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Melatonin implantation from winter solstice could extend the cashmere growth phase effectively
Small Ruminant Research 99 (2011) 48–53
Contents lists available at ScienceDirect
Small Ruminant Research journal homepage: www.elsevier.com/locate/smallrumres
Melatonin implantation from winter solstice could extend the cashmere growth phase effectively夽 Yuyan Cong ∗ , Hongwei Deng, Yali Feng, Qian Chen, Yu Sun College of Animal Science & Veterinary Medicine, Shenyang Agricultural University, No. 120 Dongling Road, Shenyang 110866, PR China
a r t i c l e
i n f o
Article history: Received 21 October 2010 Received in revised form 15 March 2011 Accepted 28 March 2011 Available online 22 April 2011 Keywords: Melatonin Cashmere growth Follicle activity Liaoning cashmere goats
a b s t r a c t The effects of melatonin on cashmere growth in Liaoning cashmere goats were studied by treatment with melatonin implants from December (winter solstice) to June. Thirty-two castrated Liaoning cashmere goats were randomly allotted to 2 treatment groups, with 8 replicates of 2 goats per treatment group. In the experimental (E) group the goats were given melatonin implants subcutaneously with 2 mg per kilogram of BW, while in the control (C) group goats had no implant. All goats were fed a balanced diet under the same environmental conditions. Feed intake and live weight were recorded. Plasma melatonin concentration, cashmere growth rate, cashmere fibre diameter and secondary follicle activity were determined on samples taken monthly from December to June. There was no significant effect of melatonin implantation on feed intake and live weight. Plasma melatonin concentrations declined significantly with time in C but not in E, so that levels in E were significantly higher than in C from January to June. Cashmere growth rate decreased significantly with time in both E and C, but growth in C was less than in E from January to March, when it ceased completely in C. Cashmere fiber diameter was unaffected by time or treatment. Secondary follicle activity decreased significantly in both groups, but more rapidly in C than in E. Melatonin implants could be an effective way to increase cashmere production after the winter solstice. © 2011 Elsevier B.V. All rights reserved.
1. Introduction Cashmere is the finest and softest animal fiber, and is exclusively used in luxurious textile products. Cashmere growth exhibits seasonal rhythm, which arises from circannual changes of natural photoperiod. Cashmere begins to grow around summer solstice, with growing faster and faster from July to December and growing slower and slower from winter solstice on, and it comes to cease in
夽 The work was supported by National Key Technology R & D Program (Nos. 2008BADB2B05 and 2009BADA5B02) and part by the Science and Technology funds from Liaoning Education Department (No. 2008638). ∗ Corresponding author. Tel.: +86 24 88487156; fax: +86 24 88487156. E-mail addresses: [email protected], [email protected] (Y. Cong). 0921-4488/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.smallrumres.2011.03.055
February, and shedding occurs around April or May. It is clear that winter solstice is the turning point of cashmere growth from fast to slow. The seasonal rhythm of cashmere growth is closely modulated by the incretion, especially by the hormone secretion, which is affected by the seasonality of sunlight. Studies show that, melatonin is the critical path between photoperiod and cashmere growth (Teh et al., 1991). Melatonin implants, injection or artificial lighting control could stimulate cashmere growth in varying degrees in telogen phase (Betteridge et al., 1987; Moore et al., 1989; Litherland et al., 1990; Welch et al., 1990; Teh et al., 1991; Nixon et al., 1993; Gebbie et al., 1994; Jia, 1996; Liu et al., 1998 and Wang et al., 2006). Melatonin implantation could extend the cashmere growth phase (O’Neill et al., 1992). The cyclical growth of cashmere is in response to the cyclical activation of secondary follicles. In an annual
Y. Cong et al. / Small Ruminant Research 99 (2011) 48–53
period, the activation of secondary follicles experiences the three phases of anagen, catagen and telogen in general (Stenn et al., 1998; Stenn and Paus,2001). In April, with the old cashmere shedding, the secondary follicles begin to be activated, and they come into the anagen phase after the summer solstice, and into catagen phase and telogen phase gradually after the winter solstice (Zhang et al., 2005). So the key to prolonging cashmere growing period is to prevent the secondary follicles from coming into catagen phrase and telogen phrase. Studies suggest that the cyclical activation of the follicles is correlative with the change of melatonin concentration in vivo. When the melatonin concentration in blood increases, the secondary follicle activity also increased; if not, it would decrease. But melatonin receptors do not exist in follicles in goats, so melatonin probably plays the role of stimulating secondary follicles to promote cashmere growth in other physiological ways (Dicks et al., 1996). Recently, some studies suggest that this physiological role of melatonin may be played through prolactin. Melatonin can promote cashmere growth, which may result from that melatonin can reduce the plasma prolactin concentration (Nixon et al., 1993; Emesih et al., 1993; Wuliji et al., 2003, 2006; Santiago-Moreno et al., 2004). The mechanism of that melatonin affects the cashmere growth needs to be confirmed further. Liaoning cashmere goat is an excellent breed in China, which is known as “Chinese National Treasure”, because of its higher cashmere yield, higher net cashmere rates, longer cashmere fibers, more suitable cashmere fineness, more stable heritability and more significant effects on improving low-yield goats. It is very important in China, even all around the world. Like other cashmere goats, the cashmere growth exhibits the seasonal rhythm in Liaoning cashmere goats. However, the cashmere growth was initiated earlier, and its growth phase is longer in this breed of cashmere goats. The cashmere growth begins in June and ceases in following March, so the whole growth phase is nine months. The anagen phrase of cashmere growth is from July to November, and September is the peak month of cashmere growth in Liaoning cashmere goats (Qu and Wang, 1993). Obviously, the cashmere growth exhibits a special rhythm in Liaoning cashmere goats. Consequently, it is important for the development of cashmere goat industry all over the world to reinforce the study on Liaoning cashmere goats to activate the cashmere growing in telogen phase and to increase the cashmere yield further. However, little literature is available on the effects of melatonin implanted from winter solstice, let alone in Liaoning cashmere goats. Further studies are still necessary. We conducted this study to evaluate the effect of melatonin implantation from winter solstice on the cashmere growth in catagen phase and telogen phase in Liaoning cashmere goats. We also analyse its effect on the secondary follicle activity and the melatonin concentration in blood, so that we could make preliminary known the mechanism of melatonin in affecting the cashmere growth in Liaoning cashmere goats and realize the cashmere growing in telogen phase.
