Abstract: The purpose of this study was to determine the level of growth characteristics and to investigate the effects of environmental factors on these characteristics in purebred Arabian foals reared at Anadolu state farm. The study was carried out on the date obtained from 1681 foals at birth, 268 foals at 6 month, 422 foals at one years of age, 160 foals at 2 years of age and 37 foals at 3 years of age between the years 1987 and 2007. Although, the effect of foaling month was insignificant (p>0.05), the effects of foaling age, foaling year and sex of foals on birth weight were significant (p<0.001-p<0.05). Colts weighed 46.27±0.40 kg at birth, while fillies weighted 45.22±0.40 kg at birth. Means of body weights at birth was 45.74±0.31 kg. The average values for withers height of colts and fillies at birth, 6 month, 1, 2 and 3 years of age were 96.66±0.08, 136.29±0.34, 142.18±0.42, 149.80±0.37 and 151.79±0.78 cm, respectively. Average values heart girth were 80.06±0.08, 148.16±0.48, 156.70±0.36, 170.96±0.54 and 175.33±0.99 cm, respectively. The average values for body length foals at birth, 6th month, 1, 2 and 3 years of age were, respectively 69.03±0.23, 122.01±0.39, 132.08±0.86, 142.04±0.46, 145.08±1.00. Averages values for cannon bone circumference were10.63±0.10, 16.64±0.07, 17.73±0.04, 18.82±0.08, 19.32±0.11, respectively. At the end this study, it was concluded that growth performance of purebred Arabian horses reared at Anadolu state farm were good. Mean values of body measurement at some periods (birth, 6 month, 1, 2 and 3 year) can be used to control growth of foals in this farm and growth performance of foals was evaluated according to these values.

INTRODUCTION

Growth of foals was determined by a lot of allele gene. Growth can be classified as prenatal growth (growth in uterine) and postnatal growth (growth after birth), which can be observed well and measured quantitatively. Growth in uterine or prenatal growth was evaluated with birth weight. However, postnatal growth or growth after birth was evaluated with body measurements in successive intervals.

Growth of foals can be affected by many factors, some genetic (breed of mare, breed of stallions, etc.) others environmental. Environmental factors can be classified as factors with measurable effects (age of mares, parity, foaling year, breeding month, etc.) and factors with un-measurable effects (infectious diseases, parasitic enfestations, etc.). The measurable effects can be determined and these factors can be used in the management of the farm (Yalçin, 1975; Cilek, 2008).

Growth of foals can be evaluated and can be controlled with changes of measurements of wither height, cannon bone circumference, heart girth and body length. Therefore, factors affecting body measurements and growth of foals should be known well. Low values of measurement of body in certain time can be reason of insufficient feeding and chronic diseases and can be used management in the farm.

Demirtel (1975) reported, the average values of wither height, heart girth and cannon bone circumference in purebreds were 135.3-170.2 and 19.2 cm for females and 137.6-172.0 and 20.5 cm for males, respectively at the age of 3 at Karacabey state farm in Balikesir province in Turkey.

In Anadolu state farm, Average values for withers height of colts and filies at birth and 6th month were, respectively 96.40 and 95.38 cm, 128.89 and 128.26 cm, average values heart girth were 79.38 and 79.29 cm, 133.40 and 133.13 cm in the same order (Koç, 1990). Colt weighed 45.36 kg at birth and 197.17 kg at 6th month while filies weighted 44.60 kg at birth and 192.45 kg at 6th month. The average values for body length of colts and fillies at birth and 6th month were 68.15 and 68.07 cm, 119.55 and 117.86 cm, respectively and averages values for cannon bone circumference were 10.78 and 10.68 cm, 15.73 and 15.51 cm, respectively. Average values of the same traits were, respectively 152.24 and 18.67 cm for mares and 152.94 and 19.16 cm for stallions (Koç and Altinel, 1992).

