Comparative characteristics of the inheritance of breeding traits in different mating schemes of grey Karakul sheep populations

Características comparativas da herança de características reprodutivas em diferentes esquemas de acasalamento de populações de ovelhas Karakul cinzentas

Abstract

The study was conducted at the base farms of “OtrarAgro” LLP and “Narmet” farm in the Turkestan region, both specializing in the breeding of Karakul sheep of grey coloration. According to the research findings, a comparative assessment of the inheritance patterns of breeding traits in the offspring obtained from grey Karakul rams with silvery and bluish fur shades, bred in different ecological and climatic zones (local and imported), when mated to black ewes, demonstrated that the highest inheritance rate of the jacket-type fur with silvery shade was observed in the progeny of imported rams (63.0%), compared to 55.8% in local rams, with a difference of 7.2% (P>0.999). A similar trend was recorded for the bluish-colored jacket-type fur: 59.0% in the progeny of imported rams versus 50.7% in local ones, with a difference of 8.3% (P>0.999). The share of elite- and class I-grade lambs among offspring of local and imported silvery-grey rams reached 80.1% and 85.6%, respectively, with a difference of 5.5% (P>0.99) in favor of imported rams. Comparable dynamics were observed in the progeny of bluish-grey rams: 80.5% and 88.5%, respectively, with an average difference of 8.0% (P>0.999). In heterogeneous matings of local silvery-grey rams to black ewes, the inheritance ratio in the offspring was 51.6% black and 48.4% grey. When imported silvery-grey rams were used, the ratio was 51.0% and 49.0%, maintaining a consistent 1:1 distribution. In heterogeneous matings involving bluish-grey rams and black ewes, the inheritance ratio similarly amounted to 51.6% black and 48.4% grey. These results reconfirm the regularity of the 50:50 distribution of grey versus black lambs. Evaluation of parameters determining the qualitative traits of silvery-patterned fur in both mating groups revealed the following: the correlation between white fiber content and evenness/expression of coloration was highly significant (r=0.104±0.007, P<0.001), with the magnitude of influence ranging from 8.1-12.6% and 25.7-28.8%, respectively. The correlation between the excessive white fiber length and its effect on evenness/expression was also statistically significant (r=0.109±0.008, P<0.001 and r=0.336±0.004, P<0.001). In the third and fourth mating variants, the corresponding parameters were: content of white fibers versus evenness/expression – r=0.111±0.006, P<0.001; excessive length of white fibers and its effect on evenness/expression – r=0.113±0.006, P<0.001 and r=0.342±0.005, P<0.001; with the magnitude of influence ranging from 9.4-13.7% and 33.1-37.1%, respectively. A highly significant genetic association (P<0.001) was identified between white fiber content and excessive fiber length. The breeding and genetic relevance of these findings confirms that the direction of the presented research aligns with modern requirements of applied science and contributes to improving the efficiency of fur sheep breeding.

Keywords:
rams; ewes; fur types; black and grey coloration; silvery and bluish shades

