one-half acres :: · of sudan sorghum were grazed from July 5 to August 2 3  ( 49 days ) as the feed sourc.e . for the temporary pasture group of lambs . A hail storm in July greatly reduced the . . . sorghum forage ; However , sufficient forage appeared avai lable unti l  termination of the feeding period . Lambs on the native pasture had unlimited acreage to graze . Trial 2 - 19 72 Treatments employed in trial 2 were similar to thos e used in trial 1 with the following exc eptions . Lambs were assigned to their respect ive treatments June 13 and the pasture groups were sold August 6 .  The drylot lambs were trucked to Brookings for feeding . They were self-fed a pelleted ration that averaged 50% alfalfa and 50% cracked corn containing 5 mg . aureomycin per pound . Average drylot feed consumption was 3.9 pounds per head dai ly . The starting date on sorghum for the sudan sorghum pasture system was July 3 .  Final weights were taken on August 5 for the pasture groups and August 7 for the drylot lambs . 2 5  - 2 -All pas ture lambs we ighing 9 0  pounds or more were trucked from Antelope Range to Sioux Falls for slaught�r and collection of carcas s  dat a . No lambs weighing les s than 90 pounds at slaughter time were included in the 197 2  carcass data . A ll drylot lambs remained on feed after the August 7 weights were taken and were slaughtered at the Univers ity Meats Laboratory from August 18 to 24 . All lambs were vaccinated for enterotoxemia at the start of the feeding period and wormed as necessary . Lambs in the drylot group were shorn on arrival at the feedlot . · Results Trial 1 The results of thi s  trial are summari zed in table 1 .  Average daily gain and total gain were higher for lambs grazing sudan sorghum pasture than for other treatments . Dress ing percent was 3 . 6% higher for the drylotted lambs than for either pasture system . As a result , little difference was observed in pounds of carcass produced . Final .live weights for the pasture groups were taken wi thin 4 hours after removal from feed and water , while the drylot lambs were withdrawn approximately 12 hours befo;e weighing . Therefore , weight gains tend to be higher and dress ing percent lower for pas ture lambs as a result of the weighing procedure . It  would appear that carcass weight would be a more accurate end point measurement of treatment effects on performance . Only small differences �ere observed in the carcass traits evaluated . Quality • . ·  grades were lower in all groups than desired as· a result of underfinished carcass es . • Lambs on native pa�ture graded .one-third of a · grade lower than e ither of the other two groups . Trial 2 Results of trial 2 are shown in table 2 .  Lambs on sudan sorghum pasture or fed in drylot made the most rapid.gains . Average daily gains in all groups were superior to thos e ob s erved in trial l �· A higher percentage of the drylot fed lamb s had reached market weight ( 90 pounds or more ) by August 5 than either of the other two groups . Only 67 . 6% of .the l.ambs . on n a:t.ive range weighed 90 pounds or more when final weights were taken . Due .. to market pressure , no lambs we ighing les s  than 90 pounds were s laughtered in 19 72 ·and therefore are not included in the carcass data reported .  Thi s  would tend to b ias the carcass. data since only the heavier lambs from each group wer.e slaughtered . Carcass weight , dress ing percent and quality grades were higher for the drylot sys tem than for either pasture system . Cons iderable carcass damage from "needles " was obs erved in those lambs off of the native pasture system . Drylot fed lambs carried more fat and therefore had a higher numeri cal yield grade score . Add it ional data are currently being collected on this study . 26 • ·-• • • - 3 -Table l .  Effect of Management Sys tems .on Performance and Carcass Tra its for Growing and Finishing Spring Larnbsa . - -1971 · · · Treatment Number of lambs Initial weight , 5- 21- 71 , lb .  Final weight , 8- 23-71 , lb . b Total gain , lb . Average daily gain . lb .  Carcass weight , lb . • Dress ing percent Quali ty gradec Leg conformationc Yield graded Number of deaths a All are wether lamb s . Dry lot 42 5 5 . 4  86 . 8.  31 . 3  0 . 34 41 . 2  46 . 7  8 . 7  9 . 3 3 . 2  1 Sudan Native sorghum range pasture pa�ture 3 8  3 9  5 1 . 8  54 . 2  100 . 1  94 . 7  . 48 . 3  40 . 5  0 . 5 3 0 . 4 5  4 3 . 6  41 . 2  43 . l  43 . l  8 . 6  7 . 7 9 . 5  8 . 9  3 . 1  2 . 8  2 3 b Final weights were taken with lambs off feed and water 2 to 4 hours in all groups except -.the'� :-drylot whi ch ·i.;ere · off feed and water. overnight . c Low · good :r:e'. :7 ,  average good ::: · g ;  · high good = 9 .  . -. . d Yield grades · jl · to . 6, ·calculated on the basis of the federal grader ' s  estimate of leg conformation�, fat thi ckness and percent ·kidney . Yield grade 1 ,  most desirable . Tab le 2 .  Effect of Management Systems on Performance and Carcass Traits for Growing and Fini shing Spring Larnbsa - 1972 Treatment Number of lambs Initial weight , 6-13-72 , Final weight , 8- 5 - 7 2 , lb . Total gain , lb . Average daily gain , · lb. Percent �ambs �� i�hing pounds · ·or·· · mo�e-• • r . . . Live we ight ' df . lambs slaughtered � lb .  Carcas s we ight , lb .  Dress ing percent Quality .. ·grp._deb Leg conformationb Yield gradec Number of deaths 9 0  lb . a All are wether lambs . Sudan sorghum Dry lot pasture 29 38 70 . 1  70 . 2  102 . 9  102 . 9  3 2  . • 8 32 . 7  0 . 6 2 ' 0 . 62 90 . O" 84 . 2  10 8 . 0  107 . 0  55 . 0  48 . 8  50 . 9  4 5 . 6  11 . 2' 10 . 0  11 . 1  11 . l  3 . 7  2 � 3  0 0 b LOT good = 7 '  average .. good = 8 '  through h1gh choice = 12 • ·Nat ive range pasture 39 69 . 7  9 7 . 6 . 2 7 . 9  0 . 5 3 67 . 6  1 0 3 . 8  47 . 7  46 . 0  10 . 0  10 . 2  2 . ·2 0 c Yield grades l to 6 c�lculated on the basis of the federal grader ' s  estimate of leg conformation , fat thickness and percent kidney . Yield grade 1 ,  most des irable . 2 7  . . 

Weaning Systems for Range Lambs: A Progress Report

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Weaning Systems for Range Lambs: A Progress Report

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