Small Ruminant Research 35 (2000) 133±139
Growth and cashmere production by Spanish goats consuming ad
libitum diets differing in protein and energy levels
D.S. Iveya, F.N. Owensb, T. Sahlua,*, T.H. Teha, P.L. Claypoolc, A.L. Goetscha
a
E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK 73050, USA
b
Animal Science Department, Oklahoma State University, Stillwater, OK 74078, USA
c
Department of Statistics, Oklahoma State University, Stillwater, OK 74078, USA
Accepted 11 June 1999
Abstract
Thirty-six Spanish goat wethers (196 12.9 days of age and 17.5 4.60 kg BW at experiment initiation) from a herd
previously selected for cashmere growth were used to determine effects and interactions of ad libitum consumption of diets
differing in concentrations of CP (10% and 15%) and ME (2.00, 2.35 and 2.70 Mcal/kg; DM basis) on growth and cashmere
®ber production in an 84-day, fall-season experiment. DM intake was greater (P < 0.05) for diets with 15% vs. 10% CP (736
vs. 655 g/day) but similar among ME concentrations (P > 0.10). ADG was greater (P < 0.02) for 15% vs. 10% CP (79 vs. 53 g/
day) and increased linearly (P < 0.10) as dietary ME level increased (58, 62 and 78 g/day for 2.00, 2.35 and 2.70 Mcal/kg ME,
respectively). Total ¯eece weight at the end of the experiment was similar (P > 0.10) between CP levels but increased linearly
(P < 0.03) as ME concentration in the diet increased (197, 239 and 227 g/day). Guard hair weight was not affected by dietary
treatments (P > 0.10); cashmere length was similar among treatments (P > 0.10); and cashmere ®ber diameter was not altered
by dietary ME level (P > 0.10) but was greater (P < 0.05) for 15% vs. 10% CP (16.92 vs. 16.06 mm). Cashmere weight was
in¯uenced by an interaction between CP and ME levels (P < 0.05); cashmere ®ber weight with 10% CP was 92, 82 and 95 g,
and with 15% CP was 63, 115 and 99 g for 2.00, 2.35 and 2.70 Mcal ME/kg diets, respectively (SE ˆ 10.2). However, the
ranking of treatment means for initial cashmere ®ber weight was similar to that at the end of the experiment, although
differences at the beginning were non-signi®cant and of lesser magnitude than at the end. In conclusion, further research with
in¯uences of concentrations of CP and ME in diets consumed ad libitum on cashmere ®ber growth of growing US Spanish
wether goats is required, and animal numbers and allocation to treatments deserve careful consideration in studies of cashmere
®ber production. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Cashmere; Goat; Energy; Protein
1. Introduction
*Corresponding author. Tel.: +1-405-466-3836; fax: +1-405466-3138.
E-mail address: [email protected] (T. Sahlu).
Research with Australian feral goats, of unknown
breed origin and unselected for cashmere ®ber growth,
has shown little or no effects of plane of nutrition on
cashmere ®ber production with basal nutritional
0921-4488/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 9 2 1 - 4 4 8 8 ( 9 9 ) 0 0 0 8 4 - X
134
D.S. Ivey et al. / Small Ruminant Research 35 (2000) 133±139
planes adequate for BW maintenance (Ash and
Norton, 1984, 1987a,b; KloÈren et al., 1993). Responses
in total ¯eece production, when noted, have been
attributable to hair growth by primary follicles. However, it is unclear if such ®ndings are of similar
applicability to other breeds or types of goats that
grow cashmere ®ber or with other production conditions.
Most non-Angora breeds or types of goats in the
USA grow cashmere ®ber (Litherland and Sahlu,
1997). The type of goat used for cashmere ®ber
production most frequently in the USA is the Spanish.
The Spanish goat herd of Langston University was
selected for cashmere growth for several years preceding this experiment and, therefore, might differ
from Australian feral goats in responses to dietary
variations. In addition, interactions between dietary
protein and energy levels with ad libitum feed intake
in effects on cashmere ®ber growth have not been
extensively investigated. Ash and Norton (1984) studied interactions between protein and energy intakes
in cashmere ®ber growth in young Australian feral
goats; however, energy intake was varied through ad
libitum vs. restricted consumption of a pelleted diet.
