Sheep & Goat Research Journal. Volume 29, 2014

Contents

High Frequencies of the αS1-Casein Zero Variant in Milk from Swedish Dairy Goats
Author: M. Johansson, M. Högberg and A. Andrén

Effects of Sex, Breed, Callipyge Phenotype, and Docked Tail Length on Rectal Prolapse in Lambs
Author: B. Zanolini, A.M. Oberbauer, S.D. Prien, M.L. Galyean and S.P. Jackson

Performance by Yearling Katahdin Ewes Grazing Toxic Tall Fescue Using Either Continuous or Rotational Grazing Schemes in Late Spring Through Summer
Author: E.A. Backes, J.D. Caldwell, B.C. Shanks, K.R. Ness, A.N.V. Stewart, L.S. Wilbers, C.A. Clifford-Rathert, A.K. Busalacki, H.A. Swartz, D.L. Kreider, and M.L. Looper

Effects of Diet Particle Size and Lasalocid on Growth, Carcass Traits, and N balance in Feedlot Lambs
Author: A.R. Crane, R.R. Redden, P.B. Berg and C.S. Schauer

Consumer Evaluation and Shear Force of Retail Domestic Grain-Finished, Imported New Zealand Grass-Finished, and Missouri-Produced Grass-Finished Lamb Racks
Author: K.L. Basinger, C.L. Thomas, B.C. Shanks, J.D. Caldwell, J.K. Apple, S. Ahuja1, E.A. Backes, and J.J. Hollenbeck

Effects of Breed of Sheep and Dietary Onions on Bitterweed (Hymenoxys odorata DC) Toxicity
Author: E.S. Campbell, T.R. Whitney, C.A. Taylor, Jr., N.E. Garza

Impact of Changes in Weight, Fat Depth, and Loin Muscle Depth on Carcass Yield and Value and Implications for Selection and Pricing of Rams from Terminal-Sire Sheep Breeds
Author: D.R. Notter, M.R. Mousel, H.N. Zerby, L M.M. Surber, T.D. Leeds, S.J. Moeller, G.S. Lewis, and J.B. Taylor

Effect of Fat Source on Growth Performance and Carcass Characteristics of Growing Lambs
Author: P.L. Redding, J.E. Held, C.L. Wright and J.A. Clapper

Article Summaries

High Frequencies of the αS1-Casein Zero Variant in Milk from Swedish Dairy Goats

Author: M. Johansson, M. Högberg and A. Andrén

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Summary
A high concentration of caseins in milk is a prerequisite for a high cheese yield. Over 70 percent of Norwegian Landrace goats have been shown to have a mutation that reduces or removes the ability to produce αS1-casein (αS1-CN), with a subsequent lower cheese yield as a consequence. Swedish Landrace goats are closely related to Norwegian goats, so it is very likely that Swedish goats carry the gene for zero-synthesis of αS1-CN. The objective of this study was to survey the Swedish goat population in order to estimate the frequency of Swedish goats producing low amounts of αS1-CN. By use of capillary zone electrophoresis, milk samples from 283 goats from ten different geographical regions of Sweden were analysed. Sixty-five percent of goats were found to produce low or no concentrations of αS1-CN. Only 12 percent of the dairy goats showed a high expression of this protein.

Key words:
Swedish Goats, αS1-Casein, Capillary Zone Electrophoresis

Effects of Sex, Breed, Callipyge Phenotype, and Docked Tail Length on Rectal Prolapse in Lambs

Author: B. Zanolini1, A.M. Oberbauer, S.D. Prien, M.L. Galyean and S.P. Jackson

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Summary
The objective of this study was to investigate the effects of sex, breed, docked-tail length, and the expression of the callipyge phenotype on the incidence of rectal prolapse in lambs. To test whether these factors influence rectal prolapse in a controlled feedlot environment, lambs (n = 382) representing both sexes and four breed types were assigned randomly to one of three docking treatments: 1) tail removed as close to the body as possible (short-docked, n = 139); 2) tail removed midway between the attachment of the tail to the body and the caudal folds to the tail (mediumdocked, n = 124); and 3) tail removed at the attachment of the caudal folds to the tail (long-docked, n = 119). Incorporating the callipyge phenotype into the study design assessed the effect of enhanced muscle development on rectal prolapse. The overall incidence of rectal prolapse in this study was 2.1 percent. Ewe lambs were no more likely to experience prolapses than male lambs (P > 0.09). Seven of the eight (87 percent; P < 0.01) lambs that prolapsed were hair sheep. No lambs expressing the callipyge phenotype prolapsed. There was no difference (P > 0.05) in rectal prolapse occurrence among the three docking treatments. In this study sex, tail dock length, and muscling did not appear to contribute to rectal prolapse in lambs. However, there may be an over-looked genetic component that influences the occurrence of prolapses in response to the practice of docking.