Resumo

O estudo foi conduzido nas fazendas base da “OtrarAgro” LLP e da fazenda “Narmet”, na região do Turquestão, ambas especializadas na criação de ovelhas Karakul de coloração cinza. De acordo com os resultados da pesquisa, uma avaliação comparativa dos padrões de herança de características genéticas na progênie obtida de carneiros Karakul cinza com tons de pelagem prateados e azulados, criados em diferentes zonas ecológicas e climáticas (locais e importados), quando acasalados com ovelhas pretas, demonstrou que a maior taxa de herança da pelagem tipo jaqueta com tom prateado foi observada na progênie de carneiros importados (63,0%), em comparação com 55,8% em carneiros locais, com uma diferença de 7,2% (P>0,999). Uma tendência semelhante foi registrada para a pelagem tipo jaqueta de cor azulada: 59,0% na progênie de carneiros importados versus 50,7% em carneiros locais, com uma diferença de 8,3% (P>0,999). A proporção de cordeiros de elite e classe I entre os descendentes de carneiros cinza-prateados locais e importados atingiu 80,1% e 85,6%, respectivamente, com uma diferença de 5,5% (P>0,99) em favor dos carneiros importados. Dinâmicas comparáveis ​​foram observadas na progênie de carneiros cinza-azulados: 80,5% e 88,5%, respectivamente, com uma diferença média de 8,0% (P>0,999). Em acasalamentos heterogêneos de carneiros cinza-prateados locais com ovelhas pretas, a proporção de herança na progênie foi de 51,6% pretos e 48,4% cinzas. Quando carneiros cinza-prateados importados foram utilizados, a proporção foi de 51,0% e 49,0%, mantendo uma distribuição consistente de 1:1. Em cruzamentos heterogêneos envolvendo carneiros cinza-azulados e ovelhas pretas, a proporção de herança foi similar, de 51,6% para preto e 48,4% para cinza. Esses resultados reconfirmam a regularidade da distribuição de 50:50 entre cordeiros cinza e preto. A avaliação dos parâmetros que determinam as características qualitativas da pelagem com padrão prateado em ambos os grupos de cruzamento revelou o seguinte: a correlação entre o teor de fibra branca e a uniformidade/expressão da coloração foi altamente significativa (r=0,104±0,007, P<0,001), com a magnitude da influência variando de 8,1 a 12,6% e de 25,7 a 28,8%, respectivamente. A correlação entre o comprimento excessivo da fibra branca e seu efeito na uniformidade/expressão também foi estatisticamente significativa (r=0,109±0,008, P<0,001 e r=0,336±0,004, P<0,001). Nas terceira e quarta variantes de acasalamento, os parâmetros correspondentes foram: teor de fibras brancas versus uniformidade/expressão – r=0,111±0,006, P<0,001; comprimento excessivo de fibras brancas e seu efeito na uniformidade/expressão – r=0,113±0,006, P<0,001 e r=0,342±0,005, P<0,001, com a magnitude da influência variando de 9,4 a 13,7% e de 33,1 a 37,1%, respectivamente. Uma associação genética altamente significativa (P<0,001) foi identificada entre o teor de fibras brancas e o comprimento excessivo das fibras. A relevância genética e de melhoramento destes achados confirma que a direção da pesquisa apresentada está alinhada com as exigências modernas da ciência aplicada e contribui para melhorar a eficiência da criação de ovinos de pele.

Palavras-chave:
carneiros; ovelhas; tipos de pelagem; coloração preta e cinza; tons prateados e azulados

1. Introduction

Nowadays, sheep breeding stands as one of the most vital sectors within global animal husbandry (Kulzhanova et al., 2024a). Kazakh breeds of sheep are characterized by good quality indicators (Kulzhanova et al., 2024b).

The preservation and rational utilization of existing genetic resources of Karakul sheep with black and grey fur coloration hold significant breeding importance. The objective of this study was to perform a comparative assessment of the inheritance patterns of key selection traits in the offspring – specifically fur type, coloration, ratio and length of white to black fibers, and quality class – when using grey Karakul rams with silvery and bluish fur shades, originating from different ecological and climatic environments (local and imported), mated to black ewes.

A review of the global scientific literature in this field revealed insufficient information regarding the inheritance of white and black fibers – their ratios and length variation – and their effect on uniformity and intensity of coloration under different mating schemes in grey Karakul sheep breeding. This knowledge gap served as a primary rationale in selecting the direction of the research.

Under current market-economy conditions, the development of Karakul sheep with rare colorations, shades, and valuable fur types has gained particular relevance among commercial producers. Grey coloration in Karakul sheep belongs to the category of complex pigmentation and results from the mixture of white and black fibers that vary in number, length, and degree of pigmentation.