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2. Materials and methods 2.1. Animals and treatments Thirty-two healthy, one-year-old, 30-kg-weight and similarcashmere-yield castrated Liaoning cashmere goats were randomly allotted to 2 treatment groups, with 8 replicates of 2 goats per treatment group. The goats were given melatonin implants in experimental group (E), while the goats had no implant in control group (C) during the experimental period from winter solstice to June. Melatonin pellets were subcutaneously implanted at the base of an ear on 22 December 2009 (winter solstice) for the first time, with 2 mg per kilogram of BW according to the experimental result of Yue et al. (2007). The following melatonin implantation was on 22 February and 22 April respectively so that to provide continuous release of melatonin at a sufficient rate to maintain daytime plasma melatonin concentrations above basal levels after the beginning of the implantation. Two weeks before the experiment began, the goats had been grouped. All goats were fed the balanced diet under the same environmental conditions. The diet was formulated referenced to NRC (1985), comprised of hay, corn, wheat bran, cottonseed meal, etc, with concentrate-roughage ratio of 25:75 and 8.82 MJ metabolic energy per kilogram and 10.64% crude protein.
2.2. Sampling and measurement Feed intake was recorded weekly from the goats grouping on, in order to calculate the average daily feed intake before the experiment and during the experiment period. The goats were weighted respectively when goats grouped, the experiment began and the samples collected monthly during the experimental period, and average daily gain was calculated. Cashmere samples were collected on 22nd each month by clipping right next to skin in a 10 cm × 10 cm patch area, dyed with black hair dye on left mid-side at the beginning of the experiment. Cashmere length growth was evaluated with the monthly increased length of the undyed part of cashmere fiber, measured using ruler one by one. 200 cashmere fibers of each goat were measured each month. Cashmere fineness was evaluated with cashmere diameter. The undyed part of the cashmere samples were cut into 1–2 mm segments with two razor blades closed together. Put them onto the glass slide, dripped a drop of glycerol, covered with the cover glass, and then measured cashmere diameter using an Morphological analysis system. 200 cashmere fibers of each goat were measured each month. At the time of first melatonin implantation and on 22nd each following month during the experimental period, skin samples (1 cm2 ) were collected, following a subcutaneous injection of 1 ml procaine as a local anesthetic on the right mid-side of the goats, adjacent to the square patch clipping area. The samples had been fixed and stored in phosphatebuffered formalin (10%, w/v) for 24 h. Paraffin section was made and stained using the modified Sacpic method (Nixon, 1993). Histological observations were made using a light microscope. Active secondary follicles were determined by microscopic identification of the presence of a distinct bright red-stained inner root sheath and an enlarged bulb with a growing fiber. Non-active secondary follicles were judged by the absence of the above features and presence of a quiescent hair germ or a fiber with a brush end. In total, 10 trio follicle groups were counted on serial sections from the sebaceous gland level down to the papilla bulb. The secondary follicle activity was expressed as a percentage of the total secondary follicles. At the same time of skin samples collecting, blood samples (5 ml) were collected by venepuncture from the jugular vein to determine melatonin concentrations. After collection, blood samples were centrifuged at 1500 × g at 4 ◦ C for 20 min, plasma was recovered and stored at −70 ◦ C until analysis. Plasma melatonin concentration was determined by ELISA, using the Goat MT ELISA Kit bought from Shanghai Lengton Bioscience Co. Ltd.
2.3. Statistical analyses The data of this experiment are presented as treatment means and standard deviation marker (Figs. 1–3) or means with standard deviation (Tables 1 and 2). Ariance analysis was performed with the SPSS16.0 for Windows. F test was used for the significance test of month and significant
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Y. Cong et al. / Small Ruminant Research 99 (2011) 48–53
Fig. 1. Plasma melatonin concentration each month.
Fig. 2. Cashmere growth length each month.
Fig. 3. Secondary follicle activity each month.
Table 1 The feed intake and live weight of experimental goats. Group
Average daily feed intake(kg)
Average live weight
Before the experiment
During the experiment
Initial weight (kg)
Final weight (kg)
Average daily gain(g)
E C
0.87 ± 0.03 0.90 ± 0.04
0.94 ± 0.05 0.96 ± 0.04
31.65 ± 2.12 32.10 ± 2.47
37.52 ± 3.38 38.26 ± 2.85
32.45 ± 3.31 34.04 ± 2.37
Y. Cong et al. / Small Ruminant Research 99 (2011) 48–53
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Table 2 Cashmere diameter each month. Group
Month January
February
March
April
May
June
E C
15.63 ± 0.34 15.59 ± 0.47
15.58 ± 0.36 15.62 ± 0.45
15.60 ± 0.34 15.58 ± 0.37
15.59 ± 0.38 –
15.62 ± 0.43 –
15.60 ± 0.32 –
differences were determined by Duncan’s multiple range test. T test was used for treatment.
3. Results
3.4. Cashmere diameter There was no significant difference in cashmere diameter (Table 1) between any two months or groups (P > 0.05). The results indicate that melatonin implantation does not impact cashmere fineness in Liaoning cashmere goats.
