|
| |
Preliminary assessment of Boer and Kiko does
as maternal lines
for kid performance under humid, subtropical conditions
R. Browning, Jr.#, S.H. Kebe and M. Byars
Institute of Agricultural and Environmental Research,
Tennessee State University, 3500 John A. Merritt Blvd., Nashville, TN 37209, USA
Abstract
Thirty Boer and 27 Kiko does were exposed to Spanish bucks and evaluated for doe
reproduction, preweaning kid growth, and production efficiency in the humid,
subtropical south-eastern United States. Does of each breed were represented by
at least seven seed stock farms and eight sires. Twenty-five Boer and 23 Kiko
does gave birth to at least one live kid. Body weights at parturition were
heavier for Boer than Kiko dams. Litter size and litter weight were similar at
birth for Boer (1.92 ± 0.12 kids, 6.05 ± 0.31 kg) and Kiko dams (1.82 ± 0.12
kids, 5.90 ± 0.33 kg). Birth weights were similar between 46 Boer and 42 Kiko F1
kids. Birth weights were heavier for single than for twin kids; twin kids were
heavier at birth than triplet kids. Bucks were heavier than does at birth. At
least one kid was reared to weaning by 20 Boer and 21 Kiko dams. Body weights at
weaning were similar for dam breeds. Litter size, litter weight, and litter
weight to doe weight ratio were significantly greater for Kiko (1.85 ± 0.09
kids, 31.73 ± 1.52 kg, 78.1 ± 4%) compared with Boer dams (1.58 ± 0.09 kids,
26.48 ± 1.51 kg, 63.9 ± 4%) at weaning. Pre-weaning growth rates and weaning
weights were greater for 38 Kiko compared with 32 Boer F1 kids and were greater
for bucks than for does. Kiko F1 kids had significantly lower attrition rates
(9.5%) and Kiko does had significantly fewer episodes of lameness (1.60 ± 0.33
episodes/doe) compared with Boer (34.8%, 3.31 ± 0.31 episodes/doe).
Kiko dams tended to wean a higher kid crop percentage and weaned higher litter
weights per doe exposed compared with Boer dams. Significant variation existed
between Boer and Kiko as maternal breeds for performance, efficiency, and
fitness under these research conditions.
Introduction
In the United States, goat production is characterized as a non-traditional,
alternative agricultural enterprise. The meat goat is an emerging class of
livestock offering U.S. farmers a new option for on-farm income. Major
determinants of profitability in a meat goat enterprise are reproductive and
maternal abilities of the doe herd. Genetic composition of does may affect the
performance of progeny. The improved Boer goat from South Africa (Casey & Van
Niekerk, 1988; Campbell, 2003) is a breed developed for meat production that
evolved from selection pressures placed on common goats of the region by
farmers.
Exportation of Boer goats to the U.S. in the mid-1990s helped to stimulate
interest in meat goat production. No goat breeds in the U.S. had been developed
specifically for meat production; milk, fibre, and brush control were the
primary reasons of raising goat with meat being a by-product. The Kiko from New
Zealand (Batten, 1987) is another goat breed exported to the U.S. in the
mid-1990s that was developed for meat production. The Kiko breed developed from
the systematic breeding of selected New Zealand feral does with dairy bucks,
further crossbreeding and interbreeding at the F2 and F3 generations, and breed
establishment at the fourth generation (Batten, 1987). Exportations of Boer and
Kiko goats have created an opportunity for goat producers internationally to
introduce the germplasm of new meat breeds into their breeding programs.
Reproduction and maternal ability are important economic traits to consider when
evaluating the strengths and weaknesses of a new breed. When assessing new
breeds for genetic merit in meat animal production systems, the maternal side is
often overlooked. Breed of dam genetics can influence the performance of any
sire's progeny. Meat goat dam breeds likely differ for general production
efficiency in a given production environment as documented in sheep (Bourfia &
Touchberry, 1993; Bunge et al., 1995; Dimsoski et al., 1999). Maternal breed has
not received much attention in the area of meat goat production. Breed of dam
has been shown to affect body weight, growth from birth through the post-weaning
period and carcass traits for the progeny of Boer sires and dairy breed sires (Ruvuna
et al., 1992; Waldron et al., 1996; Goonewardene et al., 1998; Ward et al.,
1998). Percentage Boer does did not outperform Spanish does under range
conditions (Ward et al., 1998). Studies involving Kiko-influenced does have not
been published to date in the scientific literature. The reported breed of dam
effects on kid performance were largely based on absolute weights and not
adjusted for dam weight to measure production efficiency. Reproductive and
maternal merits should be considered when making breed of dam choices. The
semi-arid origin of the Boer and humid origin of the Kiko are distinctions that
may influence the merits of these breeds in a given environment. This project
focused on reproductive and maternal abilities of Boer and Kiko does under the
humid, subtropical climatic conditions of the southeastern United States.
