Phenotypic and genetic parameters for growth characteristics of Morkaraman sheep

Abstract

The aims of the study were to determine heritabilities of growth characteristics and growth characteristics of Morkaraman sheep raised by local breeders in Erzurum province between 2006 and 2010. Growth characteristics such as live weight and daily live weight gains of Morkaraman lambs in the various periods were examined for this purpose. The effects of some environmental factors such as herd type, sex, birth type and years on these characteristics were also examined. In the study, growth characteristics of lambs obtained from mating of 5339 ewes and 253 rams were measured based on performance tests and a selection practice was performed. Elite, multiplier flock and commercial herds were established. The heritabilities of traits in question were determined. The breeding value for daily live weight gains up to the end of grazing season in the fifth year was calculated. Birth weight, birth weight heritability, weights and weight heritability at the beginning of grazing season, weight and weight heritability at the end of grazing season, daily live weight gain up and daily live weight gain heritability to the beginning of grazing season, daily weight gain up and daily live weight gain heritability to the end of grazing season were found 3.5±0.01 kg, 0.26±0.149, 21.4±0.07 kg and 0.41±0.103, 37.4±0.09 kg and 0.43±0.138, 239±1.33 g and 0.48±0.083, 201±0.78 and 0.47±0.082, respectively. At the end of the research, to improve the growth characteristics of Morkaraman sheep and to increase live weight gain to be obtained from each lamb were targeted. As a result, the live weights at the end of grazing season of lambs, Morkaraman provided an increase of approximately 5 kg. In terms of examined growth characteristics of Morkaraman sheep measured by individual performance testing, it is determined that Morkaraman sheep can be breeded by local breeders to improve its growth traits.

Keywords:

• Morkaraman sheep
• lamb
• breeding
• growth
• heritability

1. Introduction

The sheep stock in Turkey is around 21.8 million according to 2009 data (Anonymous 2009). Local breeds constitute the highest share with approximately 97% among the breeds making up the sheep population. Morkaraman breed, which comes from fat-tailed local sheep breeds, makes up an important part of this population (20%) (Özcan 1990; Soysal 2010). Morkaraman sheep, known to have spread mainly across the eastern part of Sivas province, has been raised widely in Erzurum, Ağrı, Van, Kars and Muş provinces in Eastern Anatolian region. Morkaraman is a multi-purpose sheep breed. It is known to have a lower twin reproduction rate than some other local sheep breeds. In addition, the fat-tailed structure of this breed is a negative factor reducing the carcass efficiency.

The studies and researches on local sheep race in our country have generally been conducted by state farms. The researches intended to determine the overall performance, morphological and physiological characteristics and growing conditions of sheep populations under breeders conditions will be of great importance in introducing more effective livestock development policies. In carrying out these policies efficiently and developing the country's sheep-growing sector, the outcomes of such studies make up the most important stage. In addition to examination and evaluation of traditional sheep-growing substructure in different areas, researches intended to describe and develop local sheep populations are of significant importance (Karaca et al. 1996). This project aimed at launching breeding practices inherds under breeder conditions in eastern part and providing the sheep breeders in the region with superior quality breeding sheep and rams with regard to their growth and development properties. In addition, the project intended to create registered herds owned by local breeders and finally increase the breeder income and profit.

The results obtained in this study were compared with other studies on Morkaraman sheep. Some of these studies are summarized as follows. In a study conducted with Morkaraman at in Kars province, Geliyi and İlaslan (1978) calculated the average birth weight in male and female lambs as 3.68 kg and 3.50 kg, respectively. Akçapınar and Aydın (1984) examined the live weight of lambs according to sex and birth type. The 45 day, 60 day, 75 day, 90 day, 105 day, 120 day and 150 day average weights of the lambs were 15.06 kg, 18.20 kg, 22.54 kg, 27.86 kg, 30.80 kg and 36.09 kg for male, 13.60 kg, 17.42 kg, 20.30 kg, 24.82 kg, 27.60 kg and 31.28 kg for female, respectively. The average live weight values of male lambs reported higher than the average live weight values of female lambs in all the periods mentioned. In another study on Morkaraman herds, the average birth weight of Morkaraman lambs were calculated as 4.65 kg (Dayıoğlu et al. 1990).

