ABSTRACTS

Effect of ruminally protected choline on the growth performance of Alpine doelings

R. Puchala, T. Shenkoru, J. Luo, and T. Sahlu

E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK

The effect of dietary supplementation with ruminally protected choline (RPC) on the growth performance of Alpine doelings was investigated. Thirty-six Alpine doelings (17 wk, 17 ± 1.2 kg BW) were adapted to a completely mixed diet (18% CP, 74% TDN) and allocated to one of three groups on a BW basis. During the experimental period (90 d) the basal diet was supplemented with RPC at 0, 8, and 16 g/kg of DM. Animals received ad libitum access to feed offered twice daily at 1000 and 1500. Average feed consumption (1.15 kg/d) was similar among groups. Average daily gain tended to increase as a result of supplementation at 162, 166, and 172 g/d for 0, 8, and 16 g of RPC, respectively (linear effect, P = 0.10). Feed efficiency was also improved in RPC groups (7.24, 7.04, and 6.84 for 0, 8, and 16 g of RPC, respectively; linear effect, P < .05). Supplementation increased plasma choline concentration (2.96, 4.05, and 4.94 µM for 0, 8, and 16 g of RPC, respectively; linear effect, P < 0.05). In conclusion, the observed improvements in average daily gain and feed efficiency with dietary choline inclusion suggest that choline may be limiting in diets for growing Alpine doelings.

Early growth of Boer x Angora, Boer x Spanish, and Spanish goat kids

J. Luo, M. Cameron, and T. Sahlu

E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK

Boer x Angora (BA; n = 21), Boer x Spanish (BS; n = 30), and Spanish (S; n = 26) male kids were used to compare early growth of Boer crossbred with Spanish goats. Kids were removed from their dams 3 d postpartum and fed goat milk for 2 wk followed by 1.2 kg milk replacer (11.4% DM; 24% CP and 32% fat, DM basis) until weaning at 8 wk. A commercial starter diet (22% CP and 2.8% fat, DM basis; 70% DM digestibility) was consumed ad libitum through 16 wk of age; castration was after 12 wk. Body weight after 2 wk was greater (P < .05) for crossbred vs S goats (4.33, 4.21, and 3.84 kg for BA, BS, and S, respectively). Average daily gain during the milk replacer period (71, 76, and 64 g for BA, BS, and S, respectively) was greater (P < .05) for BA and BS than for S goats. Likewise, ADG (137, 135, and 106 g) and DMI (331, 348, and 265 g/d) during the starter diet period were greater (P < .05) for BA and BS vs S, although gain:DMI was lower (P < .05) for BS than for BA and intermediate (P > .10) for S (.462, .398, and .423 for BA, BS, and S, respectively). In conclusion, differences in ADG between Boer crossbreds and S goats were greater during wk 9 to 16 with starter diet consumption than earlier with milk replacer (wk 2 to 8), and ADG of different Boer crossbreds when young may not differ markedly.

Carcass traits of growing Spanish x Boer kids as influenced by gender and age

M. Cameron¹, T. Sahlu¹, C. Gilchrist¹, S. Hart¹, A. Goetsch^1,3, and S. Coleman²

¹E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK, ²USDA/ARS Grazinglands Research Lab, El Reno, OK, ³USDA/ARS Dale Bumpers Small Farms Research Center, Booneville, AR

Sixty kids (20 intact males, castrates and females) were utilized (3 x 5 factorial) to investigate effects of gender and age on carcass characteristics. Kids consumed ad libitum a corn-based concentrate (80% TDN, 3.6 Mcal/kg DE, 18% CP, and 12% ADF). Twelve kids (four per gender; average age 93-d) were slaughtered initially and at 8-wk intervals for a total of five slaughters (13, 21, 29, 37, 45 wk of age). Live weight (16.4, 22.1, 27.7, 38.8, and 44.4 kg) and hot carcass weight (6.8, 10.8, 13.8, 19.9, and 22.6 kg, respectively) increased linearly (P< 0.001) with age. Dressing percentage, as a percentage of empty BW, increased (P < 0.001) linearly and quadratically with age (50.1, 53.9, 53.5, 55.4, and 54.4%) but was unaffected by sex. Loin eye area (LEA) increased linearly (P < 0.05) with age (7.29, 10.19, 11.10, 13.55, and 13.74 cm²). Digestive organ mass increased linearly (P < 0.001) with age (1.20, 1.39, 1.46, 2.07, and 2.10 kg) but the contribution to empty body mass (8.8, 6.9, 5.7, 5.7, and 5.1%) decreased quadratically (P < 0.001). Gut fill increased quadratically (P < 0.02) with age (2.76, 2.18, 1.89, 2.89, and 2.84 kg). Females had less (P < 0.004) digestive organ mass and fill (organ mass: 1.74, 1.45, and 1.74 kg; fill: 2.75, 2.06, and 2.91 kg for castrates, females and males, respectively). Internal fat increased quadratically with age (0.32, 1.08, 1.60, 2.77, and 4.08 kg). Internal fat comprised 6.9, 7.0, and 5.1% of empty BW for castrates, females and males, respectively. Internal fat deposition, as a percentage of empty BW, showed the greatest increases (P < 0.001) during the early and latter stages of growth (2.3, 5.4, 6.3, 7.7, and 9.9% at 13, 21, 29, 36 and 45-wk). In conclusion, changes in internal fat depostion with advancing age may impact increases in lean tissue accretion by Boer crossbreds.