3.1. Feed intake and live weight 3.5. Secondary follicle activity The measurements (Table 1) show that there was no significant difference between the average daily feed intake before the experiment and that during the experiment (P > 0.05), the same between Group E and Group C (P > 0.05). So the melatonin implantation did not affect feed intake of cashmere goats. Similarly, there was no significant difference of final weight between the two groups (P > 0.05), average daily gain was the same (P > 0.05). So the melatonin implantation did not affect live weight of cashmere goats.
3.2. Plasma melatonin concentration There was no significant difference in plasma melatonin concentrations (Fig. 1) between E and C at the beginning of melatonin implantation on 22nd December (P > 0.05), which indicates that the initial plasma melatonin concentrations were similar between two groups. Plasma melatonin concentrations exhibited a gradual decline in C with the time going (P < 0.05), and there was significant difference between any two months (P < 0.05). However, we did not find the significant difference of plasma melatonin concentrations between months in E (P > 0.05). There was significant difference between E and C from January to June (P < 0.05). These results indicate that melatonin implantation can increase plasma melatonin concentration in Liaoning cashmere goats.
There was no significant difference in secondary follicle activities (Fig. 3) between E and C just before melatonin implantation in February (P > 0.05), which indicates that the initial secondary follicle activities were similar between two groups. The secondary follicle activities decreased significantly with the time going in both groups (P < 0.05). There were significant differences between any two months from December to May in C (P < 0.05). However, in E, there was no significant difference between any two months from December to March (P > 0.05), and there were significant differences between April and May (P < 0.05). There was no significant difference between May and June in both E and C (P > 0.05). The value in C was lower than that in E in the same month from January to June (P < 0.05). It can clearly be seen that the decreasing rapidity of secondary follicle activity is slower in E than that in C. These results indicate that melatonin implantation can activate secondary follicle in Liaoning cashmere goats. 4. Discussion 4.1. Effect of melatonin implantation on feed intake and live weight Similarly to the study of Wang et al. (2006), the results of our study show that there was no significant effect of melatonin implantation on feed intake and live weight, which indicates that melatonin implantation did not affect the growth performance in cashmere goats.
3.3. Cashmere growth rate Cashmere growth rate (Fig. 2) was decreasing significantly with the time going (P < 0.05). In E, there was no significant difference between any two months from January to May (P > 0.05), and the same from April to June (P > 0.05), but there was significant difference between June and any one month from January to March (P < 0.05). In C, the growth length was shorter compared with E from January to March (P < 0.05), and the cashmere growth had ceased by March. It can clearly be seen that the decreasing of cashmere growth length was slower in E compared with C. These results indicate that melatonin implantation can activate the cashmere growth and prevent cashmere ceasing after March in Liaoning cashmere goats.
4.2. Effect of melatonin implantation on plasma melatonin concentration Similar to other goats, there are seasonal variations in melatonin secretion in cashmere goats, which is regulated by photoperiod, namely that short photoperiod can promote melatonin secretion, and long photoperiod can prevent melatonin secretion. By now there are some studies on melatonin implant that can provide continuous release of melatonin in vivo. The study of Yue et al. (2007) confirmed that the plasma melatonin concentration increased owing to melatonin implanted one month before summer solstice. From our study we found that melatonin implant was contributory
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Y. Cong et al. / Small Ruminant Research 99 (2011) 48–53
to maintain the plasma melatonin concentration in telogen phase, which indicates that melatonin implant can inhibit the decrease of plasma melatonin concentration in cashmere goats under long photoperiod, in fact, melatonin implantation can increase plasma melatonin concentration relative to the non-implanted, which was in accord with that of Wang et al. (2006).
significantly change (Litherland et al., 1990; O’Neill et al., 1992; Yue et al., 2007). Similarly, our data concluded that melatonin implantation promoted cashmere growth that lasted until June in Liaoning cashmere goats, but did not significantly affect the cashmere fineness. The differences of cashmere fineness in above-mentioned reports were related to the breed of cashmere goat probably.