Arabian colts weighted 46.35 kg at birth, 276.74 kg at 12th month and 372.27 kg at 24th month while filies weighted 45.65 kg at birth, 264.67 kg at 12th month, 356.67 kg at 24th month and 402.0 kg at 36 th month the effect of sex on the 6th month cannon bone circumference was significant (Altinel and Küçük, 1992).

Height at withers, circumference of front shank, chest girth, chest width, body length and height at rump of mares ageing 12-60 months were found as 151.0±0.55, 19.2±0.08, 165±0.62, 37.2±0.16, 139.2±0.81 and 142.3±0.23 cm, respectively. The differences among age groups were determined as statisticaly significant (Özdemir, 1998).

The average values of height at withers, heart girth and cannon bone circumference for 224 colts and 319 fillies younger than 24 months were calculated to be 141.634±0.212, 152.99±0.33 cm and 17.87±0.04 and 140.826±0.18, 153.94±0.33 and 17.47±0.04 cm, respectively. In addition, the average values of these body measurements were calculated for 311 colts and 73 fillies 25-36 months old as follows: 152.099±0.16, 173.61±0.25 cm and 19.58±0.03 cm and 149.288±0.32, 171.26±0.69 and 18.28±0.07 cm, respectively (Dogan et al., 2002).

In native horses in Van region of Turkey, the least squares means of height at withers, body length, height at rump, chest depth, chest width, heart girth circumference and cannon circumference were 137, 130, 136, 56, 46, 165 and 17.4 cm, respectively. The effect of age on body length and chest width was significant (p<0.05 and p<0.01) (Bayram et al., 2005).

Effects of ages of dam, sex and year of birth on the weights of foals at birth and 6 month were investigated. The effect of age of dam on birth weight was significant. The effects of ages of dam of variation on 6th month weights of foals were not significant. Effect of year of birth on birth weight and 6th month weight were not significant. The effect of sex was significant only for weight at 6th month of age (Koç and Altinel, 1992).

This study was conducted to investigate the environmental factors affecting growth traits of purebred Arabian horse raised between 1987 and 2007 at the Anadolu state farm.

MATERIALS AND METHODS

This study was carried out to determine birth weight, height at withers, heart girth and cannon bone circumference and body length measurements in purebred Arabian colts and fillies at Anadolu State Farm. Data obtained from the 1987-2007 breeding data and marketing catalogue for birth, 6 months of age, 1, 2 and 3 years of age were used. The effects of age of dam, sex and genotypes on the growth characteristics (body measurements and birth weight) were investigated. The effects of age of dam, sex of foal, foaling year and foaling month on the growth characteristics were investigated.

Fourteen age groups were formed beginning from 5 years and ending at 18 years and older for foaling age; 5 groups for foaling month (from January to May), 2 groups for sex of foals and 21 groups for calving year, between 1987 and 2007. Environmental factors which influenced birth weight, height at withers, heart girth and cannon bone circumference and body length were investigated. The General Linear Model (GLM) was used for variance analyses of milk yield traits. Duncan’s multiple range test was used for multiple comparisons.

RESULTS AND DISCUSSION

The least square means of withers height, cannon bone circumference, heart girth and body length of foals at birth was presented Table 1. Effects of sex of foals, foaling age, foaling month and foaling year on withers height at birth were statistically very significant (p<0.001). Withers height at birth was the shortest at 94.84±0.22 cm in 5 years of age, the highest at 97.64±0.37 cm in 17 years of age. Withers height at birth was the shortest at 95.84±0.18 at January, the highest at 97.27±0.13 at February.

Effect of foaling year on cannon bone circumference at birth was very significant (p<0.001). Effects of other factors were statistically insignificant (p>0.05).