Moreover, the proportion of ingested ME available to
non-visceral tissues may differ between restricted
intake of a particular diet and ad libitum consumption
of diets varying in ingredient composition and
between pelleted and other diet physical forms
(Goetsch, 1998). Thus, the objective of the present
experiment was to evaluate the effects and interactions
of ad libitum consumption of diets differing in CP and
ME concentrations on growth and cashmere ®ber
production by young/growing US Spanish wether
goats.
2. Materials and methods
2.1. Animals and treatments
Thirty-six cashmere-producing Spanish wether
goats were housed individually in 1.2 m 1.2 m pens
during an 84-day experiment following a 3-wk preliminary period (September±January). Wethers were
from the Spanish goat herd of Langston University,
which had been selected for cashmere ®ber production
for the preceding several years. Room temperature
was held constant at 218C with 9 h of light and 15 h of
dark, with light beginning at 0800 h. BW was measured on two consecutive days and goats were sheared
at the beginning and end of the experiment. Initial age
and BW were 196 12.9 days and 17.5 4.60 kg,
respectively. During the preliminary period, goats
consumed ad libitum a diet with 10% CP and
2.35 Mcal/kg ME (DM basis). Thereafter, animals
were blocked into six initial BW groups and assigned
randomly within group to the six treatments.
The treatment arrangement was a 2 3 factorial.
Diets were formulated to be 10% or 15% CP and 2.00,
2.35 or 2.70 Mcal/kg ME (DM basis; Table 1). Soybean meal replaced rolled oats and a small amount of
ground corn to vary the CP concentration, and ground
corn substituted for cottonseed hulls to derive different
ME concentrations. Diets were completely mixed
(Weigh-Tronix, Fairmont, MN) and offered once daily
(0900 h) at approximately 110% of consumption on
the preceding few days. Feeders were emptied and orts
weighed twice weekly; feed and ort samples were
collected once weekly and composited by 28-day
period.
2.2. Samples and analyses
Feed and ort samples were dried for 48 h at 658C,
allowed to air equilibrate and ground in a Wiley mill
to pass a 1 mm screen. Samples were analyzed for
DM (AOAC, 1990), N (Technicon, Tarrytown, NY),
GE (adiabatic bomb calorimeter; Parr Instrument,
Moline, IL), ADF and NDF (Goering and Van Soest,
1970). Ort composition (data not shown) was similar
to that of diets offered and, therefore, not used for
correction.
At shearing, total ¯eece weight was recorded and a
representative ¯eece sample was taken. A Shirley
Analyzer was used to determine the proportion of
cashmere ®ber that can be mechanically separated
from coarse guard hair as previously described by
Lupton (1993). For cashmere length measurement,
two 1 g aliquots were randomly sampled and manually
separated into cashmere and hair ®bers. Cashmere
®ber length was measured under a microscope to
the nearest 0.5 mm and cashmere ®ber diameter
was measured using an Optical Fiber Diameter Analyzer (Baxter et al., 1992).
D.S. Ivey et al. / Small Ruminant Research 35 (2000) 133±139
135
Table 1
Composition of diets consumed by growing Spanish wethers
Item
Diet (%DM)
10% CP,
10% CP,
10% CP,
15% CP,
15% Cp,
15% CP,
2.00 Mcal/kg ME 2.35 Mcal/kg ME 2.70 Mcal/kg ME 2.00 Mcal/kg ME 2.35 Mcal/kg ME 2.70 Mcal/kg ME
Ingredient composition
Ground corn
6.21
Cottonseed hulls
55.35
Rolled oats
24.31
Soybean meal
7.55
Alfalfa meal
3.64
Limestone
0.58
Dicalcium phosphate 1.16
Trace mineral salta
0.58
Vitamin premixb
0.62
30.11
39.75
17.68
8.13
1.96
0.47
0.93
0.47
0.50
61.22
18.19
9.99
6.20
2.00
0.47
0.95
0.47
0.51
5.13
57.13
5.02
24.67
5.02
0.60
1.19
0.60
0.64
15.49
38.86
18.19
23.00
2.02
0.48
0.96
0.48
0.52
47.09
18.65
7.37
20.98
3.68
0.44
0.88
0.44
0.47
Nutrient composition
DM (% as-fed)
91.0
CP (% DM)
9.71
ADF (% DM)
39.8
Ash (% DM)
4.64
ME (Mcal/kg)c
2.01
S (% DM)c
0.15
N : S ratioc
19.5
90.0
9.57
31.1
3.72
2.34
0.15
17.0
90.3
9.99
16.4
3.80
2.71
0.14
15.3
91.2
14.83
38.6
5.25
2.04
0.17
25.0
90.5
14.87
25.8
4.50
2.34
0.18
20.2
90.8
15.19
17.9
4.18
2.70
0.18
18.2
a
95±98.5% NaCl and >0.24% Mn, 0.24% Fe, 0.05% Mg, 0.032% Cu, 0.011% Co, 0.007% I and 0.005% Zn.