4.3. Effect of melatonin implantation on cashmere growth
4.4. Effect of melatonin implantation on secondary follicle activity
Lots of previous studies confirm that there is significant correlation between the melatonin and cashmere growth. Liu et al. (1994) reported that administration of melatonin implant on May 26th could initiate cashmere growth after five weeks in Inner Mongolian Arbas cashmere goats, while cashmere growth initiation did not occur in control, that is to say, melatonin implant could initiate cashmere growth ahead of schedule; as a result, cashmere length was longer measured on August 30th, and cashmere yield increased measured on May 25th in the next year, in the goats with melatonin implant compared with melatonin non-implanted. Their subsequent experiment on melatonin implant, administrated on June 19th in Arbas cashmere goats, Liaoning cashmere goats and the cross of the two, confirmed the aforementioned result (Liu et al., 1998). Similarly, Yue et al. (2007) reported melatonin implant could initiate cashmere growth ahead of schedule and increase cashmere length and yield. These results suggest that melatonin implant, administrated after shedding in spring, can stimulate second cashmere growth at the end of summer and the beginning of autumn this year, and produce normal cashmere fiber in spring next year in cashmere goats. From the experiments of two consecutive years, Welch et al. (1990) concluded that melatonin implanted in October for goats could induce cashmere growth and extend the cashmere growth phase. In addition, Klören and Norton (1995) also found that melatonin supplementation in late winter extended cashmere growth phase. In our experiment, we found the cashmere length increased significantly and the cashmere continued to grow until June in Liaoning cashmere goats with melatonin implant, whereas the cashmere growth ceased in March. Based on the fore-mentioned results, we found that there was significant correlation between the cashmere growth and plasma melatonin concentration, and higher melatonin concentration could promote the cashmere growth in Liaoning cashmere goats. The effects of melatonin implant on cashmere fineness were not consistent in some reports. The study of Wang et al. (2006) discovered that melatonin implant in telogen phase could promote the cashmere growth in Inner Mongolia Arbas cashmere goats, but the cashmere diameter was lower than that in normal growing season (P < 0.01). However, some experimental results showed that melatonin implant increased cashmere yield, but cashmere diameter also increased (Moore et al., 1989; Jia, 1996; Wang, 1996). In addition, some other experiments found that melatonin implant resulted in cashmere length increased markedly (P < 0.05), but the diameter did not
Cashmere growth is modulated by secondary follicles activity. Melatonin is the main factor which has effect on the follicles activity, and there is significant correlation between follicle activity and plasma melatonin concentrations. Our study found that the secondary follicles activity exhibited a gradual decline in all goats from December to June, but there was a less strong reduction in melatonin implanted group than that in control, namely, melatonin implant could prevent falling of the secondary follicles activity. From this, it can be seen that the variations of the secondary follicles activity rest with the plasma melatonin concentration in cashmere goats. Our data indicated that melatonin implant could elevate plasma melatonin level and then increase secondary follicle activity, which is in accord with the findings of Ibraheem et al. (1994). 5. Conclusions All the results indicate that melatonin implantation could markedly increase blood melatonin concentration and activate secondary follicle and promote cashmere growth continuously. Melatonin implantation from winter solstice could be an effective way to extend cashmere growth phase. Acknowledgements We thank Dr Li Lin, Dr Dong Jing, Dr Shi Jiao and Dr Wu Gaofeng for the technical support in the experiments. This work was funded by National Key Technology R & D Program in the 11th Five year Plan of China (Nos. 2008BADB2B05 and 2009BADA5B02) and part by the Science and Technology funds from Liaoning Education Department (No. 2008638). References Betteridge, K., Devantier, B.P., Welch, R.A.S., Pomroy, W.E., Lapwood, K.P., 1987. Out of season cashmere growth in feral goats. In: Proceedings of the 2nd International Cashmere Conference ,. Lincoln College Press, New Zealand, pp. 137–144. Dicks, P., Morgan, C.J., Morgan, P.J., Kelly, D., Williams, L.M., 1996. The localisation and characterisation of insulin-like growth factor-I receptors and the investigation of melatonin receptors on the hair follicles of seasonal and non-seasonal fibre-producing goats. J. Endocrinol. 151, 55–63. Emesih, G.C., Newton, G.R., Teh, T.H., Zia, J.H., 1993. Effect of photoperiod and continuous administration of melatonin on plasma concentrations of prolactin in cashmere goats. Small Rumin. Res. 11, 247–256. Gebbie, F.E., Forsyth, I.A., Arendt, J., 1994. Effect of Melatonin, Bromocryptine and Altered Light/Temperature Pattern on Coat Growth in Daily Goats. Hononal Control of Fibre Growth and Shedding. European Fine Fibre Network, Occasional Publication No. 2. Macaulay Land Use Reseach Intistitute, Aberdeen, Scotland, pp. 97–105.