Materials and Methods
In the autumn, 30 Boer and 27 Kiko does were exposed to three Spanish bucks in
single-sire breeding groups to begin evaluating meat goat breeds of doe for
reproductive rates, pre-weaning kid growth, and production efficiency. Each
breed of doe was represented by at least seven seedstock farms and eight sires.
Does were nulliparous or primiparous purebreds under two years old with age and
parity balanced across breeds. All goats were managed on the Tennessee State
University research station in Nashville, Tennessee, USA (36°17'N, 86°81'W).
Nashville is 183 m above sea level and receives an annual rainfall of 1222 mm.
The 12-month rainfall during the study (September, 2002 to August, 2003) was
1552 mm.
Does were managed in pastures that provided tall fescue (Festuca arundinacea)
for limited grazing supplemented with orchardgrass hay (Dactylis glomerata; 110
g CP/kg, 50% TDN, estimated as-fed) for ad libitum consumption and 682 g/d of a
commercial concentrate (160 g CP/kg, 69% TDN, as-fed) medicated with monensin.
Does kidded on pasture without intervention. The spring-born kids were not
creep-fed and bucks were not castrated before weaning. Dams and kids were
weighed at birth and at weaning (14 wk).
Animal weights, litter size, production efficiencies and hoof care for lameness
were statistically tested by analysis of variance. Kid crop percent was
determined by litter size at weaning divided by number of does exposed.
Individual doe health records were maintained, from which cases of lameness and
subsequent hoof treatments were obtained. Kid attrition was analysed by
chi-square. Kid attrition included pre-weaning kid mortality, excluding
stillborns, and kids orphaned due to dam mortality.
Results and Discussion
At kidding, 25 Boer and 23 Kiko does produced at least one live kid. Stillborns
were not included in birthing datasets. Boer dams at kidding were heavier (P =
0.06) than Kiko dams (48.49 ± 1.25 vs. 45.04 ± 1.32 kg). Litter size and litter
weight at birth did not differ (P > 0.5) between Boer (1.92 ± 0.12 kids, 6.05 ±
0.31 kg) and Kiko dams (1.82 ± 0.12 kids, 5.90 ± 0.33 kg). Kid birth weights
were similar (P = 0.43) between 46 Boer and 42 Kiko F1 kids (3.21 ± 0.09 vs.
3.29 ± 0.08 kg). Each litter type differed (P < 0.001) for kid birth weights
(singles = 3.84 ± 0.14, twins = 3.23 ± 0.06, triplets = 2.67 ± 0.13 kg). Bucks
at birth were heavier (P < 0.01) than does (3.40 ± 0.08 vs. 3.10 ± 0.09 kg).
Birth traits were generally similar for the dam breeds.
Pre-weaning growth rates and weaning weights were greater (P = 0.04) for 38 Kiko
F1 kids (140.4 ± 4.61 g/d, 16.81 ± 0.51 kg) compared with 32 Boer F1 kids (126.5
± 5.97 g/d, 15.29 ± 0.65 kg). Bucks had higher (P < 0.01) pre-weaning growth
rate and weaning weights (145.2 ± 4.3 g/d, 17.29 ± 0.47 kg) than does (121.7 ± 6
g/d, 14.81 ± 0.66 kg). Kids orphaned before weaning were not included in the
weaning kid dataset. Kid attrition rates before weaning were higher (P < 0.01)
for Boer than for Kiko (34.8 vs. 9.5%).
These data indicate that pre-weaning performance of the Spanish-sired kids was
enhanced by Kiko dams. Twenty Boer and 21 Kiko dams reared at least one kid to
weaning. Boer and Kiko dam body weights at weaning did not differ (P = 0.35;
42.42 vs. 40.75 ± 1.25 kg). Weaning litter size was smaller (P = 0.05) and
litter weaning weight was lower (P = 0.02) for Boer (1.58 ± 0.09 kids, 26.48 ±
1.51 kg) than for Kiko dams (1.85 ± 0.09 kids, 31.73 ± 1.52 kg). The ratio of
litter weight weaned to doe weight at weaning was greater (P = 0.01) for Kiko
compared with Boer dams (78.1 vs. 63.9 ± 4%). In terms of overall herd
efficiency, Kiko does tended (P = 0.10) to wean a higher kid crop percent and
weaned a heavier (P = 0.07) litter weight per doe exposed (125 ± 19%, 21.55 ±
3.05 kg) compared with Boer does (86 ± 19%, 14.77 ± 2.96 kg). During the
12-month period, Boer does had more (P < 0.001) episodes of lameness requiring
hoof care than Kiko does (3.31 ± 0.31 vs. 1.60 ± 0.33 episodes/doe). Performance
comparisons appeared to favour the Kiko does under these research conditions.