Performance of growing Spanish x Boer kids as influenced by gender and age

M. Cameron¹, T. Sahlu¹, C. Gilchrist¹, S. Hart¹, and S. Coleman²

¹E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK, ²USDA/ARS Grazinglands Research Lab, El Reno, OK

Sixty Spanish x Boer kids (20 intact males, castrates, and females) were utilized (3 x 5 factorial) to investigate the effects of gender and age on growth performance. Kids were weaned at 10-wk and offered increasing amounts of a starter diet (72% TDN, 3.12 Mcal/kg DE, 20% CP, and 21% ADF) for adaptation to concentrate. After 14-d, kids were placed in individual metabolism crates. After 7-d for adjustment, the experiment was initiated. Kids averaged 16.4 kg and 93-d of age; treatments were balanced for birth and weaning weight, age, and litter size. Kids consumed ad libitum a corn-based concentrate (80% TDN, 3.6 Mcal/kg DE, 18% CP, and 12% ADF). Twelve kids (four per gender) were slaughtered initially and at 8-wk intervals for a total of five slaughters. Performance results at 21, 29, 36 and 45-wk of age are as follows. Dry matter intake (519, 550, 717, and 727 g/d) increased linearly (P < 0.001) with age. Average daily gain (113, 98, 139, and 126 g/d) and feed to gain (F/G)(4.77, 6.32, 5.22, and 5.88) responded to age in a cubic fashion (P < 0.003). Intact males and castrates had greater (P < 0.01) DMI than females (675 vs 533 g/d); males had the greatest (P < 0.001) ADG and were the most efficient (P < 0.004)(ADG: 143, 121, and 93 g/d; F/G: 4.80, 5.93, and 5.91 for males, castrates, and females, respectively). When expressed as a percentage of BW, males had the lowest (P < 0.03) DMI (2.01, 1.98, and 1.89% for castrates, females, and males, respectively). DMI, as a percentage of BW, decreased (P < 0.01) linearly and quadratically with age (2.34, 2.00, 1.85, and 1.66%, respectively); females and castrates exhibited the greatest rate of decline (P < 0.03). No significant gender x age interaction (P > 0.05) was observed for DMI (g/d), BW, ADG, or F/G. In conclusion, results are indicative of a performance advantage for intact males.

Heat production by grazing ewes with low forage mass and supplemental grain

A. L. Goetsch¹, and G. E. Aiken²

¹E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK, ²Dale Bumpers Small Farms Research Center, USDA-ARS, Booneville, AR

Three mature Dorset ewes were used in a 3 x 3 Latin square (two 28-d periods and one 35-d) to determine effects of level of supplemental corn (0, 0.5, and 1.0% BW; DM) on intake, digestion, grazing behavior, and heat production by the whole body and splanchnic and extra-splanchnic tissues with grazing of paddocks low in forage mass. Live and dead forage mass ranged from 1 to 4 kg and 17 to 40 kg DM per 0.036-ha paddock, respectively; initial ewe conditions (urea dilution) were 71 ± 2.5 kg shrunk BW, 47 ± 0.4% fat, and 11 ± 0.1% protein; and in periods 1, 2, and 3, hand-plucked forage samples were 17, 20, and 29% CP and 62, 56, and 58% NDF, respectively. Intake of ME (1.39, 2.32, and 3.16 Mcal/d; SE 0.11) and energy accretion (-1.09, 0.02, and 0.39 Mcal/d; SE 0.224) increased linearly with increasing corn level (P < 0.01 and = 0.04, respectively), and grazing time decreased ((P = 0.06) 76, 63, and 48% of daylight for 0, 0.5, and 1.0% BW of corn, respectively; SE 4.9). However, corn level did not affect (P > 0.10) whole body heat (2.48, 2.30, and 2.77 Mcal/d; SE 0.171), heat increment (0.91, 0.80, and 1.24 Mcal/d; SE 0.172), splanchnic bed heat (1.09, 1.12, and 1.05 Mcal/d; SE 0.091), or extra-splanchnic tissue heat (1.39, 1.18, and 1.72 Mcal/d for 0, 0.5, and 1.0% BW of corn, respectively; SE 0.241). In conclusion, with increasing intakes of corn, total DM, and ME, increased heat produced in dietary energy metabolism for tissue maintenance or maintenance plus energy accretion may only have compensated for decreased grazing-related or -specific heat production by both splanchnic and extra-splanchnic tissues of ewes, resulting in decreased tissue mobilization or increased energy accretion.

