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Protein and sulphur amino acid nutrition of hair fibre-producing
Angora and Cashmere goats
*
H. Galbraith
Department of Agriculture, University of Aberdeen, 581 King Street, Aberdeen, AB24 5UA, UK
Abstract
The results from a number of studies are presented which investigated responses in fibre production of British Cashmere and Angora goats to variation in protein and sulphur amino acid nutrition under conditions of active fibre growth. Requirements for amino acids were considered in the context of the concentration of amino acids, including cysteine and methionine, in rumen microbial protein and in dietary protein supplements compared with the amino acid composition of hair fibre. Increases in fibre yield and diameter were consistently observed in Angora goats given good quality protein
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supplements or rumen-protected intestinally-available methionine (SmartamineEM, Rhone-Poulenc). Cashmere yield was not influenced by urea or white fishmeal supplementation but responded positively (in contrast to other studies in the literature) to additional dietary methionine. While responses in cashmere production have been recorded in response to protein supplementation at sub-maintenance levels of nutrition, it is suggested that one component of the absent or reduced response at above maintenance may be the smaller quantitative synthesis of this fibre compared with mohair production by Angora goats. The results are considered in the context of studies from the sheep literature in which protein and amino acid supplementation were shown to stimulate proliferation of hair forming cells in the wool follicle and to increase deposition of protein fractions containing high concentrations of sulphur-containing amino acids. Results from an in vitro study suggested that methionine could support cashmere fibre growth (approximately 0.75) in the absence of cysteine and cystine, providing evidence that methionine is essential for fibre production and that transulphuration occurs in isolated hair follicles. However, cysteine and cystine were also required to produce maximum growth. In the context of competition between the hair follicle and other body tissues, data are presented which illustrate the increases in nitrogen retention and / or anabolic growth response to protein or protected-methionine supplementation in non-integumental tissues of Cashmere and Angora goats also, despite the presence of lower concentrations of sulphur-containing amino acids in these tissues. The results confirm the value of a good quality protein supplement or more targeted supply of rumen-protected intestinally-available methionine to correct a frequently apparent deficiency in sulphur amino acid supply for (a) growth of hair fibre by Angora goats and, less consistently, by Cashmere goats and (b) other body tissues in both genotypes.
´ ´ Resume
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Les besoins en aminoacides ont ete raisonnes a partir de la concentration des aminoacides, y compris cysteine et
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methionine dans les proteines microbiennes du rumen et dans les apports alimentaires de proteines par rapport a la
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composition en aminoacides de la fibre de poils. Si on a fourni des supplements de proteines de bonne qualite ou de
*Fax: 144-1224-273-731.
E-mail address: [email protected] (H. Galbraith)
TM
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methionine protegee dans le rumen et disponible dans l’intestin (Smartamine M, Rhone Poulenc), des augmentations du
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rendement et du diametre des fibres ont ete generalement observees. Le rendement en Cachemire a ete influence seulement
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par les supplements en methionine, ce qui peut indiquer une synthese plus faible de cette fibre par rapport a la production de
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Mohair. Les resultats ont ete compares a ceux des etudes sur moutons qui ont montre que la proteine et les supplements
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d’acides amines activent la proliferation des cellules capillaires dans les follicules et augmentent la synthese des proteines de
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la laine qui contient des concentrations fortes des amino-acides soufres. Les resultats d’une etude in vitro ont suggere que la
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methionine pourrait favoriser la poussee de fibre (a peu pres 0.75) en l’absence de cysteine et cystine. Ces resultats seraient
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un argument pour une transulphurisation dans les follicules des poils isoles. Cependant, la cysteine et le cystine sont
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necessaires pour produire une pousse maximale. Des donnees presentees montraient une reponse anabolique a l’addition de
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proteines et de methionine protegee dans des tissus non-tegumentaux malgre la presence de concentrations plus faibles en
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amino-acides soufres dans ces tissus. Les resultats confirment la valeur d’un supplement d’une proteine de bonne qualite ou
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d’un approvisionnement mieux raisonne en methionine protegee dans le rumen et disponible dans l’intestin pour compenser
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un manque frequent d’aminoacides pour la poussee de fibres de cheveu et la croissance des autres tissus chez les chevres Angora et Cachemire. 2000 Elsevier Science B.V. All rights reserved.