2200 IU vitamin A, 1200 IU vitamin D3 and 2.2 IU vitamin E/g.
c
ME and S were calculated from NRC (1981).
b
2.3. Statistical analyses
Data were analyzed with the GLM procedure of
SAS (1985) as a randomized complete block design
(Cochran and Cox, 1957). The model included CP
level, ME level, CP ME level interaction, BW block
and residual error, with effects tested by residual error.
When the CP ME level interaction was non-significant (P > 0.10), orthogonal contrasts were conducted
for linear and quadratic effects of level of ME. Initial
variable means were similar (P > 0.10) among treatments (Table 2) and initial values included as covari-
Table 2
Initial measures for growing Spanish wethers consuming ad libitum diets differing in concentrations of CP and ME
Item
Diet
10% CP,
2.00 Mcal/kg
ME
Age (days)
213
BW (kg)
17.5
Fleece weight (g)
168
Guard hair (g)
119
Cashmere (g)
48.9
% of total fleece
Guard hair
71.0
Cashmere
29.0
Cashmere diameter (mm) 15.38
SE
10% CP,
2.35 Mcal/kg
ME
10% CP,
2.70 Mcal/kg
ME
15% CP,
2.00 Mcal/kg
ME
15% CP,
2.35 Mcal/kg
ME
15% CP,
2.70 Mcal/kg
ME
210
19.6
166
126
39.8
204
21.1
158
116
42.6
211
20.5
166
127
39.5
210
18.0
171
117
54.6
211
17.5
163
118
45.7
75.7
24.3
14.73
73.3
26.7
15.35
76.4
23.6
15.14
67.4
32.6
15.68
73.9
26.1
15.52
2.0
1.37
11.5
10.5
8.35
6.48
4.58
0.434
136
D.S. Ivey et al. / Small Ruminant Research 35 (2000) 133±139
Table 3
Feed intake, ADG, feed conversion ratio and fleece characteristics for growing Spanish wethers consuming ad libitum diets differing in
concentrations of CP and ME for 84-days in the fall season
Item
% dietary CP
10
DM intake (g/day)
ME intake (Mcal/day)
ADG (g/day)
ADG:DM intake (g/kg)
Fleece weight (g)
Guard hair weight (g)
Cashmere fiber diameter (mm)
Cashmere fiber length (mm)
655
1.54
53.4
81
215
125
16.06
32.8
SE
P value
15
736
1.74
78.8
103
227
134
16.92
31.5
27.7
0.06
7.09
7.3
7.3
7.3
0.29
1.65
ates did not have signi®cant effects (P > 0.10), suggesting acceptable allocation to treatments.
3. Results
The CP ME level interaction was non-signi®cant
(P > 0.10) for DM intake, ADG and ADG : DM intake
(feed conversion ratio). DM intake was similar
(P > 0.10) among ME levels but greater (P < 0.05)
for 15% vs. 10% dietary CP (Table 3). Calculated ME
intake was greater (P < 0.01) for 15% CP than for 10%
and increased linearly (P < 0.01) with increasing dietary ME level, although numerically ME intake was
similar between 2.00 and 2.35 Mcal/kg ME diets.