Cannon bone circumference at birth changed from 9.53±0.33 at 2006 to 11.69±0.37 at 1994. Foaling age and foaling years and sex of foal on birth weight was significant (p<0.001- 0.05). Birth weight was the Although, effect of foal sex on body length at birth was insignificant, effects of foaling year, month and age on body length were significant (p<0.001-0.05). Effect of foaling year, age of mares and sex of foals on Heart girth was significant (p<0.001-0.05). From 1681 birth measurements, The least square means for withers height, cannon bone circumference, birth weight, heart girth and body length were 96.66±0.08, 10.63±0.10, 45.74±0.31, 80.05±0.08 and 69.03±0.23 cm, respectively. These data at birth correspond to those reported by Koç (1990) and Altinel and Kucuk (1992).

The least square means of withers height, cannon bone circumference and heart girth and body length at 6 month of age foals were presented in Table 2.

Table 1:	The least square means of withers height, cannon bone circumference, heart girth and body length of foals at birth

Effect of foaling month and foaling year on withers height at 6 month of age were statistically very significant (p<0.001-0.05). Withers height was the shortest at April at 135.37±0.46 cm and the highest at 136.84±0.64 at January, 125.95±1.18 at 2000 and the highest at 153.68±0.84 at 2005. Effects of foaling age and foaling year on cannon bone circumference at 6 month of age were significant (p<0.001-0.05). Effects of foaling month and foaling year on heart girth at 6 month of age were significant (p<0.001). Effects of foaling year on body length only was statistically significant (p<0.001). From 268 data, the least square means of withers height, cannon bone circumference and heart girth and body length at 6 month of age foals were 136.30±0.34, 16.64±0.06, 148.16±0.48 and 122.01±0.39. These values at 6th month were higher than those reported by Koç (1990) and Koç and Altinel (1992).

The least square means of withers height, cannon bone circumference, body length and heart girth at 1 year of age foals were presented in Table 3. Effects of foaling month and foaling year on withers height, cannon bone circumference and heart girth were significant (p<0.001). Effects of sex of foals on Cannon bone circumference was significant (p<0.001). Effect of foaling age of mares on all traits (withers height, cannon bone circumference, body length and heart girth) was insignificant (p>0.05). Effects of all factors (age of mares, foaling age, foaling month, sex of foals) on body length were insignificant (p>0.05).

Table 2:	The least square means of withers height, cannon bone circumference and heart girth and body length at 6 month of age foals

From 422 data, the least square means of withers height, cannon bone circumference and heart girth and body length at 1 years of age foals were 142.18±0.42, 17.73±0.04, 156.696±0.36 and 132.08±0.86. These values at 1 years of age were higher than those reported by Özdemir (1998).

The least square means of withers height, cannon bone circumference, heart girth and body length at 2 years of age foals were presented in Table 4. Effect of foaling year on all traits (withers height, cannon bone circumference, body length and heart girth) was significant (p<0.001-0.05). Effects sex of foal on cannon bone circumference and wither height were significant (p<0.001-0.05). Effects of foaling month and foaling age on all traits were insignificant (p>0.05). From 160 data, the least square means of withers height, cannon bone circumference and heart girth and body length at 2 years of age foals were 149.80±0.37, 18.82±0.08, 170.96±0.54 and 142.04±0.46. These values at 2 years of age were higher than reported in literature (Özdemir, 1998; Dogan et al., 2002).

Body measurement values in this study were higher than values of native horses in Turkey reported by Bayram et al. (2005).

The least square means of withers height, cannon bone circumference, heart girth and body length at 3 years of age foals was presented in Table 5. Effect of foaling month on cannon bone circumference was significant (p<0.05). From 160 data, the least square means of withers height, cannon bone circumference and heart girth and body length at 3 years of age foals were 151.79±0.78, 19.32±0.11, 175.33±0.99 and 145.1±1.00. These values at 3 years of age were nearly higher those reported in literature (Demirtel, 1975; Özdemir, 1998; Dogan et al., 2002).

Body measurements at birth correspond to literature (Koç, 1990; Altinel and Küçük, 1992) for Purebred Arabian foals. However, Body measurements at 6th month, 1st, 2nd and 3rd year was higher literature (Demirtel, 1975; Koç and Altinel, 1992; Özdemir, 1998; Dogan et al., 2002). These data demonstrate that growth of foals after birth was better in Anadolu state farm.