Boer goats have been used extensively in the U.S. over the last 10 years for
crossbreeding with the goal of enhancing growth and conformation of market kids.
In the process, the Boer influence has become pronounced in U.S. commercial
herds as Boer-cross does are retained as replacements. The substantial numbers
of Boer-cross does in commercial herds and purebred Boer does raised in the
seedstock and commercial operations necessitate an evaluation of this breed for
maternal ability under U.S. production conditions. In simulation work of
Blackburn (1995), the production environment determined if Spanish or Boer does
were more productive and efficient as genetic × environment interactions
existed. Unlike the Boer goat that evolved under semi-arid to arid conditions,
the Kiko goat was developed in a humid environment. Environmental adaptations of
the Kiko goat are speculated as contributing to its fitness and performance at
this research location which is situated in the humid, subtropical climate zone
of the south-eastern United States. Comparatively higher pre-weaning kid
attrition rates and greater hoof care requirements of the Boer further suggest
that the Boer may be less adapted to a humid environment. Poor environmental
adaptation could negatively influence performance. The evaluation of various doe
breeds for performance within unique environmental settings is warranted.
Conclusions
This project was designed to evaluate Boer and Kiko does for economically
important production traits under the humid, subtropical conditions of the
south-eastern United States. The Kiko exhibited greater performance levels and
efficiencies compared with the Boer for doe-kid performance. These initial
results suggest that Kiko does would be a viable breed option to enhance doe-kid
performance in commercial meat goat production systems of the humid subtropics.
The reader is cautioned, however, that the current dataset is
based on a rather small sample, thus is preliminary in character at this stage
of the study. Nevertheless, results highlight the need to evaluate new breeds
under unique environmental conditions for doe fitness, reproductive and maternal
traits that are important to commercial meat goat production.
References
Batten, G.J., 1987. A new meat goat breed. In: Proc. 4th Int. Conf. on Goats.
Brasilia, Brazil. Vol. 2, pp. 1330-1336.
Blackburn, H.D., 1995. Comparison of performance of Boer and Spanish goats in
two U.S. locations. J. Anim. Sci. 73, 302-309.
Bourfia, M. & Touchberry, R.W., 1993. Diallel cross of three Moroccan breeds of
sheep: I. Lamb growth and carcass traits. J. Anim. Sci. 71, 870-881.
Bunge, R., Thomas, D.L. & Nash, T.G., 1995. Performance of hair breeds and
prolific wool breeds of sheep in southern Illinois: lamb production of F1 adult
ewes. J. Anim. Sci. 73, 1602-1608.
Campbell, Q.P., 2003. The origin and description of southern Africa's indigenous
goats. S. Afr. Soc. Anim. Sci. Popular Scientific Papers. Vol. 4, pp. 18-22.
http://www.sasas.co.za/scientific/campbell.pdf
Casey, N.H. & Van Niekerk, W.A., 1988. The Boer Goat I. Origin, adaptability,
performance testing, reproduction and milk production. Small Rumin. Res. 1,
291-302.
Dimsoski, P., Tosh, J.J., Clay, J.C. & Irvin, K.M., 1999. Influence of
management system on litter size, lamb growth, and carcass characteristics in
sheep. J. Anim. Sci. 77, 1037-1043.
Goonewardene, L.A., Day, P.A., Patrick, N., Scheer, H.D., Patrick, D. &
Suleiman, A., 1998. A preliminary evaluation of growth and carcass traits in
Alpine and Boer goat crosses. Can. J. Anim. Sci. 78, 229-232.
Ruvuna, F., Taylor, J.F., Okeyo, M., Wanyoike, M. & Ahuya, C., 1992. Effects of
breed and castration on slaughter weight and carcass composition of goats. Small
Rumin. Res. 7, 175-183.
Waldron, D.F., Willingham, T.D. & Thompson, P.V., 1996. A comparison of Angora
and Spanish does for producing crossbred goats for slaughter: effects on growth
rate and feed efficiency. Combined Research Reports: Sheep and Goat, Wool and
Mohair, 1996. CPR 5257. Texas Agricultural Experiment Station, College Station,
TX, USA.
Ward, B.J., Waldron, D.F., Willingham, T.D., Hallum, C.R. & Casey, J.E., 1998.
Factors affecting birth weight and weaning weight in kids of Spanish and
Boer-Spanish does. J. Anim. Sci. 76 (Suppl. 1), 77
(Abstr.).
The South African Journal of Animal Science is available online at http://www.sasas.co.za/sajas.html
|