ADG was greater (P < 0.02) for 15% vs. 10% dietary
CP and linearly increased (P < 0.10) as ME concentration in the diet increased, although numerically the
difference between the 2.35 and 2.70 Mcal/kg ME
diets was much greater than that between diets with
2.00 and 2.35 Mcal/kg ME. Feed conversion ratio was
greater (P < 0.04) for 15% CP than for 10% and
increased linearly (P < 0.02) as the concentration of
ME in the diet increased.
Total ¯eece weight was not in¯uenced (P > 0.10) by
dietary CP concentration; ¯eece weight increased
linearly (P < 0.03) as level of ME in the diet increased,
although numerically ¯eece weight was similar for
diets with 2.35 and 2.70 Mcal/kg ME (Table 3). Guard
hair weight was not affected (P > 0.10) by dietary
concentration of CP or ME. However, levels of CP and
ME in the diet interacted (P < 0.05) in the percentage
of cashmere in the total ¯eece and cashmere weight
(Figs. 1 and 2, respectively). These interactions
0.05
0.05
0.02
0.04
0.27
0.39
0.05
0.56
Dietary ME (Mcal/kg)
2.00
2.35
2.79
746
1.51
58.3
77
197
119
16.05
30.8
664
1.55
61.7
91
239
140
16.86
33.9
676
1.83
78.4
109
227
130
16.56
31.8
SE
34.0
0.08
8.69
8.9
8.9
9.0
0.36
2.02
P value
Linear
Quadratic
0.49
0.05
0.10
0.02
0.03
0.46
0.56
0.81
0.29
0.49
0.51
0.23
0.68
0.15
0.71
0.56
appeared primarily due to change in cashmere weight
as ME concentration increased with 15% CP diets,
since ME level had little effect with 10% dietary CP.
With 15% CP, cashmere weight increased markedly
then decreased slightly as ME level increased from
2.00 to 2.35 Mcal/kg and then to 2.70 Mcal/kg ME.
Cashmere weight was not affected by CP level with
the 2.70 Mcal/kg ME diet, but was lower for 15% vs.
10% CP with 2.00 Mcal/kg ME diets and greater with
diets containing 2.35 Mcal/kg ME. Cashmere diameter was greater (P < 0.05) for diets 15% in CP than
Fig. 1. The percentage cashmere in the total fleece for Spanish
wethers after consuming ad libitum diets with 10% or 15% CP and
2.00, 2.35 or 2.70 Mcal/kg ME (2.00, 2.35 and 2.70 ME,
respectively; SE ˆ 3.7) for 84 days in the fall season.
D.S. Ivey et al. / Small Ruminant Research 35 (2000) 133±139
Fig. 2. Cashmere weight for Spanish wethers after consuming diets
with 10% or 15% CP and 2.00, 2.35 or 2.70 Mcal/kg ME (2.00,
2.35 and 2.70 ME, respectively; SE ˆ 10.2) for 84 days in the fall
season.
for diets with 10% CP and was not in¯uenced by ME
concentration (P > 0.10). Cashmere length was not
affected (P > 0.10) by dietary treatments.
4. Discussion
Russel (1992) summarized that the plane of nutrition does not in¯uence cashmere ®ber growth when
nutrients provided exceed the requirement for BW
maintenance, with effects of nutrition on cashmere
®ber growth occurring only with severe nutrient
restriction. Differing intakes of protein or amino acids
(Johnson and Rowe, 1984; Ash and Norton, 1987a, b;
McGregor, 1988 or ME (McGregor, 1988; Norton
et al., 1990; KloÈren et al., 1993) above those required
for BW maintenance have not signi®cantly increased cashmere ®ber growth. However, as noted
earlier potential interactions between dietary protein
and ME levels have not been extensively studied
with ad libitum intake of diets differing in ingredient composition, as was tested in the present
experiment.
As noted previously, measures at trial initiation
were similar among treatments and not signi®cant
137
as covariates, which may be partially attributable to
the relatively low number of observations per treatment and high variability in some measures such as
cashmere ®ber weight. However, numerical differences among treatments in initial cashmere ®ber
weight resembled those at the end of the experiment.