Y. Cong et al. / Small Ruminant Research 99 (2011) 48–53 Ibraheem, M., Galbraith, H., Scaife, J., Ewen, S., 1994. Growth of secondary hair follicles of the cashmere goat in vitro and their response to prolactin and melatonin. J. Anat. 185, 135–142. Jia, Z.H., 1996. Effect of exogenous melatonin dueion the production on cashmere goats. VI Inter. Conf. Goats 5 (2), 890–893. Klören, W.R.L., Norton, B.W., 1995. Melatonin and fleece growth in Australian cashmere goats. Small Rumin. Res. 17, 179–185. Litherland, A.J., Paterson, D.J., Parry, A.L., Dick, H.B., Staples, L.D., 1990. Melatonin for cashmere production. In: Proceedings of New Zealand Society of Animal Production, vol. 50 , pp. 339–343. Liu, J.C., Gui, R., Zhao, Q.S., 1994. Effects of melatonin on the cashmere growth and production in Inner Mongolia White cashmere goats. Chin. J. Zool. 29, 46–50 (in Chinese). Liu, J.C., Yin, X.Z., Fang, T.Q., 1998. Effects of melatonin on the cashmere growth and production of Chinese white goats. Chin. J. Zool. 33, 8–13 (in Chinese). Moore, R.W., Bigham, M.L., Staples, L.D., 1989. Effect of Regulin implants on spring fertility, lactation and down of cashmere does. In: Proceeding of New Zealand and Society of Animal Production, vol. 49 , pp. 39– 41. Nixon, A.J., 1993. A method for determining the activity state of hair follicles. Biotech. Histochem. 68, 316–325. Nixon, A.J., Choy, V.J., Parry, A.L., Pearson, A.J., 1993. Fiber growth initiation in hair follicles of goats treated with melatonin. J. Exp. Zool. 267, 47–56. NRC, 1985. Nutrient Requirements of Goats. Natl. Acad. Press, Washington, DC. O’Neill, K., Litherland, A.J., Hamilton, G., 1992. Melatonin for cashmere production in breeding does. Proc. N. Z. Soc. Anim. Prod. 52, 161– 164. Qu, Y.N., Wang, W., 1993. Study on the growth rhythm of Liaoning cashmere goats. Liaoning J. Anim. Husbandry Vet. Med. 2, 18–19 (in Chinese). Santiago-Moreno, J., López-Sebastián, A., del Campo, A., González-Bulnes, A., Picazo, R., Gómez-Brunet, A., 2004. Effect of constant-release melatonin implants and prolonged exposure to a long day photoperiod on
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prolactin secretion and hair growth in mouflon (Ovis gmelini musimon). Dom. Anim. Endocrinol. 26, 303–314. Stenn, K., Parimoo, S., Prouty, S.M., 1998. Growth of the hair follicle: a cycling and regenerating biological system. In: Chuong, C.-M. (Ed.), Molecular Basis of Epithelial Appendage Morphogenesis. R.G. Landes Co, Austin, TX, USA, pp. 111–130. Stenn, K.S., Paus, R., 2001. Control of hair follicle cycling. Physiol. Rev. 81, 449–494. Teh, T.H., Jia, Z.H., Ogden, K.D., Newton, G.R., 1991. The effects of photoperiod and melatonin implant on cashmere production. J. Anim. Sci. 69 (Suppl. 1), 496, Abstract. Wang, L.F., Lu, D.X., Sun, H.Z., Zhao, X.Y., Shan, D., 2006. Effects of photoperiod and melatonin on nitrogen partitioning and cashmere growth in Inner Mongolia white cashmere goats. Sci. Agric. Sin. 39, 1004–1010 (in Chinese). Wang, R. J., 1996. The regulation of nutrition and exogenous melatonin on the growth pattern of wool fiber in white cashmere goats. Master’s Thesis. Chinese Academy of Agricultural Sciences, Beijing (in Chinese). Welch, R.A.S., Gurnsey, M.P., Betteridge, K., Mitchell, R.J., 1990. Goat fibre response to melatonin given in spring in two consecutive years. Proc. N. Z. Soc. Anim. Prod. 50, 335–338. Wuliji, T., Litherland, A., Goetsch, A.L., Sahlu, T., Puchala, R., Dawson, L.J., Gipson, T., 2003. Evaluation of melatonin and bromocryptine administration in Spanish goats. II. Effect on seasonal cashmere growth, yield and fiber characteristics of does. Small Rumin. Res. 49, 41–49. Wuliji, T., Litherland, A., Goetsch, A.L., Sahlu, T., Puchala, R., Dawson, L.J., Gipson, T., 2006. Evaluation of melatonin and bromocryptine administration in Spanish goats. III. Effects on hair follicle activity, density and relationships between follicle characteristics. Small Rumin. Res. 66, 11–21. Yue, C.W., Zhang, W., Kong, X.H., Liu, H.Y., Jia, Z.H., 2007. Effect of melatonin on cashmere performance in Inner Mongolia white cashmere goats. Chin. J. Anim. Sci. 43, 32–34. Zhang, C.L., Li, J.Q., Yin, J., Zhang, Y.B., Miao, X., 2005. Study on hair follicles periodical variety in inner mongolia Arbas white cashmere goats. Chin. J. Anim. Sci. 41, 10–14 (in Chinese).
Contents lists available at ScienceDirect
Small Ruminant Research journal homepage: www.elsevier.com/locate/smallrumres
Melatonin implantation from winter solstice could extend the cashmere growth phase effectively夽 Yuyan Cong ∗ , Hongwei Deng, Yali Feng, Qian Chen, Yu Sun College of Animal Science & Veterinary Medicine, Shenyang Agricultural University, No. 120 Dongling Road, Shenyang 110866, PR China
a r t i c l e
i n f o
Article history: Received 21 October 2010 Received in revised form 15 March 2011 Accepted 28 March 2011 Available online 22 April 2011 Keywords: Melatonin Cashmere growth Follicle activity Liaoning cashmere goats
a b s t r a c t The effects of melatonin on cashmere growth in Liaoning cashmere goats were studied by treatment with melatonin implants from December (winter solstice) to June. Thirty-two castrated Liaoning cashmere goats were randomly allotted to 2 treatment groups, with 8 replicates of 2 goats per treatment group. In the experimental (E) group the goats were given melatonin implants subcutaneously with 2 mg per kilogram of BW, while in the control (C) group goats had no implant. All goats were fed a balanced diet under the same environmental conditions. Feed intake and live weight were recorded. Plasma melatonin concentration, cashmere growth rate, cashmere fibre diameter and secondary follicle activity were determined on samples taken monthly from December to June. There was no significant effect of melatonin implantation on feed intake and live weight. Plasma melatonin concentrations declined significantly with time in C but not in E, so that levels in E were significantly higher than in C from January to June. Cashmere growth rate decreased significantly with time in both E and C, but growth in C was less than in E from January to March, when it ceased completely in C. Cashmere fiber diameter was unaffected by time or treatment. Secondary follicle activity decreased significantly in both groups, but more rapidly in C than in E. Melatonin implants could be an effective way to increase cashmere production after the winter solstice. © 2011 Elsevier B.V. All rights reserved.