Birth, 3 month, 6 month and 12 month weights of Morkaraman lambs were found as 3.22 kg, 21.15 kg, 27.00 kg and 39.04 kg for male and as 3.25 kg, 20.69 kg, 25.20 kg and 34.48 kg for female, respectively (Ulusan & Aksoy 1996). In the study conducted with Morkaraman lambs by Yaprak et al. (1996), average of birth, weaning, 90 day and the end of grazing season weights were calculated as 4.26 kg, 19.92 kg, 19.76 kg and 29.61 kg, respectively. In the study comparing fattening performance of Morkaraman single-born male lambs under different conditions, average of weights at the beginning of grazing season and weights at the end of grazing season of of unlimited breastfeeding of Morkaraman lambs were calculated as 16.2 kg and 37.3 kg, respectively (Macit et al. 1998).

In their studies carried out on Morkaraman lambs reared at Agriculture Faculty State Farm of Atatürk University, average weights at birth, the beginning of grazing season and the end of grazing season and average daily live weight gain from birth to the beginning of grazing season for the lambs were reported as 4.204 kg, 14.975 kg, 32.327 kg and 0.138 kg, respectively (Dayıoğlu et al. 1999). Birth and 3 months weight averages of Morkaraman lambs were determined as 2.93 kg and 33.9 kg, respectively (Macit et al. 2001). Esenbuğa and Dayıoğlu (2002) who aimed to determine the effects of some environmental factors on growth characteristics of Morkaraman lambs reported the average of the birth weight as 4.03 kg, 75 days weaning weight as 17.61 kg, the end of grazing season weight as 35.31 kg and daily weight gain from birth until weaning as 0.145 kg. Macit et al. (2002) in their study on Morkaraman lambs reported at the beginning of grazing season weight average as 22.0 kg.

2. Materials and methods

2.1. Material

This study was carried out to increase live weight and daily weight gains for different periods, to reserve male and female lambs for breeding according to their breeding values based on performance testing under the current conditions, to improve in terms of their growth and development features and to increase the benefits to be obtained for each sheep in a breeding program of Morkaraman sheep raised by local breeders in Erzurum province between 2006 and 2010. The 5339 ewes and 253 rams of the Morkaraman sheep breed are included in the study as animal material. Morkaraman race raised by local breeders in the region, made up the animal material of the study. A total of 5592 Morkaraman sheep owned by 42 breeders in 19 villages in Erzurum province made up the animal material of the study. Of the total, 4542 was classified into commercial (herd for breeding), 735 into multipliers flock and 315 into elite. All the records to be taken up in elite, multipliers flock and comercial herds were managed by contracted technical staff according to a plan created by project implementers.

The project “The National Project for Animal İmprovement at Breeders' Conditions” was funded by Republic of Turkey Ministry of Food, Agriculture and Livestock General Directorate of Agricultural Research and Policy.

2.2. Method

2.2.1. Records and live weight controls for various periods

Plastic ear tags were attached to both ears of study material sheep at the beginning of the project and lambs soon after their births. The lambs in all herds were weighed on a 100-g sensitive scale within 24 h following the birth. Live weights for different periods were determined by digital weighing machine with 100 g sensitive. The features recorded were as follows: ear tag of the dam, date of birth, age of ewes, birth type and sex of lambs, fertility period, birth, live weights at the time of weaning or at the beginning and end of the grazing season. The live weight gains during these periods were determined. The lambs born were standardized according to their live weights at the end of grazing season (5–5.5 months), and macro environmental factors such as birth type, sex and operational factors. Then, the breeding values were determined according to the results of the performance obtained. For the heritability to be used for determining the breeding value for live weight at the end of grazing season (Esenbuğa & Dayıoğlu 2002). The heritability to be determined in the herd as of second year was used. Manual fertility method was applied in elite and multipliers herds during the mating period. In commercial herd, random and natural mating methods were applied. Search rams were used for determining the heat so that the manual mating could be carried out healthily.

2.2.2. Statistical analysis

Live weights at birth, at the beginning of grazing season and at the end of grazing season were subjected to variance analysis. Daily live weight gains at the beginning of grazing and at the end of grazing season were calculated. Duncan test was used to test the differences between levels of factors which were statistically significant. After-grazing live weights of lambs were adjusted according to factors such as sex, type of birth, birth year and weight at the beginning of grazing. Data were analyzed basically using SAS (SAS 1999) Estimates of heritabilities were based on the variance components using the method of paternal half-sibs and then the model parameters were estimated by Harvey (1990). Open nucleus breeding system was taken as basis for developing selection models (James 1979; Roden 1994).