Inheritance of the grey coloration, depending on parental combinations by color and shade across different populations, demonstrates a genetic predisposition toward specific phenotypes. When mating jacket-type × jacket-type parents, 53.9% of the offspring inherited the parental jacket-type fur, whereas heterogeneous matings (♂ jacket-type × ♀ ribbed or Caucasian type) resulted in 45.1% and 46.8% jacket-type lambs, respectively (Mustiyar et al., 2019; Amerkhanov et al., 2018).

In the first mating scheme (♂ grey with uniform silvery coloration × ♀ black jacket-type with intensive pigmentation), the proportion of grey-coated offspring was 50.6%. In the second scheme (♂ black jacket-type with intensive pigmentation × ♀ grey with uniform silvery coloration), this parameter was 49.6%. The proportion of black-coated lambs in these combinations was 49.4% and 50.4%, respectively (Parzhanov et al., 2024).

In homogeneous matings of grey Karakul sheep, inheritance of grey coat color in the first generation reached 74.5%, producing a 3:1 ratio of grey to black phenotypes. In heterogeneous matings, where grey rams were mated to black ewes (♂ grey × ♀ black), the inheritance rate of grey coloration was 50.7%. In reciprocal matings (♂ black × ♀ grey), the proportion of grey offspring was 48.6%. Under these mating combinations, the ratio of grey to black coat colors remained balanced at approximately 1:1.

An analysis of grey coat inheritance depending on parental coat color and shade combinations across different populations indicates that these parameters reflect genetic predisposition toward specific phenotypes. The mating type exerted the strongest influence. Under reciprocal combinations (♂ black × ♀ grey and ♂ grey × ♀ black), paternal inheritance demonstrated greater stability. In the first combination, paternal dominance in the expression of the black coat reached 3.2% (51.6%), whereas in the second combination paternal influence toward grey coat expression was 6.8% (53.4%) (Baibekov and Baibekov, 2016; Baibekov, 2018).

An evaluation of coat color inheritance under various mating combinations showed that the highest proportion of jacket-type fur (84.4%) was obtained through homogeneous matings of black-coated parents.

In heterogeneous matings (♂ black × ♀ grey and ♂ grey × ♀ black), the proportion of jacket-type lambs ranged from 46.1% to 75.3%, while the lowest proportion (46.1%) was observed in the mating scheme “black × grey (silvery shade)” (Ombayev et al., 2019).

A study of hereditary traits in grey sheep with silvery coloration demonstrated that the inheritance of the desirable silvery shade varied depending on mating type. Under heterogeneous mating (♀ black × ♂ grey), 54.8% of offspring inherited the silvery shade; under the reciprocal combination (♂ grey × ♀ black), the proportion was 53.7%. In homogeneous mating “grey × grey,” inheritance of silvery coloration reached 72% (Parzhanov et al., 2018).

Data obtained by Baibekov et al. (2014) indicate that both the mating scheme (♂ grey × ♀ black) and the proportion of white fibers have a substantial effect on inheritance of fur types. The use of black rams when mating grey ewes results in a high proportion of jacket-type lambs – 65.8% and 64.4%, respectively – significantly surpassing other fur types in qualitative traits. Under these heterogeneous combinations, the frequency of silvery coloration ranged from 47.9% to 61.4%. The highest occurrence of silvery coloration (61.4%) was observed among offspring of rams with a high proportion of white fibers (WFR = 69-71%) in the combination “♂ grey × ♀ black.”

In a study analyzing index-based selection for uniformity of grey coloration in Karakul sheep, the highest proportion of elite-class lambs (34.6%) was obtained from sires with a Grey Color Uniformity Index (GCU index) of 0.16%. This exceeded the result obtained from rams with a GCU index of 0.28 by 10.2% (24.4%).

In the same offspring group, the proportion of second-class lambs remained low at 9.2%.