Key words:
Lambs; Docking; Sheep; Rectal Prolapse; Tail Length

Performance by Yearling Katahdin Ewes Grazing Toxic Tall Fescue Using Either Continuous or Rotational Grazing Schemes in Late Spring Through Summer

Author: E.A. Backes, J.D. Caldwell, B.C. Shanks, K.R. Ness, A.N.V. Stewart, L.S. Wilbers, C.A. Clifford-Rathert, A.K. Busalacki, H.A. Swartz, D.L. Kreider, and M.L. Looper

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Summary
Rotational grazing has increased in popularity; however, this management practice has not been evaluated thoroughly with Katahdin hair sheep. Our objective was to evaluate the effects of continuous or rotational grazing on performance by yearling Katahdin ewes grazing endophyte-infected, tall fescue [Lolium arundinaceum (Schreb.) Darbysh; E+] in late spring through summer. Over two consecutive years, a total of 50 yearling Katahdin ewes were stratified by BW and BCS and allocated randomly to one of five, 0.4-ha E+ pastures on May 5, 2011 and May 7, 2012. Treatments consisted of: 1) continuous (Cont) or 2) 4- cell rotation (4R). Basal cover and forage quality and quantity did not differ (P . 0.19) between treatments. A sampling date effect (P . 0.01) was detected for forage quality and quantity. Grazing d, beginning, end of breeding, and end of the grazing period BW, FAMACHA scores, ADG, total gain, number of lambs/ewe exposed, and lamb birth weight did not differ (P . 0.12) between treatments. Ewe BW and BCS change during the breeding season did not differ (P . 0.17) between treatments. Beginning breeding BCS tended (P = 0.10) to be greater for Cont compared with 4R, but end BCS did not differ (P = 0.45) between treatments. Pregnancy rates and frequency of multiple births were greater (P . 0.04) from 4R compared with Cont. Therefore, utilizing a 4-cell, rotational-grazing system for yearling Katahdin ewes grazing E+ in late spring through summer may improve pregnancy rates and multiple births. However, further studies are warranted.

Key words: Continuous Grazing, Forage Quality and Quantity, Performance, Tall Fescue, Yearling Katahdin Ewes

Effects of Diet Particle Size and Lasalocid on Growth, Carcass Traits, and N balance in Feedlot Lambs

Author: A.R. Crane, R.R. Redden, P.B. Berg and C.S. Schauer

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Summary
The objective of this research was to determine the influence of diet particle size and lasalocid on growth and feed intake, carcass characteristics, and N balance in feedlot lambs. One hundred sixty crossbred (Suffolk x Rambouillet) lambs (31.2 kg ± 0.09 kg) were stratified by weight and sex in a completely random design and allotted to one of 16 pens (n = 4). Lambs were fed a basal feedlot diet consisting of 80 percent corn and 20 percent market lamb pellet ad libitum (AF basis). Diets were whole corn with lasalocid (WCL), whole corn without lasalocid (WCNL), ground corn with lasalocid (GCL), or ground corn without lasalocid (GCNL). Lambs were harvested following the 112 d feeding trial (69.7 kg ± 0.74 kg BW) and carcass data were collected at a commercial abattoir. Final BW, DM offered, G:F, mortality, and the majority of carcass traits were not affected by diets (P ≥ 0.06). Lasalocid-fed lambs had an increase in HCW (P = 0.05). Additionally, there was an interaction of particle size and use of ionophores for ADG (P = 0.05), loin eye area (P < 0.001), and percentage of boneless closely trimmed retail cuts (%BCTRC; P = 0.004). Loin eye area was greatest (P < 0.05) for WCL and GCNL. A second study was conducted utilizing the same diets to evaluate N balance in 16 crossbred wethers (Suffolk x Rambouillet; 40 kg ± 1.7 kg BW; n = 4). Nitrogen balance was not affected by diet (P = 0.22). Our results indicate that HCW in lambs fed lasalocid was increased by 3 percent, while particle size had no major impact on growth, feed intake, carcass traits, or N digestibility.