1. Introduction Cashmere is the finest and softest animal fiber, and is exclusively used in luxurious textile products. Cashmere growth exhibits seasonal rhythm, which arises from circannual changes of natural photoperiod. Cashmere begins to grow around summer solstice, with growing faster and faster from July to December and growing slower and slower from winter solstice on, and it comes to cease in
夽 The work was supported by National Key Technology R & D Program (Nos. 2008BADB2B05 and 2009BADA5B02) and part by the Science and Technology funds from Liaoning Education Department (No. 2008638). ∗ Corresponding author. Tel.: +86 24 88487156; fax: +86 24 88487156. E-mail addresses: [email protected], [email protected] (Y. Cong). 0921-4488/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.smallrumres.2011.03.055
February, and shedding occurs around April or May. It is clear that winter solstice is the turning point of cashmere growth from fast to slow. The seasonal rhythm of cashmere growth is closely modulated by the incretion, especially by the hormone secretion, which is affected by the seasonality of sunlight. Studies show that, melatonin is the critical path between photoperiod and cashmere growth (Teh et al., 1991). Melatonin implants, injection or artificial lighting control could stimulate cashmere growth in varying degrees in telogen phase (Betteridge et al., 1987; Moore et al., 1989; Litherland et al., 1990; Welch et al., 1990; Teh et al., 1991; Nixon et al., 1993; Gebbie et al., 1994; Jia, 1996; Liu et al., 1998 and Wang et al., 2006). Melatonin implantation could extend the cashmere growth phase (O’Neill et al., 1992). The cyclical growth of cashmere is in response to the cyclical activation of secondary follicles. In an annual
Y. Cong et al. / Small Ruminant Research 99 (2011) 48–53
period, the activation of secondary follicles experiences the three phases of anagen, catagen and telogen in general (Stenn et al., 1998; Stenn and Paus,2001). In April, with the old cashmere shedding, the secondary follicles begin to be activated, and they come into the anagen phase after the summer solstice, and into catagen phase and telogen phase gradually after the winter solstice (Zhang et al., 2005). So the key to prolonging cashmere growing period is to prevent the secondary follicles from coming into catagen phrase and telogen phrase. Studies suggest that the cyclical activation of the follicles is correlative with the change of melatonin concentration in vivo. When the melatonin concentration in blood increases, the secondary follicle activity also increased; if not, it would decrease. But melatonin receptors do not exist in follicles in goats, so melatonin probably plays the role of stimulating secondary follicles to promote cashmere growth in other physiological ways (Dicks et al., 1996). Recently, some studies suggest that this physiological role of melatonin may be played through prolactin. Melatonin can promote cashmere growth, which may result from that melatonin can reduce the plasma prolactin concentration (Nixon et al., 1993; Emesih et al., 1993; Wuliji et al., 2003, 2006; Santiago-Moreno et al., 2004). The mechanism of that melatonin affects the cashmere growth needs to be confirmed further. Liaoning cashmere goat is an excellent breed in China, which is known as “Chinese National Treasure”, because of its higher cashmere yield, higher net cashmere rates, longer cashmere fibers, more suitable cashmere fineness, more stable heritability and more significant effects on improving low-yield goats. It is very important in China, even all around the world. Like other cashmere goats, the cashmere growth exhibits the seasonal rhythm in Liaoning cashmere goats. However, the cashmere growth was initiated earlier, and its growth phase is longer in this breed of cashmere goats. The cashmere growth begins in June and ceases in following March, so the whole growth phase is nine months. The anagen phrase of cashmere growth is from July to November, and September is the peak month of cashmere growth in Liaoning cashmere goats (Qu and Wang, 1993). Obviously, the cashmere growth exhibits a special rhythm in Liaoning cashmere goats. Consequently, it is important for the development of cashmere goat industry all over the world to reinforce the study on Liaoning cashmere goats to activate the cashmere growing in telogen phase and to increase the cashmere yield further. However, little literature is available on the effects of melatonin implanted from winter solstice, let alone in Liaoning cashmere goats. Further studies are still necessary. We conducted this study to evaluate the effect of melatonin implantation from winter solstice on the cashmere growth in catagen phase and telogen phase in Liaoning cashmere goats. We also analyse its effect on the secondary follicle activity and the melatonin concentration in blood, so that we could make preliminary known the mechanism of melatonin in affecting the cashmere growth in Liaoning cashmere goats and realize the cashmere growing in telogen phase.
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2. Materials and methods 2.1. Animals and treatments Thirty-two healthy, one-year-old, 30-kg-weight and similarcashmere-yield castrated Liaoning cashmere goats were randomly allotted to 2 treatment groups, with 8 replicates of 2 goats per treatment group. The goats were given melatonin implants in experimental group (E), while the goats had no implant in control group (C) during the experimental period from winter solstice to June. Melatonin pellets were subcutaneously implanted at the base of an ear on 22 December 2009 (winter solstice) for the first time, with 2 mg per kilogram of BW according to the experimental result of Yue et al. (2007). The following melatonin implantation was on 22 February and 22 April respectively so that to provide continuous release of melatonin at a sufficient rate to maintain daytime plasma melatonin concentrations above basal levels after the beginning of the implantation. Two weeks before the experiment began, the goats had been grouped. All goats were fed the balanced diet under the same environmental conditions. The diet was formulated referenced to NRC (1985), comprised of hay, corn, wheat bran, cottonseed meal, etc, with concentrate-roughage ratio of 25:75 and 8.82 MJ metabolic energy per kilogram and 10.64% crude protein.
2.2. Sampling and measurement Feed intake was recorded weekly from the goats grouping on, in order to calculate the average daily feed intake before the experiment and during the experiment period. The goats were weighted respectively when goats grouped, the experiment began and the samples collected monthly during the experimental period, and average daily gain was calculated. Cashmere samples were collected on 22nd each month by clipping right next to skin in a 10 cm × 10 cm patch area, dyed with black hair dye on left mid-side at the beginning of the experiment. Cashmere length growth was evaluated with the monthly increased length of the undyed part of cashmere fiber, measured using ruler one by one. 200 cashmere fibers of each goat were measured each month. Cashmere fineness was evaluated with cashmere diameter. The undyed part of the cashmere samples were cut into 1–2 mm segments with two razor blades closed together. Put them onto the glass slide, dripped a drop of glycerol, covered with the cover glass, and then measured cashmere diameter using an Morphological analysis system. 200 cashmere fibers of each goat were measured each month. At the time of first melatonin implantation and on 22nd each following month during the experimental period, skin samples (1 cm2 ) were collected, following a subcutaneous injection of 1 ml procaine as a local anesthetic on the right mid-side of the goats, adjacent to the square patch clipping area. The samples had been fixed and stored in phosphatebuffered formalin (10%, w/v) for 24 h. Paraffin section was made and stained using the modified Sacpic method (Nixon, 1993). Histological observations were made using a light microscope. Active secondary follicles were determined by microscopic identification of the presence of a distinct bright red-stained inner root sheath and an enlarged bulb with a growing fiber. Non-active secondary follicles were judged by the absence of the above features and presence of a quiescent hair germ or a fiber with a brush end. In total, 10 trio follicle groups were counted on serial sections from the sebaceous gland level down to the papilla bulb. The secondary follicle activity was expressed as a percentage of the total secondary follicles. At the same time of skin samples collecting, blood samples (5 ml) were collected by venepuncture from the jugular vein to determine melatonin concentrations. After collection, blood samples were centrifuged at 1500 × g at 4 ◦ C for 20 min, plasma was recovered and stored at −70 ◦ C until analysis. Plasma melatonin concentration was determined by ELISA, using the Goat MT ELISA Kit bought from Shanghai Lengton Bioscience Co. Ltd.