Keywords: Protein; Sulphur amino acids; Methionine; Hair fibre; Cashmere; Angora goats
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1.2. Characteristics of caprine hair fibre and 20 or greater in the high sulphur cysteine-rich
amino acid composition of hair, body tissues and fraction of the matrix proteins.
protein supplements Overall concentrations of cysteine (including that present in its dimer form cystine) for mohair and The major goat fibre products are mohair produced sheep wool in comparison with muscle and sources by the essentially single-coated genetically-distinct of dietary supply are shown in Table 1. The main Angora goat and cashmere which is produced by the points to note are the greater concentrations of more genetically heterogeneous double-coated Cas- cysteine in mohair and wool than muscle, rumen hmere goat. Both fibre types are produced by sec- microbial protein and the examples of dietary protein ondary hair follicles. Mohair fibres are lustrous, non- supplements, soya bean meal and white fishmeal medullated, grow at up to 2.5 cm / month and range (Galbraith, 1998). The supply of sulphur amino acids in diameter from 22 to 45 mm, with annual greasy above that supplied by microbial protein also de-fleece yields of up to 6 kg. Cashmere, which is the pends on the digestibility of the rumen-undegraded fine undercoat, grows at up to 1.5 cm / month, fraction of the dietary supplement.
although frequently less, with commercially accept-able diameter in the range of 12–18mm, and yields
of 50–600 g / year. Growth of cashmere, unlike 2. Responses to dietary protein supplements
mohair, is dependent on photoperiod. Guard hair, the
coarse overcoat of the Cashmere goat is produced by 2.1. Response of Angora goats to variations in primary follicles and also grows seasonally with dietary protein and energy
diameters in the range 30–90mm with length 4–20
cm and yields up to 500 g / year. The commercial The effect of two levels of dietary protein and value of cashmere and Angora fibre products is energy (see Table 2) was studied for 112 days in 24 optimised by high yields, small diameters and ab- Australasian-type yearling castrate male Angora sence of primary fibres and other contaminants. goats weighing |22 kg (Shahjalal et al., 1992).
Hair is produced by follicles situated in the skin of Protein supplementation was provided by a mixture animals. The hair product is composed largely of of equal quantities of white fish meal and soya bean cells of the cortex which contain large amounts of meal to give estimated concentrations (g / kg dry intermediate filament proteins (IFPs) (including matter, DM) for rumen undegradable protein (UDP) keratins) and a non-filamentous matrix containing of 26 (LP) and 79 (HP) and for rumen degradable intermediate filament-associated proteins (IFAPs). protein (RDP) 82 (LP) and 101 (HP), respectively. The IFPs are considered to contain concentrations of Positive responses in mid-side raw fibre yield, to the the sulphur amino acid cysteine (residues per 100 increase in dietary crude protein concentration from residues of amino acids) of approximately 6.0 with 108 to 180 g / kg DM, occurred in the first 4 weeks
Table 1
Relative composition of selected amino acids, (g amino acid / 16 g N) in tissues and dietary protein sources (modified from Souri et al., 1997 and Galbraith, 1995)
Amino Mohair Wool Muscle Rumen Extracted White
acid microbial soyabean fishmeal
protein meal
Threonine 5.9 5.5 3.9 5.2 4.2 4.2
Leucine 8.6 6.5 5.8 7.4 8.2 6.7
Phenylalanine 3.6 4.6 3.1 5.5 5.5 3.9
Lysine 2.9 3.5 5.9 8.1 6.8 5.7
Methionine 0.4 0.6 1.8 2.5 1.4 3.0
Table 2
Raw yield and diameter of mid-side mohair fibre of Angora goats given diets containing (per kg DM) 10.0 MJ (LE) or 11.9 MJ (HE) and 108 g (LP) or 180 g (HP) crude protein (modified from Shahjalal et al., 1992)
a
Raw fibre yield Treatments Significance of contrast
2
(g / 100 cm )
LE–LP LE–HP HE–LP HE–HP SED P E
Period of treatment (weeks)
1–4 1.68 2.49 1.65 2.11 0.357 * NS
5–8 2.88 3.97 3.05 3.53 0.335 ** NS
9–12 2.50 3.74 3.19 3.75 0.319 ** NS
13–16 1.74 3.14 2.59 3.31 0.279 *** **
1–16 8.91 13.3 10.5 12.7 1.08 *** NS
Fibre diameter (mm) 29.9 35.6 32.4 35.8 1.49 *** NS
(day 112)
a
P, protein; E, energy (no significant interaction effects were recorded); *P,0.05, **P,0.01, ***P,0.001.