Follicle activity and fiber growth patterns of Angora goats in natural photoperiod

A. J. Litherland, C. Toerien, T. Sahlu, and J. Luo

E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK

The objective of this experiment was to describe the seasonal fleece growth cycle in U.S. goats with ambient climatic conditions, and to determine effects of level of feed intake on the cycle. From September 13, 1995 to October 9, 1996, 20 mature, nonpregnant Angora does (30.2 ± 0.9 kg BW; 2.45 ± 0.09 kg 6-mo fleece weight) were maintained in 0.4-ha paddocks (previously heavily stocked for low available forage mass; five does per paddock). In addition, a diet (2.46 Mcal ME/kg and 13.6% CP; DM basis) was offered at an average of 0.53 (L) or 0.68 kg DM/d (H) in order to maintain or slowly increase BW, respectively. Skin sections, for the determination of follicle activity (FA), and patch fleece regrowth samples were collected monthly. Minimum FA occurred 1 mo after the winter solstice and averaged 8 ± 3 and 78 ± 4% in primary and secondary follicles, respectively. Fleece growth rate, fiber diameter, and fleece medullation were 40, 15, and 120% lower (P < 0.05), respectively, in the winter than summer. Fleece growth rate and fiber diameter were maximal 1 mo before the autumn equinox. The H goats had a 20% greater shorn fleece weight than did L goats (P < 0.05). Overall, H and L goats had similar (P > 0.10) clean fiber regrowth rates (1.10 vs 1.02 mg/(cm² · d)^-1), yield (67.5%), and diameter (35.3 vs 33.6 m). Spring primary FA was lower for L compared with H goats (P < 0.05), but secondary FA, follicle medullation, and fleece kemp level were unaffected by level of feed intake (P > 0.10). In conclusion, U.S. Angora goats, with constant levels of feed intake, exhibit seasonal follicle and fiber growth cycles, which may impact efficiency of feed use for mohair growth throughout the year. Level of feed intake can affect fleece weight and seasonal changes in primary FA.

Use of mimosine to induce cashmere shedding in goats

A. J. Litherland, R. Puchala, C. Toerien, and T. Sahlu

E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK

The objective of this experiment was to determine if mimosine treatment of goats at the winter solstice induces shedding of cashmere but not guard hair. Twelve adult cashmere wethers (45 ± 2 kg BW) were continually infused for a 72-h period on December 9, 16, or 23, 1996 (four goats per day), with mimosine (100 mg/kg BW) or saline (C). Primary and secondary follicle activities (FA) on d 0 were 33 ± 8 and 78 ± 7%, respectively. On d 8, cashmere had been shed in three of the six mimosine-treated goats; thus, fiber data were collected from three goats infused with mimosine (M) and from six C goats. Day-8 secondary FA was lower (0 vs 69%; P < 0.001) and cashmere shedding score (SS; 5-point scale, 1 = no shedding, and 5 = excessive shedding) was greater (5.0 vs 1.1; P < 0.001) for M than for C. On d 14, cashmere length was shorter (3.0 vs 8.6 cm; P < 0.01) and guard hair SS was greater (2.3 vs 1.0 cm; P < 0.001) for M compared with C goats. Cashmere yield from M goats was 34 ± 3, 85 ± 4, and 3 ± 1% for pre-combed, combed, and post-combed fleeces, respectively. In January and February, secondary FA (> 98 vs 37 to 52%; P < 0.05) and cashmere growth rate ((i.e., based on length of nonshed fiber) 1.10 vs -0.22 mm/d; P < 0.05) were greater for M vs C goats. Over the January to April period, cashmere SS was lower (P < 0.01) for M than for C goats (1.13 vs 1.55). The guard hair fleece was 1 cm shorter (P < 0.05) for M compared with S goats in February and March. In conclusion, M was effective at removing cashmere in 50% of the goats treated; secondary FA in cashmere-shedding goats was increased by M, which led to additional cashmere growth.

