Agriculture Reference
In-Depth Information
Table 15.4
Heritability values and phenotypic correlations for Cashmere goat traits.
Trait
Trait
1
BW
GFW
DY
DW
DAFD
Heritability range
2
0.22 - 0.29
0.25 - 0.45
0.23 - 0.90
0.36 - 0.61
0.47 - 0.83
Average heritability
3
0.26 (0.57)
0.35 (0.36)
0.49
0.45 (0.69)
0.67 (0.42)
Phenotypic correlations
2
BW
—
0.23
−
0.11
0.05
0.13
GFW
0.10
0.64
0.31
DY
0.79
0.35
DW
0.46
1
BW = body weight, GFW = grease fl eece weight, DY = down yield, DW = down weight, and DAFD = down
average fi ber diameter
2
As reported by Pattie and Restall, 1992.
3
Average of four studies cited by Pattie and Restall, 1992 (data in parenthesis from Ma Ning et al., 1996).
Environmental, Nutritional, Age, and Sex
Infl uences on Fiber Production
common and necessary practices in the major producing
countries.
From birth to about 4 years of age, mohair fi bers become
progressively coarser, after which time, the average fi ber
diameter remains fairly constant. After 4 years of age,
Angora does begin to produce less mohair. Some follicles
stop producing altogether. In summary, in the age range
1.5-6.5 years, the effects of age are positive for BW, clean
yield, average fi ber diameter, and med and kemp content,
and are negative for fl eece weight (Lupton et al., 1996).
Mature
A
NGORA
G
OAT
Although photoperiod infl uences growth rate of mohair
(and cashmere), nutrition, as infl uenced by climatic and
grazing conditions and supplementation, usually has a
much greater effect. Mohair growth is lowest in winter and
highest in summer (Litherland et al., 2000). In fact some
follicles produce no mohair at all during the winter period.
Mohair fl eeces shorn in February (grown in autumn and
winter) are typically lighter in weight, and are shorter,
fi ner, and less kempy than those shorn in August (grown
predominantly in spring and summer).
Mohair production by kids and mature animals is infl u-
enced greatly by the amount and composition of the diet.
In fact, nutritional variation within and between years is
the most important environmental factor infl uencing fi ber
production and properties. Inadequate nutrition causes
less, shorter, and fi ner fi bers to be produced. Unless goats
are on a very high plane of nutrition, mohair production
and average fi ber diameter invariably respond positively
to protein and rumen-protected amino acid (for example,
encapsulated methionine) supplementation. However, the
most strategic and economically rewarding use of protein
supplementation may be to assist female kids in attaining
a successful mating weight by the time they are 18 months
of age (Huston et al., 1993). Energy supplementation is
indicated whenever the welfare of the goats is at risk. Thus,
energy supplementations to pregnant and lactating does
and to reduce weight loss during drought have been
females
produce
2 - 2.5 kg
of
greasy
mohair
(average fi ber diameter approximately 34
m) every 6
months, this being under genetic and nutritional control to
varying degrees. In contrast, kids (6 and 12 months of age)
typically produce less than 1 kg at their fi rst shearing and
between 1 and 1.5 kg at the second shearing (22 to 29
μ
m).
In a 6-month period, the fi ber grows to a length of 10-
15 cm, this being a requirement for worsted (long-staple)
processing. Age and body weight are correlated with each
other and fi ber diameter when nutrition is adequate.
However, when nutrition is poor, body weight becomes a
more accurate predictor of fi ber diameter. Males having
greater body weights than females tend to produce more,
coarser, and longer mohair than females of similar age
maintained under similar conditions. Pregnant and lactat-
ing Angora does tend to produce less and fi ner mohair than
comparable nonpregnant does.
μ
C
ASHMERE
G
OAT
Cashmere growth rate declines linearly from midsummer
to early winter when the fi bers stop growing altogether and