and were maintained throughout. There was no follicles for supplementary nutrients are shown in significant response to energy until the final 3 weeks. Table 3. On average, the higher supply of dietary These data confirm earlier reports (e.g. Shelton and energy increased live weight gain (LWG), efficiency Huston, 1966; Deaville and Galbraith, 1992; Sahlu et of food conversion, empty (digesta-free) body weight al., 1992; Reis and Sahlu, 1994) which suggested and weights of chilled carcass and dry matter, crude that growth of mohair may be limited by inadequate protein, lipid and ash in bone-free dissected carcass supply of protein in the diet and that protein supple- tissue. All of these parameters were improved by the mentation stimulated yield but produced commercial- dietary protein supplementation. In addition, the ly undesirable increases in fibre diameter. presence of statistically significant interactions be-The effect of variations in dietary protein and tween dietary protein and energy suggested that energy on growth and carcass and body components responses to (a) protein supplementation were great-which would be expected to compete with hair est on the low energy diet and to (b) energy
Table 3
Growth performance and selected carcass characteristics of Angora goats given diets containing (per kg DM) 10.2 MJ (LE) or 11.9 MJ (HE) and 108 (LP) or 180 g (HP) crude protein (modified from Shahjalal et al., 1992)
a
Treatments Significance of contrasts
LE–LP LE–HP HE–LP HE–HP SED P E I
Live-weight gain 48 80 91 116 7.26 ** **
(LWG, g / day)
Food conversion efficiency 0.062 0.099 0.117 0.139 0.0078 *** *** (LWG / DMI)
Empty body weight 23.5 28.5 29.0 31.3 0.821 *** *** *
(EBW, kg)
Gut contents (kg) 3.83 4.16 2.99 3.71 0.344 * * *
Chilled carcass weight 12.1 15.3 15.2 16.8 0.507 *** *** *
(CCW, kg)
Weight of carcass (kg)
Dry matter 2.16 2.89 3.06 3.32 0.163 *** ***
Crude protein 0.697 0.867 0.877 0.967 0.051 ** **
Lipid 1.18 1.82 2.00 2.13 0.130 ** *** *
Ash 0.035 0.045 0.044 0.049 0.0032 ** *
a
supplementation were greatest on the low protein 82.3, respectively. The data were examined by diet. These results contrast with these for hair growth analysis of variance and the significance of linear (L) (Table 2) where consistent responses were obtained quadratic (Q) and cubic (not shown) relationships only for dietary protein supplementation and where between treatments determined. There were no ef-statistically significant interactions were not ob- fects of dietary treatment on the intakes of dry matter tained. The results are also seen to contrast with or estimated metabolisable energy. As planned, those reported by Sahlu et al. (1992) in which intakes of crude protein increased linearly according
21
increases in crude protein, (up to 190 g kg ) in to concentration present in each diet.
isoenergetic diets resulted in greater yields of both The clean fibre yield was significantly affected (Q; raw and clean fibre, but had no effect on body P,0.05) between day 1 and 56 with increases up to
21
weight gain of 18-month-old female Angora goats. 165 g kg DM and a decrease at the highest 21
The reasons for the differences in response are not concentration of 185 g kg DM. Fibre diameter clear, but may relate to differences in sex (i.e. increased linearly (L; P,0.05) as the protein intake castrate males versus females) and the potential for was raised. The data indicate that a concentration of
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growth. 165 g kg DM may be most appropriate for
optimising fibre yield, but not diameter, the lowest 2.2. Optimisation of dietary protein concentration value for which was recorded on the diet providing
for mohair fibre production least dietary crude protein in the present study. In view of the apparently positive relationships between The question of optimising dietary protein con- fibre yield and diameter, decisions on the most centration to balance benefits in fibre yield against economic concentrations of dietary protein will increases in diameter such as these demonstrated in depend on the balance between the relative values of Table 2 was investigated in a further study (Shahjalal the weight and fineness of fibre produced where et al., 1991) (Table 4). In this 63-day study, 20 control of protein nutrition can be achieved. Similar Australasian type male castrate Angora goats, aged studies designed to determine the requirements for about 16 months and weighing 28 kg on average dietary nutrients for cashmere goats have been were offered diets containing an estimated 9.6 MJ conducted under Australian conditions by, for
exam-21
kg DM metabolisable energy at intakes of 55 g ple, Ash and Norton, 1987a,b; McGregor, 1988 and
0.75
DM / kg LW with variations in crude protein (CP) Kloren et al., 1993a,b. Variables measured included achieved by replacing dietary sugar beet pulp with a effects of dietary protein and energy in addition to mixture of soya bean meal and fish meal. Estimated age and sex of goat, pregnancy, lactation and dy-dietary rumen degradable and undegradable protein namic changes in photoperiod. Of particular
impor-21
(g kg DM) ranged from 74.5 to 103 and 27.5 to tance is the description of responses to protein
Table 4
Mid-side clean fibre yields, intakes of dietary dry matter, crude protein and estimated metabolizable energy, and fibre diameter of Angora goats given diets differing in crude protein concentration (modified from Shahjalal et al., 1991)
a
Treatment means Statistical
b
Dietary crude protein (g / kg DM) significance
102 126 165 185 SED L Q
Dry matter intake (kg) 44.1 38.2 42.9 41.0 2.30 NS NS
Crude protein intake (kg) 4.16 4.84 7.08 7.57 0.33 * NS
Est. ME intake (MJ) 395 364 410 410 22.2 NS NS
Data have been adjusted for initial fibre yield (day 0) as covariate.