Key words:
Carcass, Growth, Ionophores, Lasalocid, Particle Size, Sheep

Consumer Evaluation and Shear Force of Retail Domestic Grain-Finished, Imported New Zealand Grass-Finished, and Missouri-Produced Grass-Finished Lamb Racks

Author: K.L. Basinger, C.L. Thomas, B.C. Shanks, J.D. Caldwell, J.K. Apple, S. Ahuja, E.A. Backes, and J.J. Hollenbeck

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Summary
There appears to be increased consumer demand for grass-finished products and elevated preference for locally produced foods, including lamb. Therefore, our objective was to evaluate consumer acceptability and shear force of retail domestic, grain-finished (D); imported New Zealand, grass-finished (N); and Missouri-produced, grass-finished (M) lamb racks. Lamb racks (n = 58) were purchased from three different retailers located in Missouri. After purchase, racks were stored frozen at -20°C for three weeks. Racks were then thawed at room temperature and mechanically fabricated into 2.5-cm thick chops, which were trimmed to include only the longissimus muscle (LM). Three LM chops from each rack were stored at 2°C for two days prior to consumer panel evaluation and two chops from each rack were refrozen (-20°C) for Warner-Bratzler shear-force determination. Consumer panel LM chops were cooked to an internal temperature of 71.1°C on a gas grill and panelists (n = 98) were asked to fill out demographic information and evaluate each sample on a ninepoint hedonic scale (1 = dislike extremely to 9 = like extremely) for each consumer-acceptability trait. Overall acceptability, tenderness, juiciness, flavor, and leanness-acceptability ratings were greater (P < 0.05) from D compared to M and N. Racks from M and N were rated leaner (P < 0.05) than D. All consumer acceptability attributes were similar (P > 0.05) between M and N. Shear-force values from D and N were lower (P < 0.05) compared to M. Therefore, racks from grass-finished lamb may not be evaluated as favorably as racks from grain-finished lamb, but depending on origin, may be as tender as racks from domestic, grain-finished lamb.

Key Words: Grass-Finished, Domestic Grain-Finished, Lamb Rack, Consumer Acceptability

Effects of Breed of Sheep and Dietary Onions on Bitterweed (Hymenoxys odorata DC) Toxicity

Author: E.S. Campbell, T.R. Whitney, C.A. Taylor, Jr. and N.E. Garza

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Summary
Bitterweed (Hymenoxys odorata DC) toxicity is a major cause of death losses in Rambouillet sheep. This study compared the susceptibility of two breeds [Rambouillet and Dorper × Barbados Blackbelly (DBB)], of wool and hair sheep lambs to bitterweed toxicosis; and the potential for cull onions (Allium cepa) to mitigate bitterweed toxicity. Onions contain high concentrations of naturally occurring thiols, thus offering the opportunity for the introduction of a diversionary substrate for the principle toxin, hymenoxyn, in a palatable feedsource. Weanling Rambouillet (n = 12; LS means ± SE = 22.7 kg ± 1.3 kg BW) and DBB (n = 12; LS means ± SE = 22.5 kg ± 0.8 kg BW) ram lambs were assigned randomly to one of four treatments: 0 percent (control), 25 percent, 50 percent, and 75 percent onions in diet (DM basis). The remainder of the isonitrogenous diets consisted of alfalfa pellets to provide 32 g DM/kg BW per day. Animals were group-fed onions for a 10-d preconditioning period, then penned and fed individually for study.Individual onion feeding commenced on d 0 and continued through d 7. On d 3 of onion feeding, lambs were dosed with an aqueous slurry of dried bitterweed (0.25 percent of BW, DM-basis) daily through d 7. Blood samples were taken on d 3 and d 8 and analyzed for serum constituents indicating onion- or bitterweed-induced pathologies, respectively. Dry-matter intake and percentage of feed refusals were measured daily. In response to onion diets, serum urea nitrogen (SUN) decreased linearly (P < 0.001). Concentrations of albumin, aspartate aminotransferase (AST), glucose, hematocrit and total serum protein (TSP) were greater in DBB lambs than in Rambouillet lambs (P < 0.01), but remained clinically normal. The bitterweed challenge elicited a breed effect (P < 0.05) for serum measurements reflective of bitterweed toxicity; bilirubin, gamma-glutamyltransferase (GGT) and AST concentrations were greater (P ≤ 0.001) for DBBs than for Rambouillets. The AST, bilirubin, creatinine, GGT, and SUN were clinically high for all treatments, including controls, indicating acute toxicity. Feed refusals did not differ among treatments or by breed (P > 0.10). In this study, dietary onions did not prevent pathological changes in serum chemistries following bitterweed dosing, and had no influence on feed refusals. Both breeds exhibited clinical signs of bitterweed toxicosis, with DBB sheep exhibiting greater abnormal deviation in serum chemistries than Rambouillets.