Effects of testing lab, counting method, storage and shipment on somatic cell counts of goat milk

S.S. Zeng¹, E.N. Escobar¹, S.P. Hart¹, L. Hinckley², M. Baulthaus³, G.T. Robinson⁴, and G. Jahnke⁵

¹E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK, ²Department of Pathology, University of Connecticut, Storrs, CT, ³DQCI Services, Inc., St. Paul, MN, ⁴Texas Milk Marketing Order, Carrollton, TX, and ⁵Dairy Laboratory Services, Dubuque, IA

Somatic cell counts (SCC) in goat milk from different stages of lactation were determined at four laboratories using the pyronin Y-methyl green (PYMG) direct microscopic method and(or) Fossomatic machines calibrated with either goat or cow milk standards. The effects of sample shipment and storage on SCC of goat milk were also determined. Results of this study indicated that the PYMG microscopic method and the Fossomatic machine calibrated with goat milk standards gave comparable estimates of SCC in goat milk (P > 0.05). However, on average the Fossomatic machines (n = 3) calibrated with cow milk standards estimated SCC of goat milk to be 24.5% higher than a Fossomatic machine calibrated with goat milk standards (P < 0.05). No significant difference in SCC of goat milk existed (P > 0.05) between laboratories (n = 2) when the PYMG microscopic method was used. Shipping milk samples in an ice box (a 3-day round trip) and storing in a refrigerator (3 days) did not affect SCC results (P > 0.05).

Nutrient comparison of goat, cow and human milk: an update

S.S. Zeng

E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK

Goat milk is consumed by a larger proportion of the world's population than cow milk. Goat milk not only provides a vital part of the complete nutritional requirements to people in developing countries but is also used as an alternative for the people in the whole world who are allergic to cow milk. Recently, the Nutrient Data Laboratory of USDA's ARS published "USDA Nutrient Database for Standard Reference (Release 11-1)" covering thousands of food items. The data regarding goat, cow and human milk were compiled from published and unpublished sources around the world. In this paper, goat, cow and human milks are compared specifically in their profiles of major components, fatty acids, amino acids, minerals and vitamins. The merits of goat milk in nutrient values are also discussed. It is obvious that goat milk is a wholesome, natural, traditional and nutritious food commodity. The unique composition of goat milk and its nutrient values in human requirements make it extremely valuable for infants who are allergic to cow milk, for children who have general food allergies, for adults who are recovering from illness and for the elderly who have digestion difficulties. "Goat milk may be favored as a staple food source by more individuals in the coming decade."

Implications of DHIA for dairy goats

I. E. Brown-Crowder

E (Kika) de la Garza Institute for Goat Research, Langston Univeristy, Langston, OK

A small survey of Oklahoma dairy goat producers and American Dairy Goat Association (ADGA) Directors was conducted to evaluate their knowledge of Dairy Herd Improvement (DHI) programs. Of the 50 herds surveyed, comprising a total of 2,208 goats, 40% do not use DHI testing for goats due to lack of tester availability or the overall program costs. Of the 60% on DHI test, 67% utilize an official tester while 32% circle or group test (three or more producers test each other). All of the herds utilizing an official tester were on standard test. Of the herds surveyed, 55% rated the overall knowledge and service of their tester and local DHI Association management to be high. However, 55% of the producers rated the overall service of State DHI Association organization and laboratory to be fair to poor. Most producers ranked production statistics, genetic information, and management information as the top three factors of importance to DHI test. Milk quality, reproduction, milk production, feed management, and health information were found to be the most useful components of DHI records. The use of somatic cell counts as an indication of udder infection was considered unreliable for goats by 60% of those surveyed. Of the 40% not utilizing DHI, 60% would go back on test if there was a goat specific program. Of those surveyed, 25% would be interested in the AM/PM Timer (APT) testing plan. Of the sampled population, 50% would accept a disinterested third party for verification testing. According to USDA-AIPL, the number of goat herds and does on DHI plans decreased from January 1, 1997 (728, 14,097) to January 1, 1998 (606, 11,840), respectively. In summary, dairy goat producers could benefit from goat specific DHI paperwork and more economical testing programs, better DHI service and optional testing plans to increase the number on DHI test. Further research is needed to evaluate DHI testing plans such as AM/PM, Standard, and Every Other Month for dairy goats.