b
supplementation only under conditions of sub- usually not limited by protein nutrition. There is, in maintenance levels of nutrition (e.g. McGregor, contrast, evidence for increases in guard hair
pro-1988). duction following improved dietary nutrient supply
(see Russel, 1995). 2.3. Effect of nitrogen source on cashmere
production 2.4. Effect of protein nutrition on cellular
characteristics of wool hair follicles
Cashmere is an economically more valuable fibre
than mohair and there is considerable interest in Hair follicles arise as a result of the proliferation means of improving yield. The effect of protein of cortical and associated cells of the follicle bulb nutrition was therefore studied in 24 male castrate and cortical cell differentiation to form the hair shaft. Cashmere goats (12 Siberian (S)3Irish feral and 12 These processes have not yet been quantitatively Australian (A)3Irish feral) in a 102-day study described for caprine hair follicles. However, some (Galbraith et al., 1994). Within genotypes the goats indication of cellular events may be obtained from were allocated to receive nitrogen supplementation the study of Hynd (1989) which investigated protein either based on urea1sodium sulphate (U) or white supplementation of sheep which are considered to fish meal (F) to give estimated concentrations respond similarly to Angora goats (Russel, 1995). In
21
(g kg DM) of RDP and UDP of 86 and 64 and this study the effect of alterations in protein nutrition 117 and 32 for diets F and U, respectively, with an on wool follicle cell kinetics was determined using
21
estimated ME concentration of 11.0 MJ kg DM Merino and Corriedale breeds. The sheep, aged 3 for the basal diet. Mid-side total fleece growth years, were offered diets containing 15 g N and 9.1 measurements indicated no significant effects due to MJ metabolisable energy (ME) per kg DM at a protein supplementation (Table 5, selected data maintenance level for 9 weeks, followed by an 8-shown) with no significant alteration in the pro- week period of supra-maintenance feeding of a diet portions by weight of guard hair to cashmere. There containing an estimated 51 g N and 10 MJ ME per were similarly no effects of source of protein supple- kg DM and designed to provide 6 g per day of ment on the average diameter of cashmere fibres. cystine for post-ruminal absorption. Measurements These results confirm others in the literature as of clean wool growth were made over the last 3 reviewed, for example, by Restall et al. (1994), weeks and other fibre and hair follicle characteristics Russel (1995) and Souri et al. (1998a) that (a) under were studied for the final 7 days of each feeding these or similar conditions, and above maintenance period. Selected results are shown in Table 6. The levels of nutrition and (b) unlike mohair production change from the low protein to the higher protein by Angora goats (see Table 2), cashmere growth is diet resulted in a significant increase in the rate of
Table 5
Nutrient intake, mid-side fleece growth (cashmere1guard hair), day 49–97, proportion of cashmere and guard hair and fibre diameter of Siberian (S) and Australian (A) cross Irish feral goats given dietary supplements of urea (U) or white fishmeal (F) (modified from Galbraith et al., 1994)
Treatments
SU SF AU AF SED
Dry matter intake (kg) 74.2 76.4 76.3 74.9 10.4
Crude protein intake (kg) 11.1 11.5 11.4 11.2 1.53
Est. ME intake (MJ) 767 798 782 787 105
2
Mid-side growth (g / 100 cm ) 0.93 1.26 1.31 1.19 0.58
Day 97
Guard hair 0.65 0.73 0.87 0.77 0.14
Cashmere 0.35 0.27 0.13 0.23 0.14
Table 6
Mean values (with S.D.) for fleece, fibre, wool follicle and cellular characteristics of sheep offered diets containing either 15 (low) or 51 (high) g N / kg DM (see text for details: modified from Hynd, 1989)
N in Fleece Fibre Fibre Cortex Total no. No. of No. of
diet growth diameter length volume of bulb mitoses cortex cells
21 23 3 21 21 21
(g N kg ) (g / day) (mm) (mm / day) (10 3 mm h ) cells h produced h