2.3. Statistical analyses The data of this experiment are presented as treatment means and standard deviation marker (Figs. 1–3) or means with standard deviation (Tables 1 and 2). Ariance analysis was performed with the SPSS16.0 for Windows. F test was used for the significance test of month and significant
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Y. Cong et al. / Small Ruminant Research 99 (2011) 48–53
Fig. 1. Plasma melatonin concentration each month.
Fig. 2. Cashmere growth length each month.
Fig. 3. Secondary follicle activity each month.
Table 1 The feed intake and live weight of experimental goats. Group
Average daily feed intake(kg)
Average live weight
Before the experiment
During the experiment
Initial weight (kg)
Final weight (kg)
Average daily gain(g)
E C
0.87 ± 0.03 0.90 ± 0.04
0.94 ± 0.05 0.96 ± 0.04
31.65 ± 2.12 32.10 ± 2.47
37.52 ± 3.38 38.26 ± 2.85
32.45 ± 3.31 34.04 ± 2.37
Y. Cong et al. / Small Ruminant Research 99 (2011) 48–53
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Table 2 Cashmere diameter each month. Group
Month January
February
March
April
May
June
E C
15.63 ± 0.34 15.59 ± 0.47
15.58 ± 0.36 15.62 ± 0.45
15.60 ± 0.34 15.58 ± 0.37
15.59 ± 0.38 –
15.62 ± 0.43 –
15.60 ± 0.32 –
differences were determined by Duncan’s multiple range test. T test was used for treatment.
3. Results
3.4. Cashmere diameter There was no significant difference in cashmere diameter (Table 1) between any two months or groups (P > 0.05). The results indicate that melatonin implantation does not impact cashmere fineness in Liaoning cashmere goats.
3.1. Feed intake and live weight 3.5. Secondary follicle activity The measurements (Table 1) show that there was no significant difference between the average daily feed intake before the experiment and that during the experiment (P > 0.05), the same between Group E and Group C (P > 0.05). So the melatonin implantation did not affect feed intake of cashmere goats. Similarly, there was no significant difference of final weight between the two groups (P > 0.05), average daily gain was the same (P > 0.05). So the melatonin implantation did not affect live weight of cashmere goats.
3.2. Plasma melatonin concentration There was no significant difference in plasma melatonin concentrations (Fig. 1) between E and C at the beginning of melatonin implantation on 22nd December (P > 0.05), which indicates that the initial plasma melatonin concentrations were similar between two groups. Plasma melatonin concentrations exhibited a gradual decline in C with the time going (P < 0.05), and there was significant difference between any two months (P < 0.05). However, we did not find the significant difference of plasma melatonin concentrations between months in E (P > 0.05). There was significant difference between E and C from January to June (P < 0.05). These results indicate that melatonin implantation can increase plasma melatonin concentration in Liaoning cashmere goats.
There was no significant difference in secondary follicle activities (Fig. 3) between E and C just before melatonin implantation in February (P > 0.05), which indicates that the initial secondary follicle activities were similar between two groups. The secondary follicle activities decreased significantly with the time going in both groups (P < 0.05). There were significant differences between any two months from December to May in C (P < 0.05). However, in E, there was no significant difference between any two months from December to March (P > 0.05), and there were significant differences between April and May (P < 0.05). There was no significant difference between May and June in both E and C (P > 0.05). The value in C was lower than that in E in the same month from January to June (P < 0.05). It can clearly be seen that the decreasing rapidity of secondary follicle activity is slower in E than that in C. These results indicate that melatonin implantation can activate secondary follicle in Liaoning cashmere goats. 4. Discussion 4.1. Effect of melatonin implantation on feed intake and live weight Similarly to the study of Wang et al. (2006), the results of our study show that there was no significant effect of melatonin implantation on feed intake and live weight, which indicates that melatonin implantation did not affect the growth performance in cashmere goats.
3.3. Cashmere growth rate Cashmere growth rate (Fig. 2) was decreasing significantly with the time going (P < 0.05). In E, there was no significant difference between any two months from January to May (P > 0.05), and the same from April to June (P > 0.05), but there was significant difference between June and any one month from January to March (P < 0.05). In C, the growth length was shorter compared with E from January to March (P < 0.05), and the cashmere growth had ceased by March. It can clearly be seen that the decreasing of cashmere growth length was slower in E compared with C. These results indicate that melatonin implantation can activate the cashmere growth and prevent cashmere ceasing after March in Liaoning cashmere goats.