3. Results and discussion

3.1. Live weights

3.1.1. Birth weight

The average birth weight was 3.5±0.02 kg. It was below the value determined by Dayıoğlu et al. (1990, 1999) and Esenbuğa and Dayıoğlu (2002), while it was over the value determined by Macit et al. (1998, 2001) in studies conducted with the same sheep race. The average birth weight in male lambs was determined 3.6±0.02 kg and it was 3.4±0.02 kg in ewe lambs. These values were quite close to those obtained in a study carried out on the same race male and ewe lambs by Geliyi and İlaslan (1978) in Karacaören village of Kars province. On the other hand, they were higher than those of another study (Ulusan & Aksoy 1996). There was a significant difference between (P<0.01) the average birth weights of male and ewe lambs. When the birth weights were examined over the years, the highest value was obtained from the births in 2007 (3.9±0.02 kg). An average of 0.4 kg decrease was observed in this value through 2009. The increasing twin birth rate and the negative impact of climatic and health factors were the reasons why the birth rate was the highest at the beginning of the project and it declined in the following years. There was a quite significant difference between the average birth rates over the years (P<0.01). The average birth weights in elite, multiplier flock and commercial herds were determined as 3.5±0.01 kg, 0.01±0.02 kg and 3.4±0.03 kg, respectively. These values were higher than those obtained by Ulusan and Aksoy (1996) and Macit et al. (1998) from Morkaraman lambs. When the average birth weight was examined by years, it was found to be the lowest in 2010. Particularly, the birth weight was found to be the lowest in elite. For the last 2 years, the elite herd experienced the absence of a shepherd. Moreover, it also had health problems. In addition, an increase in twin birth rate had been observed in the herd in recent years. The impact of herd types on birth weights was determined to be quite significant (P<0.01).

3.1.2. Weights at the beginning of grazing season

The overall herd average of live weights of lambs at the beginning of grazing season was determined as 21.4±0.07 kg. This value was higher than the value found by Esenbuğa and Dayıoğlu (2002) in 75-day-old lambs and Dayıoğlu et al. (1999) at the beginning of grazing season in studies carried out on the same race lambs. On the other hand, it was lower than the value found by Macit et al. (2002). The average live weights at the beginning of grazing season were 21.9±0.08 kg and 20.9±0.08 in male and ewe lambs, respectively. The difference between the average values was found to be statistically quite significant (P<0.01). In a study carried out on Morkaraman sheep, average weight in male and ewe lambs in 75 days was determined to be 22.54 kg and 20.30 kg, respectively. They were lower than the values obtained from male lambs and higher than those obtained from ewe lambs (Akçapınar & Aydın 1984). The average live weights in single- and twin-born lambs at the beginning of grazing season were found to be 21.9±0.06 kg and 20.9±0.10 kg, respectively. This difference was determined to be statistically significant (P<0.01). The average live weight between 2007 and 2010 was the lowest in 2009 (17.5±0.10 kg). An increase was observed in this value year by year and the highest value was obtained in 2007 (25.3±0.10 kg). Season determined through years was found to be significant (P<0.01). The variability of this weight over the years can be explained by the improvement of environmental factors such as maintenance in different farms every year and feeding and barn conditions. It was determined to be 24.0±0.14 kg in elite, 20.1±0.11 kg in multiplier flock and 20.0±0.06 kg in commercial herd. The impact of herd-type factors on average weight at the beginning of grazing season was found to be significant in all herds (P<0.01).

3.1.3. Weights at the end of grazing season

The average time spent in the grazing was 162.7 days over years. Regarding the weights at the end of the grazing season, the overall average was calculated as 37.4±0.09 kg. This average value was lower than the value reported by Yaprak et al. (1996) and similar to the value reported by Macit et al. (1998). The live weight gains at the end of grazing season in male, ewe, single and twin lambs in overall herds were 39.0±1.11 kg, 35.9±1.11 kg, 37.8±0.09 kg and 37.1±2.03 kg, respectively. Regarding these average values, male lambs gained more weight than ewe lambs and single lambs more than twin lambs. The differences between average values regarding sex and birth type influencing live weight at the end of grazing season were found to be significant (P<0.01). The average weights at the end of grazing season from 2007 to 2010 were determined to increase. This increase was found to be about 5 kg and 4 kg between 2007 and 2010. This increase was very important in terms of ensuring the objectives of the improvement program. It was obtained by progress in selection, herd management and enhancement in care and feeding conditions. The differences between weight averages at the end of grazing season over years were determined to be statistically significant (P<0.01). When Table 1 is examined, it can be seen that the weights at the end of grazing season obtained the highest in elite (41.0±0.19 kg) and the lowest in multiplier (34.7±0.15 kg). The effect of sex, birth type, years and herd type on the weight average at the end of grazing season was found to be significant (P<0.01).