15 10.5 25.3 378 7.4 909 26 8.0
S.D. 1.8 2.5 30 1.7 221 4.7 1.4
51 14.0 27.2 475 11.0 1177 35 11.3
S.D. 2.9 3.5 44 3.2 309 7.0 2.8
wool production associated with increases in the periods, whereas responses to cashmere were ob-germinative volume of the bulb, rates of fibre tained from days 31–58 only. These responses of elongation and proliferation of cells of the bulb. This increasing yield without affecting diameter indicate latter response is of particular interest since it implies greater growth due to an enhanced rate of elongation a direct local effect of nutrition supply on the for the cashmere fibre. Guard hair was not affected mechanisms responsible for cell division, including by supplementation. The presence of significant those at the level of the gene and / or an indirect interactions indicates the generally greater response effect involving stimuli perhaps of systemic hormon- of Angora goats to supplementation. However, the al or more local paracrine origin. It may be con- positive response for cashmere production contrasts cluded from these results that the effects of improved with the report by Ash and Norton (1987a) who protein nutrients are more complex than those pro- observed no response in cashmere growth to dietary duced solely as a consequence of improved amino supplements of methionine in 3–4-year-old Aus-acid supply for protein synthesis in the proliferating tralian Cashmere entire males (live weights were not and differentiating cortical cells which form the hair reported and when differences in total hair growth
fibre. were attributed to an increased production of guard
hair by primary follicles). This latter result for cashmere is consistent with the absence of response
3. Responses to rumen-protected methionine to improved protein supply at supra-maintenance levels of nutrition already discussed in Section 2.3. A 3.1. Response of Angora and Cashmere goats to possible explanation made by Ash and Norton
rumen-protected methionine supplementation (1987a) is that the genetic potential for cashmere production had already been met in the absence of One disadvantage of meeting the requirement for supplementation by the low-yielding animals used in one amino acid by means of protein supplementation their study. They also suggest, in the absence of is the over-provision of other amino acids, the increases in blood cysteine / cystine concentrations, disposal of which places a metabolic burden on the that methionine did not readily promote the pro-animal. With this in mind, we have studied the duction of cysteine by transulphuration in the liver response of both Cashmere and Angora 1-year-old and kidney, but this did not appear to inhibit the goats with initial average live weights of 52.5 and anabolic response of guard hair. This observation 47.5 kg, respectively to supplementation with rumen- may be considered in the context of subsequent protected intestinally-available methionine studies (see Section 3.3) which suggested the
pres-ˆ
(SmartamineEM, Rhone-Poulenc, Paris, France). At ence of transulphuration in the secondary hair follicle inclusion rates of 2.5 g / day, in addition to a basal of the cashmere goats.
Table 7
2
Mid-side fibre yields (mg / 100 cm / day), proportion of cashmere and guard hair and diameter of cashmere and mohair in response to methionine supplementation (modified from Souri et al., 1998a)
a b
Treatment groups Significance of contrasts
CO CS AO AS s.e. D G I
Days 0–30
Total raw fibre yield 42.0 53.0 96.3 141 8.0 ** ***
Guard hair yield 29.0 33.0 2.4
Cashmere yield 13.0 19.0 1.7
Proportion 0.31 0.37 0.02
Diameter (day 30) (mm) 19.7 19.2 27.6 32.9 1.9 *** *** ***
Days 31–58
Total raw fibre yield 46.0 54.0 87.0 156 7.0 *** *** **
Guard hair 33.0 35.0 2.9
Cashmere 12.0 19.0 1.5 *
Proportion 0.27 0.35 0.02 *
Diameter (mm) (day 58) 18.9 19.7 28.3 32.6 1.7 *** *** ***
a
C, Cashmere; A, Angora; O, no supplementation; S, methionine supplementation.
b
Contrast: D, diet; G, genotype; I, interaction between diet and genotype.