The average values for withers height of colts and fillies at birth, 6 month, 1, 2 and 3 years of age were 96.66±0.08, 136.29±0.34, 142.18±0.42, 149.80±0.37 and 151.79±0.78 cm, respectively.

Table 3:	The least square means of withers height, cannon bone circumference, heart girth and body length at 1 years of age foals

Average values heart girth were 80.06±0.08, 148.16±0.48, 156.70±0.36, 170.96±0.54 and 175.33±0.99 cm, respectively. The average values for body length foals at birth, 6th month, 1 years of age, 2 years of age and 3 years of age were, respectively 69.03±0.23, 122.01±0.39, 132.08±0.86, 142.04±0.46, 145.08±1.00. Averages values for cannon bone circumference were 10.63±0.10, 16.64±0.07, 17.73±0.04, 18.82±0.08, 19.32±0.11, respectively.

Effect of age of mare on body measurements at birth was significant (p<0.001), except for cannon bone circumference. Body measurements and weight at birth were lowest at 5 years of age mares. It can be said that birth weight increases to 12 years of age, then it decrease after 12 years of age. It may be caused by material (uterine) environment. Lower body measurement and birth weight for foaling mares at 5 years of age may be associated with that reproductive organs are not completely mature. Lower body measurement and birth weight in older mares (18>) may be associated with degenerative endometrial changes.

Effect of foaling month on body measurement and birth weight was insignificant except for withers height.

Except for cannon bone circumference, effect of sex of foals on body measurement and weight was significant. Differences of birth weight may be by caused attention and feeding differences among years.

All body measurements for colts were higher than measurements for fillies. Growth of colts rapidly in uterine may be caused testosterone hormone which stimulates growth of foals.

Measurements of born foals in January, February and March was higher than measurements of born foals in April and May. Born foals in April and May are 6 month of age at winter. Because of bad nutritive resources and insufficient feeding in autumn, born foals in April and May have low body measurement. Born foals in January, February and March are 6 month of age at summer. Born foals in January, February and March have high body measurement because of availability of green fodder during the spring and summer. Difference among colts and fillies was insignificant at 6 month of age. Although sex of foals on body measurements was insignificant, it was found that males generally have greater body measures than females, in agreement with (Özdemir, 1998).

Table 4:	The least square means of withers height, cannon bone circumference, heart girth and body length at 2 years of age foals

Table 5:	The least square means of withers height, cannon bone circumference, heart girth and body length at 3 years of age foals

In this study, growth traits of purebred Arabian foals under the conditions of Anadolu State farm was higher than those reported in the literature (Demirtel, 1975; Koç, 1990; Altinel and Küçük, 1992; Koç and Altinel, 1992; Özdemir, 1998; Dogan et al., 2002).

ACKNOWLEDGMENT

The author would like to express their thanks to the personnel of the Anadolu State farm, the personnel of the TIGEM, Mehmet Koç, Ahmet Mahmut Köse and Sinan Çilek which help to collect data.

CONCLUSION

The results of this study have shown that the under the conditions of Anadolu state farm purebred Arabian foals perform well in respect of growth traits is higher than those reported in the literature (Demirtel, 1975; Koç, 1990; Altinel and Küçük, 1992; Koç and Altinel, 1992; Özdemir, 1998; Dogan et al., 2002). It can be concluded that purebred Arabian foals are raised successfully for growth traits on Anadolu state farm and under steppe climate conditions in Turkey. It is concluded that better growth performance levels can be obtained by culling foals with low body measurement, by selecting foals with high body measurement and by better feeding and attention of foals. Mean values of body measurement in this study can be used to control growth of foals in this farm at some periods (birth, 6 month, 1, 2 and 3 year) and growth performance of foals was evaluated according to these values.