4.2. Effect of melatonin implantation on plasma melatonin concentration Similar to other goats, there are seasonal variations in melatonin secretion in cashmere goats, which is regulated by photoperiod, namely that short photoperiod can promote melatonin secretion, and long photoperiod can prevent melatonin secretion. By now there are some studies on melatonin implant that can provide continuous release of melatonin in vivo. The study of Yue et al. (2007) confirmed that the plasma melatonin concentration increased owing to melatonin implanted one month before summer solstice. From our study we found that melatonin implant was contributory
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to maintain the plasma melatonin concentration in telogen phase, which indicates that melatonin implant can inhibit the decrease of plasma melatonin concentration in cashmere goats under long photoperiod, in fact, melatonin implantation can increase plasma melatonin concentration relative to the non-implanted, which was in accord with that of Wang et al. (2006).
significantly change (Litherland et al., 1990; O’Neill et al., 1992; Yue et al., 2007). Similarly, our data concluded that melatonin implantation promoted cashmere growth that lasted until June in Liaoning cashmere goats, but did not significantly affect the cashmere fineness. The differences of cashmere fineness in above-mentioned reports were related to the breed of cashmere goat probably.
4.3. Effect of melatonin implantation on cashmere growth
4.4. Effect of melatonin implantation on secondary follicle activity
Lots of previous studies confirm that there is significant correlation between the melatonin and cashmere growth. Liu et al. (1994) reported that administration of melatonin implant on May 26th could initiate cashmere growth after five weeks in Inner Mongolian Arbas cashmere goats, while cashmere growth initiation did not occur in control, that is to say, melatonin implant could initiate cashmere growth ahead of schedule; as a result, cashmere length was longer measured on August 30th, and cashmere yield increased measured on May 25th in the next year, in the goats with melatonin implant compared with melatonin non-implanted. Their subsequent experiment on melatonin implant, administrated on June 19th in Arbas cashmere goats, Liaoning cashmere goats and the cross of the two, confirmed the aforementioned result (Liu et al., 1998). Similarly, Yue et al. (2007) reported melatonin implant could initiate cashmere growth ahead of schedule and increase cashmere length and yield. These results suggest that melatonin implant, administrated after shedding in spring, can stimulate second cashmere growth at the end of summer and the beginning of autumn this year, and produce normal cashmere fiber in spring next year in cashmere goats. From the experiments of two consecutive years, Welch et al. (1990) concluded that melatonin implanted in October for goats could induce cashmere growth and extend the cashmere growth phase. In addition, Klören and Norton (1995) also found that melatonin supplementation in late winter extended cashmere growth phase. In our experiment, we found the cashmere length increased significantly and the cashmere continued to grow until June in Liaoning cashmere goats with melatonin implant, whereas the cashmere growth ceased in March. Based on the fore-mentioned results, we found that there was significant correlation between the cashmere growth and plasma melatonin concentration, and higher melatonin concentration could promote the cashmere growth in Liaoning cashmere goats. The effects of melatonin implant on cashmere fineness were not consistent in some reports. The study of Wang et al. (2006) discovered that melatonin implant in telogen phase could promote the cashmere growth in Inner Mongolia Arbas cashmere goats, but the cashmere diameter was lower than that in normal growing season (P < 0.01). However, some experimental results showed that melatonin implant increased cashmere yield, but cashmere diameter also increased (Moore et al., 1989; Jia, 1996; Wang, 1996). In addition, some other experiments found that melatonin implant resulted in cashmere length increased markedly (P < 0.05), but the diameter did not
Cashmere growth is modulated by secondary follicles activity. Melatonin is the main factor which has effect on the follicles activity, and there is significant correlation between follicle activity and plasma melatonin concentrations. Our study found that the secondary follicles activity exhibited a gradual decline in all goats from December to June, but there was a less strong reduction in melatonin implanted group than that in control, namely, melatonin implant could prevent falling of the secondary follicles activity. From this, it can be seen that the variations of the secondary follicles activity rest with the plasma melatonin concentration in cashmere goats. Our data indicated that melatonin implant could elevate plasma melatonin level and then increase secondary follicle activity, which is in accord with the findings of Ibraheem et al. (1994). 5. Conclusions All the results indicate that melatonin implantation could markedly increase blood melatonin concentration and activate secondary follicle and promote cashmere growth continuously. Melatonin implantation from winter solstice could be an effective way to extend cashmere growth phase. Acknowledgements We thank Dr Li Lin, Dr Dong Jing, Dr Shi Jiao and Dr Wu Gaofeng for the technical support in the experiments. This work was funded by National Key Technology R & D Program in the 11th Five year Plan of China (Nos. 2008BADB2B05 and 2009BADA5B02) and part by the Science and Technology funds from Liaoning Education Department (No. 2008638). References Betteridge, K., Devantier, B.P., Welch, R.A.S., Pomroy, W.E., Lapwood, K.P., 1987. Out of season cashmere growth in feral goats. In: Proceedings of the 2nd International Cashmere Conference ,. Lincoln College Press, New Zealand, pp. 137–144. Dicks, P., Morgan, C.J., Morgan, P.J., Kelly, D., Williams, L.M., 1996. The localisation and characterisation of insulin-like growth factor-I receptors and the investigation of melatonin receptors on the hair follicles of seasonal and non-seasonal fibre-producing goats. J. Endocrinol. 151, 55–63. Emesih, G.C., Newton, G.R., Teh, T.H., Zia, J.H., 1993. Effect of photoperiod and continuous administration of melatonin on plasma concentrations of prolactin in cashmere goats. Small Rumin. Res. 11, 247–256. Gebbie, F.E., Forsyth, I.A., Arendt, J., 1994. Effect of Melatonin, Bromocryptine and Altered Light/Temperature Pattern on Coat Growth in Daily Goats. Hononal Control of Fibre Growth and Shedding. European Fine Fibre Network, Occasional Publication No. 2. Macaulay Land Use Reseach Intistitute, Aberdeen, Scotland, pp. 97–105.
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