production in that the responses to methionine (an g / day with |1.5 g / day attributable to cashmere in
amino acid frequently deficient in ruminant diets e.g. which a methionine response was obtained in the (Orskov, 1992) were positively related to the nutrient study of Souri et al. (1998a). The goats in the latter demands for synthesis of protein deposited in the study were derived from a commercial Scottish fibre produced. For example, it is clear from the data Cashmere breeding programme which included shown in Table 7 that under similar conditions of selection for yield and although the average diame-husbandry and nutrition (a) the response to ters of cashmere fibres exceeded the commercially methionine was larger and (b) this was associated desirable value of 18mm, they were well within the with a greater total fibre production by Angora goats range for cashmere of 8–24mm as described by Ash
2
than Cashmere goats (e.g. 156 vs. 54 mg / 100 cm / and Norton (1987a).
day on methionine supplemented diets) and that the The effects of rumen-protected methionine supple-weights of secondary follicle fibre production by mentation on growth and nitrogen retention in addi-Angora goats was eight to ten times greater. It is also tion to hair fibre characteristics were also studied in suggested that the response in cashmere production these animals. Results are presented for the first 40 in this study was due at least partially to an in- days of the study (Table 8). These showed signifi-adequate supply of methionine / cysteine from the cant positive responses to supplementation for LW unsupplemented diets to meet the maximum potential gain, food conversion efficiency and nitrogen
re-0.75 )
for cashmere growth by the genotype studied. Differ- tention (both mg / kg LW and g / kg N intake per ences in response compared with other reports in the day). The results suggest that methionine supple-literature may reflect differences in the potential of mentation acted also to overcome limitations in different genotypes of goats to produce cashmere growth of non-fleece tissues for both genotypes. (e.g. Bishop, 1994 and Restall et al., 1994) and the Although statistical significance of a genotype3diet degree of deficiency of the absorbed amino acid or interaction was not obtained, there was a marked metabolites in relation to the requirement for maxi- trend towards a greater response by Angora goats mum fibre growth. For example, the protein accre- which did attain significance from day 40–68 of the tion in fleece in the study of Ash and Norton (1987a) study. These animals also exhibited a significantly is reported at 0.3 g / day with |0.1 g / day due to greater retention of N than Cashmere goats,
Table 8
Growth, digestive and nitrogen balance characteristics of Cashmere and Angora goats, in response to methionine supplementation (day 0–40) (modified from Souri et al., 1998a)
a
Live-weight gain (LWG, g / day) 49.7 74.4 44.7 64.1 8.91 *
Faecal-N excretion (g / day) 6.12 6.2 5.7 5.7 0.21
Urinary-N excretion (g / day) 7.5 7.6 6.0 4.7 0.42
N retention *
C, Cashmere; A, Angora; O, no supplementation; S, methionine supplementation.
b
Contrast: D, diet, G, genotype, Interactions between diet and genotype did not attain significance.
there appears to be no other report in the literature relative partitioning was unchanged in response to describing such responses in body and N retention to improved supply. This represents an interesting dietary methionine, evidence for response to im- conclusion given the disproportionately high con-proved protein nutrition in Australian Cashmeres has centration of cysteine / cystine in hair fibre (see Table been described, for example, by Johnson and Rowe 1).
(1984) and Ash and Norton (1987a). These latter
workers demonstrated significant increases in the 3.2. Effect of sulphur amino acid supplementation daily gain of nitrogen (in addition to empty body on the composition of hair protein.
weight, water, fat and ash) in response to increases in
dietary crude protein concentration from 113 to 163 While it is clear that responses to protein and 21
and 209 g kg . That these responses did not methionine supplementation produce superior yields produce significant effects on final empty body particularly of mohair and sheep wool there is little weight and chemical composition as a proportion of systematic information on the proteins which com-empty body weight was attributed to the extensive prise the major components of the hair fibre and how ruminal degradation of the crude protein and only they might be altered by increased deposition in the small differences in protein / amino acids available follicle. Gillespie (1991) has demonstrated the simi-for uptake at the small intestine. The use of the larity of protein fractions in the products of a number rumen-protected intestinally-available product essen- of different ‘keratinised’ integumental tissues includ-tially improves delivery of absorbable methionine at ing hair from different sources, hoof horn and human the small intestine and the results shown in Tables 7 finger nails. In the absence of specific studies on goat and 8 indicate the presence of response to a dietary hair production, it is useful to consider the responses deficiency of this amino acid. in sheep wool to increased sulphur amino acid In another study Souri et al. (1997), showed that supply. In the study described by Gillespie (1991), 10-month-old Angora goats given basal diets con- sheep were infused abomasally with sulphur-con-taining |100 g crude protein per kg DM and taining amino acids (methionine, cysteine) or
Table 9
Amino acid composition (residues / 100 residues) of sheep wool and its constituent high sulphur proteins before (BS) and after (AS) sulphur enrichment (modified from Gillespie, 1991)
residues per cent of cysteine (measured as S-car- question was tested in vitro (Souri et al., 1996) using boxymethyl-cysteine). This fraction has been as- our follicle explant system (Ibraheem et al., 1994). cribed importance in the formation of the inter- Small skin samples were obtained by approved mediate filament–matrix complex, and in the pro- technique from the mid-side area of three 18-month-duction of cystinyl (disulphide) bonds associated old, Scottish male castrate Cashmere goats in the with properties of strength and elasticity of the hair time period August to September. Anagen cashmere fibre. The increased diameter of mohair fibres fol- follicles were isolated and incubated (|90 /
treat-lowing methionine supplementation is in keeping ment) in Williams E medium without cystine, cys-with the suggested role of an increased intermediate teine or methionine (O) and then supplemented to filament-associated protein fraction in producing a give final concentrations as follows: 100 mM greater volume of cells of the hair cortex. Recent methionine1330 mM cysteine183 mM cystine studies (Galbraith et al., 1998) have described the (MC); 100 mM methionine without cysteine or effect of rumen-protected methionine supple- cystine (M): 330 mM cysteine183 mM cystine mentation in increasing growth rate and cysteine without methionine (C).