Key Words: Bitterweed, Onions, Hair Sheep, Dorper, Barbados Blackbelly, Rambouillet, Toxicosis

Impact of Changes in Weight, Fat Depth, and Loin Muscle Depth on Carcass Yield and Value and Implications for Selection and Pricing of Rams from Terminal-Sire Sheep Breeds

Author: D.R. Notter, M.R. Mousel, H.N. Zerby, L M.M. Surber, T.D. Leeds, S.J. Moeller, G.S. Lewis and J.B. Taylor

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Summary
Breeding objectives and selection indexes are necessary to support comprehensive genetic-improvement programs. This study used off-test body weights (OTBW) or chilled-carcass weights (CCW), ultrasonic measurements of fat depth (USFD, mm), and predicted-ultrasound, loin-muscle depths (USLMD, mm) from 456 wether lambs to predict carcass value and link predictions to estimated breeding values (EBV) of terminal sires. Carcasses were processed by closely trimming high-value cuts (rack, loin, leg, and sirloin), and carcass value (TrCVal) was determined for each carcass. Increasing OTBW had positive effects on carcass value but did not affect dressing percentage (DP). Increasing USFD increased CCW and DP but decreased TrCVal. Increasing USLMD had positive effects on CCW, DP, and TCVal. The EBV for postweaning weight (PWWT), USFD, and USLMD of average and elite Suffolk rams were compared to develop breeding objectives for lambs harvested at a constant time on feed, harvest weight, or harvest fatness, and for a scenario with larger-than-current-price premiums for leanness and muscling. At constant harvest weights, the breeding objective was I2 = 1.2 EBVPWWT – EBVUSFD + 0.8 EBVUSLMD, but changed to I4 = 0.3 EBVPWWT – EBVUSFD + 0.4 EBVUSLMD if carcass price was strongly influenced by leanness and muscling. Genetic correlations among indexes exceeded 0.85. Index I4 was strongly correlated with the Australian LAMBPLAN Carcass Plus index, indicating that selection on Carcass Plus would be effective under U.S. conditions. All indexes were dominated by PWWT EBV. Effects of increasing muscling were substantial, but changing USFD EBV had only modest effects.

Key Words: Breeding Objectives, Carcass Value, Genetic Evaluation, Sheep

Effect of Fat Source on Growth Performance and Carcass Characteristics of Growing Lambs

Author: P.L. Redding, J.E. Held, C.L. Wright and J.A. Clapper

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Summary
Seventy two Polypay crossbred lambs (BW 34.3 ± 0.75 kg) were used in a complete randomized design to determine the effect of supplemental fat source on growth performance and carcass characteristics over a 70-d feeding period. Lambs were stratified by weight and sex and assigned to 12 pens (3 wethers and 3 ewes per pen). Pens were assigned randomly to one of three dietary treatments consisting of 40 percent corn stover, 4 percent soy hulls, 2.4 percent supplement and one of the following treatment combinations: 1) 34 percent low-fat dried distillers grains (CON), 2) 34 percent conventional dried distillers grains plus solubles (DIST), 3) 34.6 percent low-fat dried distillers grains plus 1.85 percent raw corn oil (OIL). DIST and OIL diets were formulated to be iso-lipid. Lambs were allowed ad libitum access to feed and water. On d 21, d 42, and d 63 feeders were emptied and residual feed was weighed, recorded, and sampled. Initial and final BW were determined as the average of weights on d -1 and d 0 (initiation of feeding) and d 69 and d 70, respectively. Three intermediate weights were recorded on d 21, d 43, and d 63 to monitor growth performance. At the conclusion of the feeding period, four lambs were harvested from each pen and carcass data were collected. Cumulative DMI, ADG, G:F, and final BW were similar (P > 0.24) for lambs fed the fatsupplemented diets and the CON diet, however, lambs fed the DIST diet had greater (P < 0.01) cumulative DMI, ADG, G:F, and final BW compared to the OIL diet. Supplementation with corn oil tended (P = 0.06) to decrease HCW compared to supplementation with DDGS, but there were no differences between the CON diet and fatsupplemented diets (P = 0.44). Dressing percentage; backfat thickness; LM area; body wall thickness; USDA-yield grade, and boneless, closely trimmed retail cuts were not affected by fat supplementation or source of fat (P > 0.20). However, lambs were fed a higher energy diet for the last two weeks of the trial to meet target finished-weight goals.

Key Words: Fat, Lambs, Growth, Dried Distillers Plus Solubles