Table 1. The least squares means and levels of significance of the weights and the daily live weight gains for different periods in Morkaraman lambs.

		BW	WBGS	WEGS	DLWGBGS	DLWGEGS
Features	N	18,669	17,848	17,216	17,848	17,216
Overall	X±Sx	3.5±0.01**	21.4±0.07**	37.4±0.09**	239±1.33**	201±0.78**
Sex
Male	N	9277	8777	8479	8777	8479
	X±Sx	3.6±0.02	21.9±0.08	39.0±1.11	245±1.54	211±0.90
Ewe	N	9392	9071	8737	9071	8737
	X±Sx	3.4±0.02**	20.9±0.08**	35.9±1.11**	233±1.53**	191±0.89**
Birth type
Single	N	15,129	14,563	14,010	15,563	14,010
	X±Sx	3.6±0.01	21.9±0.06	37.8±0.09	251±1.24	207±0.73
Twin	N	3540	3285	3206	3285	3206
	X±Sx	3.4±0.02**	20.9±0.10**	37.1±2.03**	227±2.01**	195±1.18**
Years
2007	N	4132	3801	3513	3801	3513
	X±Sx	3.9±0.02^a	25.3±0.10^a	35.0±0.14^d	260±2.02^a	182±1.18^c
2008	N	4802	4714	4608	4714	4608
	X±Sx	3.5±0.02^b	20.5±0.09^c	36.0±0.13^c	217±1.95^c	169±1.15^d
2009	N	4852	4715	4572	4715	4572
	X±Sx	3.1±0.02^c	17.5±0.10^d	38.4±0.12^b	235±1.79^b	250±1.05^a
2010	N	4883	4618	4523	4618	4523
	X±Sx	3.2±0.02^c, **	22.3±0.09^b, **	40.4±0.12^a, **	243±1.82^b, **	203±1.07^b, **
Herd type
Elite	N	1534	1427	1362	1427	1362
	X±Sx	3.5±0.01^b	24.0±0.14^a	41.0±0.19^a	244±2.76^b	212±0.65^a
Multiplier flock	N	2258	2156	2056	2156	2056
	X±Sx	3.6±0.02^a	20.1±0.11^b	34.7±0.15^c	251±2.19^a	203±1.28^b
Commercial	N	14,877	14,265	13,798	14,265	13,798
	X±Sx	3.4±0.03^c	20.0±0.06^b	36.6±0.08^b	222±1.10^c	187±1.61^c

W; birth weight; WBGS; weight at the beginning of grazing season; WEGS; weight at the end of grazing season; DLWGBGS; daily live weight gains up to the beginning of grazing season; DLWGEGS; daily live weight gains up to the end of grazing season.

* P<0.05: Significant; **P<0.01: quite significant.

^{a, b, c, d} Means in rows with different superscripts are significantly different at P<0.S05.

3.2. Daily live weight gains

3.2.1. Daily live weight gains up to the beginning of grazing season

The average daily live weight gains up to the beginning of grazing season was 239±1.33 g. The average gains were determined to be 245±1.54 g and 233±1.53 g in male and ewe lambs; 251±1.24 g and 227±2.01 g in single and twin lambs; 260±2.02 g, 217±1.95 g, 235±1.79 g and 243±1.82 g in 2007, 2008, 2009 and 2010, respectively; 244±2.76 g, 251±2.19 g and 222±1.10 g in elite, multiplier and commercial herds, respectively. The effect of sex, birth type, years and herd type on the average daily live weight gains up to the beginning of grazing season was found to be significant (P<0.01). The daily live weight gains at the beginning of grazing season in multiplier herds were higher than those in elite and commercial herds. The negative effect of diseases in elite herd in the last 2 years decreased daily live weight gains at the beginning of grazing season. The weight at the beginning of grazing season in commercial herds involving lots of breeders got the lowest value. This was due to weaknesses in animal material, care and feeding conditions and breeders tendencies to improvement. Dayıoğlu et al. (1999) found daily live weight gains at the beginning of grazing season in a study with Morkaraman sheep in Erzurum as 183 g. This value was below the value obtained in this study.