deposition in hair and claw horn of Angora goats. It The results (Table 10) indicated that the follicles is interesting to note that the hardness of claw horn in treatment MC (containing all of the sulphur amino from methionine-supplemented animals measured by acids) exhibited typical hair growth rates for up to duropenetrometer was greater than that of unsup- 120 h incubation. Follicle growth and viability at 72
plemented controls. h was significantly reduced in the absence of
methionine with cystine and cysteine present (treat-3.3. Effect of methionine and cysteine on hair fibre ment C). In addition, methionine supported growth
growth and viability in vitro of follicles in the absence of cysteine and cystine to about 0.75 of that recorded in its presence. It is The results in the studies described above did not concluded that methionine is essential to support hair explain the relative importance of methionine and growth and viability and that cysteine / cystine are not cysteine for hair growth or address the issue of essential provided that methionine is present. The transulphuration (studied in sheep wool, e.g. by results also provide strong evidence for the presence Downes et al. (1964) and alluded to by Ash and of a transulphuration pathway within the cashmere Norton (1987a)) in the lack response of Cashmere secondary hair follicle.
Table 10 absence of more definite information, the anagen Elongation (mm) and number of viable (V) anagen cashmere hair cashmere hair follicle appears to be similar to that of follicles in 24-h growing periods in vitro (modified from Souri et
sheep wool or mohair follicles apart from having a al., 1996)
reduced capacity to grow hair. Comparisons of
a,b
Treatments P.S.D
differences in the capacity to grow hair were made in
CM M C O the in vitro studies of Lee et al. (1994). These
a a b b workers compared secondary follicle characteristics
24 0.11 0.09 0.05 0.03 0.07
a a a a
V 89 70 54 41 9.6 of entire male Siberian Cashmere goats with male
a b c c castrate Angoras and demonstrated under similar
48 0.11 0.08 0.04 0.03 0.06
a a a a
V 83 58 26 25 10.0 conditions that the mohair follicle produced a
4.9-a b c c times greater volume of fibre, exhibited a 4.6-times
72 0.13 0.09 0.02 0.02 0.07
a a b b greater concentration of DNA, had a 7.6-times
V 62 42 9 2 6.0
14
a a greater uptake of U- C-labelled leucine per follicle
120 0.12 0.10 0.00 0.00 0.07
a a and deposited 1.6-times more protein per mg DNA.
V 54 38 0 0 7.4
These results suggest that the mohair follicle had
a,b
Values are means with pooled standard deviation (P.S.D).
more cells than cashmere in addition to an intrinsi-Values in the same row with different superscripts are significantly
cally greater capacity for protein synthesis per cell. It different (P,0.05). See text for treatments.
is logical, therefore, to conclude that one component of a failure to respond to improved sulphur amino mohair follicles. These results suggest that actively acid nutrition by increasing cashmere production is growing anagen cashmere and mohair secondary that the requirement is already met and that there is follicles are at least partially independent of the an absence of deficiency for these nutrients. Other synthesis of cysteine / cystine in, and supply from, factors controlled by genotype or nutrition may thus other tissues. However, the studies do suggest that be expected to limit cashmere production as sug-maximum hair follicle growth requires the presence gested by Johnson and Rowe (1984).