Thus, it is possible that with a greater number of
animals, initial cashmere weight would have signi®cantly in¯uenced cashmere ®ber weight at the end of
the experiment and, thus, use as a covariate would
have lessened or eliminated observed treatment differences in ®nal weight. Relatedly, it was not possible
to obtain initial measure information soon enough for
use to allot animals to treatments, as conducted by
Restall et al. (1994). This alternate method of allocation also may have in¯uenced treatment effects.
Hence, future experimentation concerning nutritional
plane effects on cashmere ®ber growth should entail
usage of a greater number of animals per treatment
and (or) treatment allotment based on inherent differences among animals in cashmere ®ber growth.
Although, it should be noted that such procedures
will not eliminate such problems. For example, variation among animals in seasonal changes in follicle
activity might not be re¯ected by earlier cashmere
®ber growth.
Nutritional planes in the present experiment were
greater than required for BW maintenance, as evidenced by observed ADG. Hence, treatment differences in cashmere ®ber weight are not clearly in
agreement or disagreement with the summarization
of Russel (1992), regarding no effects of nutritional
planes above maintenance, although the effect of
dietary CP level on cashmere ®ber diameter is notable.
However, results of the present experiment do suggest
the need for further study of such effects with US
Spanish goats selected for cashmere ®ber growth,
particularly as relating to potential for interactions
between dietary energy and protein levels. For
example, a plausible framework of logic for the
observed interaction in cashmere ®ber production
relating to use of nutrients by different tissues can
be put forward.
With the 2.00 Mcal/kg ME diet, 15% CP may have
increased amino acid catabolism for energy compared
with 10% CP, thereby minimizing amino acids available for peripheral muscle protein accretion. Similarly, greater DM intake and ADG for 15% vs. 10% CP
138
D.S. Ivey et al. / Small Ruminant Research 35 (2000) 133±139
diets indicates greater nutrient absorption and hormonally controlled nutrient partitioning for nutrient
use by peripheral muscle. Amino acid catabolism for
energy with 15% dietary CP should have been less
with the 2.35 vs. 2.00 Mcal/kg ME diet due to greater
microbial protein synthesis from increased ruminal
OM fermentation. This would have increased the
proportion of the added supply of absorbed amino
acids available for use in protein synthesis from 15%
dietary CP relative to that for 10% with 2.35 Mcal/
kg ME. These factors imply a greater quantity of
amino acids available for support of ®ber growth with
2.35 Mcal/kg ME and 15% vs. 10% dietary CP,
depending on use in peripheral muscle accretion. In
this regard, although ADG linearly increased with
increasing dietary ME concentration, numerically
ADG was similar for 2.00 and 2.35 Mcal/kg ME
diets. An explanation for numerically similar ADG
for 2.00 and 2.35 Mcal/kg ME diets is not readily
apparent. However, nutrient partitioning among
various tissues does not necessarily change linearly
as diet composition is varied. Relatedly, the proportion
of energy used by visceral tissues in¯uences the
quantity of energy available for use by non-visceral
tissues. Visceral tissue energy use relative to absorbed
energy is greater for forage- than for concentratebased diets, but the pattern of change as dietary
concentrate level increases has not been explored
(Goetsch, 1998). Much greater ADG for diets with
2.70 Mcal/kg ME compared with diets lower in ME
could re¯ect a relatively high proportion of absorbed
amino acids added by use of 15% vs. 10% CP being
accreted in peripheral muscle, thereby preventing
effect of dietary CP concentration on cashmere production.
5. Conclusions
With growing Spanish wethers in the fall season and
ad libitum consumption of diets approximately 40%,
60% and 80% concentrate, corresponding to 2.00, 2.35
and 2.70 Mcal/kg ME, respectively, cashmere ®ber
diameter was greater for 15% vs. 10% dietary CP
regardless of ME level. Diet composition did not
impact cashmere ®ber length. Dietary concentrations
of CP and ME did not alter guard hair weight but
interacted in weight of cashmere ®ber. However,
similar numerical differences, although of lesser magnitude, among treatments in pre-experiment cashmere
®ber weight existed, suggesting need for further
experimentation with greater animal numbers and
(or) treatment allotment based on animal differences
in most important variables.
Acknowledgements
This research was partially supported by USDA
Grant No. 91-38814-6241.
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