Introduction

The improved Boer goat of South Africa has a large mature size and high growth rate. These two qualities have made the Boer goat very attractive to American meat goat producers as a means of improving existing goat herds and overall production. Little information exists regarding the performance and nutritional management of the Boer goat in the U.S. However, to achieve its growth potential, the Boer goat may require more intensive management than that currently practiced in the U.S. Utilizing the popular Spanish cross, the authors investigated the effect of both age and sex on growth rate, feed efficiency, and carcass quality of Spanish x Boer kids under intense management (i.e., feedlot conditions).

Procedures

Sixty Spanish x Boer kids (20 intact males, castrates, and females) were used. Kids were raised on pasture with their dams until being weaned at 10 wk of age. Kids were then slowly adapted to a high concentrate diet over a period of 3 wk. Kids were then placed in individual pens. Kids consumed ad libitum a corn-soybean meal-based concentrate (80% TDN, 18% protein, and 12% ADF). Feed intakes were recorded daily. Kids were weighed every 2 wks. Twelve kids (four per sex) were slaughtered at 13, 21, 29, 36, and 45 wk of age.

Results

Table 1. Production characteristics of growing Spanish x Boer kids.

Item	Age at Slaughter (wk)
	13	21	29	36	45
Weight, lb
Intact males	37	52	71	95	112
Females	33	43	52	71	79
Castrates	37	52	59	90	98
Feed intake, lb/d
Intact males	---	1.2	1.5	2.0	2.2
Females	---	.9	1.2	1.4	1.6
Castrates	---	1.3	1.4	2.0	2.0
Average daily gain, lb/d
Intact males	----	0.26	0.31	0.34	0.35
Females	----	0.18	0.17	0.24	0.21
Castrates	----	0.29	0.17	0.33	0.27
Feed:Gain
Intact males	----	4.3	4.7	4.9	5.4
Females	----	5.5	6.5	5.6	6.1
Castrates	----	4.6	7.8	5.1	6.2

Table 2. Carcass characteristics of growing Spanish x Boer kids.

Item	Age at Slaughter (wk)
	13	21	29	36	45
Carcass weight, lb
Intact males	15	25	35	47	55
Females	15	21	26	37	43
Castrates	15	26	30	48	51
Dressing percentage, %
Intact males	41	48	49	50	50
Females	43	48	50	52	52
Castrates	41	50	50	52	51
Carcass lean, %
Intact males	39	49	47	48	48
Females	46	48	46	47	48
Castrates	45	48	46	48	48
Carcass fat, %
Intact males	19	26	27	28	28
Females	24	23	24	24	27
Castrates	20	23	25	27	25
Internal fat, lb
Intact males	0.7	2.2	3.6	5.3	7.9
Females	0.9	2.0	3.5	5.1	9.2
Castrates	0.7	2.9	3.5	7.7	9.7

Discussion

In terms of performance, intact males had greater body weight gain and feed intake. Male kids were also the most efficient in converting feed to body mass. Therefore, it is more economical to market intact males than castrates, especially at younger ages when buck taint of the meat is not a factor. The Spanish x Boer kids also exhibited feed:gain ratios comparable to those of lambs and steers. Spanish x Boer kids dressed out slightly less than lambs but, contrary to popular belief, showed significant amounts of carcass fat. The predominance of internal fat gains at younger ages is reflected by inefficient gain during this period; restricting feed intake or feeding less grain during the early stages of growth may be more economical. The optimum levels of both feed intake and diet composition for the various stages of growth in Boer crossbreds needs to be determined. The ability to lay down appreciable quantities of carcass fat means that goats are capable of marbling and that it may be possible to use nutrition to enhance both quality, palatibility, and flavor of goat meat; more research is needed in this area.