of methionine and cysteine / cystine. Pierzynowski et It may also be concluded that where a response al. (1997) have also demonstrated that administration occurs such as under sub-maintenance nutrition or as of a mixture of dipeptides (methionine–leucine and shown in Table 7 above, the provision of methionine cystine–leucine) to a perfused area of skin of Angora overcomes a limitation imposed by sulphur amino goats increased the production of mohair compared acid deficiency.
with an infusion of saline. This effect was associated with altered concentrations of amino acids in venous
blood. The authors suggested that the dipeptide 4. Conclusions
infusion increased the uptake of amino acids for
protein synthesis. The amino acid composition of the growing hair
cas-for cashmere goats. In: Laker, J.P., Bishop, S.C. (Eds.), Genetic hmere yield response to a protected methionine
Improvement of Fine Fibre Producing Animal. European Fine product. Yields of mohair are considerably greater
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production (Boar goat). S. Afr. J. Anim. Sci. 22, 143–148. sulphur amino acid supplementation. Both Cashmere
Deaville, E.R., Galbraith, H., 1992. Effect of dietary protein level and Angora genotypes respond to improved protein and yeast culture on growth, blood prolactin and mohair fibre and sulphur amino acid nutrition by variously in- characteristics of British Angora Goats. Anim. Fd. Sci.
Tech-nol. 38, 123–133. creasing growth rate, carcass weight and protein
Downes, A.M., Sharry, L.F., Till, A.R., 1964. The fate of deposition and nitrogen retention. Responses in hair
intradermal doses of labelled amino acids in sheep. Aust. J. follicle growth, considered in the context of studies Biol. Sci 17, 945–959.
in sheep, show that an improved supply of protein Galbraith, H., Mengal, M.A., Scaife, J.R., 1998. Effect of dietary and / or sulphur amino acids may stimulate the prolif- methionine and biotin supplementation on growth and protein and amino acid composition of caprine hoof horn. In: Lischer, eration of cortical cells in the follicle and wool
C.H.J., Ossent, P. (Eds.), 10th Int. Symp on Lameness in growth and deposition particularly of high sulphur
Ruminants. University of Zurich, Switzerland, pp. 227–229. amino acid-containing proteins. Measurements made Galbraith, H., Shahjalal, M.D., Topps, J.H., 1994. The effect of on isolated anagen secondary hair follicles in vitro dietary supplements based on urea or white fish meal on demonstrated the essential requirement for growth and fleece characteristics of Siberian and Australasian
crossbred Cashmere goats. Anim. Prod. 58, 482. methionine, although not cysteine for growth and
Galbraith, H., 1995. The effects of diet on nutrient partition in viability of cashmere. The response to the
rumen-Scottish cashmere and Angora goats. In: Laker, J.P., Russel, protected intestinally-available methionine product A.J.F. (Eds.), Nutrition and Grazing Ecology of Speciality confirms the value of a targeted supplement which Fibre Producing Animals, Vol. European Fine Fibre Network supplies an otherwise potentially deficient amino Occasional Publication no.3, Macaulay Land Use Research
Institute, Aberdeen, pp. 23–50. acid without providing additional amino acids in
Galbraith, H., 1998. Nutritional and hormonal regulation hair quantities above those required by the animal.
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Gillespie, J.M., 1991. The structural proteins of hair. Isolation, characterisation and regulation of biosynthesis. In: Goldsmith,
Acknowledgements
L.A. (Ed.), Physiology, Biochemistry and Molecular Biology of Skin, Oxford University Press, New York, pp. 625–659. The author acknowledges the contribution to this Huston, J.E. 1980. Supplemental energy and protein effects on work of Professor J.H. Topps, Dr. J.R. Scaife, Dr. growth rate and mohair production in weaned Angora female kids. Progress report, Texas Agricultural Experiment Station, Md. Shahjalal, Dr. M. Souri, Dr. M. Ibraheem, Mr. J.
No. 3706. Struthers, Ms. J. Poole, Ms. M. Wallace and Mr. M.
Hynd, P.I., 1989. Effects of nutrition on wool follicle cell kinetics Birnie and Mr. Bishop. Ms. K. Hyland is also in sheep differing in efficiency of wool production. Aust. J. thanked for typing the manuscript. Agric. Res. 40, 409–417.
Ibraheem, M., Galbraith, H., Scaife, J.R., Ewen, S.W.B., 1994. Growth of secondary hair follicles of the Cashmere goat in vitro and their response to prolactin and melatonin. J. Anat.
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