3.2.2. Daily live weight gains up to the end of grazing season

The average daily live weight gains of the lambs up to the end of grazing season was 201±0.78 g. The average gains were determined to be 211±0.90 g and 191±0.89 g in male and ewe lambs; 207±0.73 g and 195±1.18 g in single and twin lambs; 182±1.18 g, 169±1.15 g, 250±1.05 g and 203±1.07 g in 2007, 2008, 2009 and 2010, respectively; 212±0.65 g, 203±1.28 g and 187±1.61 g in elite, multiplier and commercial herds, respectively. The effect of sex, birth type, years and herd type on the average daily live weight gains up to the end of grazing season was found to be significant (P<0.01). The live weight gains at the end of the grazing season were determined to be the highest in elite herd. Within this respect, multiplier herds got higher values than commercial herds did.

4. Estimation of heritability, genetic and environmental correlations

When Table 2 is examined, it can be seen that the heritability degree regarding birth weight was low. The heritability for weight at the beginning of grazing season and weight at the end of grazing season increased with age. The largest value in the determined heritability for daily live weight gains was estimated as daily live weight gains up to the beginning of grazing season.

Table 2. Estimates of heritability, genetic and environmental correlation between the weight and the daily live weight gains traits.

	Weight			Daily live weight gains
h^2	BW	WBGS	WEGS	DLWGBGS	DLWGEGS
BW	0.26±0.149	−0.489	−0.296	−0.489	−0.161
WBGS	−0.109	0.41±0.103	0.367	0.502	0.586
WEGS	0.060	0.631	0.43±0.138	−0.785	−0.759
DLWGBGS	−0.248	0.446	0.206	0.48±0.083	0.747
DLWGEGS	−0.126	0.278	0.433	0.729	0.47±0.082

BW, birth weight; WBGS, weight at the beginning of grazing season; WEGS, weight at the end of grazing season; DLWGBGS, daily live weight gains up to the beginning of grazing season; DLWGEGS, daily live weight gains up to the end of grazing season.

5. Conclusion

In Morkaraman lambs between 2006 and 2010, the overall average birth weight were found 3.5±0.01 kg. Male lambs and single lambs were determined as the highest value for the overall herd average of birth weights, live weights of lambs at the beginning of grazing season, live weights of lambs at the end of grazing season, daily live weight gains up to the beginning of grazing season and daily live weight gains up to the end of grazing season. While lambs born in 2007 were determined as the highest value for the overall herd average of birth weights, live weights of lambs at the beginning of grazing season and daily live weight gains up to the beginning of grazing season. Lambs born in 2009 were determined as the highest value for daily live weight gains up to the end of grazing season. Lambs born in 2010 were determined as the highest value for live weights of lambs at the end of grazing season. Commercial flocs were determined as the lowest value for the overall herd average of birth weights, live weights of lambs at the beginning of grazing season, daily live weight gains up to the beginning of grazing season and daily live weight gains up to the end of grazing season. Differences between sex, birth type, years and herd type for birth weight, live weights of lambs at the beginning of grazing season, live weights of lambs at the end of grazing season, daily live weight gains up to the beginning of grazing season and daily live weight gains up to the end of grazing season were significant.

This project was a good start for the protection, development and improvement studies of the genetic potential of Morkaraman sheep owned by the local breeders. With the help of the project, breeding rams and sheep with superior performance characteristics were obtained and they were given to the breeders. The sheep breeders were trained and the foundations of a registered breeding system were established. The related breeding unions were founded and structured. An average of 5 kg live weight gain in sheep was achieved in this study covering a period of 4 years. To sum up, the objectives were largely achieved from the beginning of the project towards the end. In terms of examined growth characteristics of Morkaraman sheep measured by individual performance testing, it is determined that Morkaraman sheep can be breeded by local breeders to improve its growth traits.

Acknowledgements

The study was carried out under The Project which was called The Breeding of Morkaraman Sheep raised in local conditions.