In the second group (GCU index = 0.17-0.28), the proportion of elite-class lambs reached 31.0%, while the share of second-class lambs was 12.9%. The proportion of elite lambs in this group exceeded the flock average by 6.6% and the proportion of second-class lambs by 13.9% (Aralbayev and Dzhumabayev, 2011; Baibekov et al., 2011).

An evaluation of color expression in lambs showed that under homogeneous mating, the proportion of offspring with distinctly expressed coloration reached 32.0%, which was 8.0% higher than under heterogeneous mating. At the same time, the proportion of lambs with insufficient color expression remained relatively low – 14.1%. The fold (curl) length in lambs from homogeneous mating exceeded that of heterogeneous offspring by 3.9%, reaching 57.4%.

An analysis of curl retention in grey lambs with age demonstrated that the highest retention level (55.7%) was observed under homogeneous mating. Under heterogeneous mating, this indicator declined slightly to 52.4% (Ombaev et al., 2012).

Azhibekov and Karynbayev (2013) noted that no statistically significant differences were found between homogeneous and heterogeneous mating outcomes among offspring of rams with different WFR indices. At the same time, the proportion of lambs exhibiting the desirable bluish shade ranged from 20.8% to 24.1%.

When grey rams of bluish coloration were used with black ewes, 60.7% of offspring inherited the bluish shade, whereas under the reciprocal mating combination, this proportion was 52.8% (Azhibekov and Karynbayev, 2013).

1. From an economic standpoint, the use of the traditional heterogeneous mating schemes (♂ grey × ♀ black; ♂ black × ♀ grey) is considered optimal. Under these combinations, the inheritance ratio of coat colors averages 50% grey and 50% black, and the resulting grey lambs are heterozygous rather than albino. It has been established that inheritance of grey and black coat colors in such mating combinations maintains a balanced distribution (Alibayev et al., 2014; Azhimetov et al., 2020) (Figure 1).

   

   Figure 1
   Research scheme.
   

2. Materials and Methods

The study material consisted of black Karakul ewes and grey Karakul rams (both local and imported) exhibiting silvery and bluish shades of the jacket-type fur. The experimental component of the research was carried out at the base farms of “OtyrarAgro” LLP (Otyrar district) and “Narmet” farm (Sauran district) in the Turkestan region of the Republic of Kazakhstan.

The experimental population included purebred black and grey Karakul sheep of the jacket-type fur, comprising 897 ewes aged 3.0-3.5 years and 4 stud rams. All rams used in the study met the requirements for animals of the elite breeding class.

The number of inseminated ewes per mating scheme was as follows (heads): I – 224; II – 213; III – 218; IV – 242.

Artificial insemination of the breeding flock was performed in early October 2024 and lasted 25 days. The gestation period ranged from 148 to 152 days, and mass lambing occurred between 15 March and 5 April 2025. All insemination procedures were conducted in accordance with official guidelines (Russia, 1967).

Animals were maintained under a pasture-based system, supplemented with concentrates during the second half of gestation (7-8 weeks), at a rate of 250 g per day.

Evaluation of fur quality parameters and classification (bonitation) of lambs was performed in accordance with the approved “Instructions for the evaluation of Karakul lambs” (Russia, 2014).

The breeding condition of ewes prior to mating was distributed as follows: high – 88.9%, medium – 10.1%, low – 1.0%. These indicators positively influenced ewe reproductive performance, which reached 96.7%.

Primary numerical data obtained in the study were processed using methods of variation statistics (Yakovenko et al., 2013).

All experimental procedures involving animals complied with international animal welfare principles and were approved by the Shymkent University Bioethics Committee (Protocol Nº 03, dated 15 September 2024).

3. Results and Discussion

One of the key indicators of breeding efficiency in Karakul sheep production is the selection of parental pairs capable of producing offspring with the desired fur pattern. Although aesthetic preferences may change over time, the jacket-type fur has consistently been regarded by specialists as one of the most valuable. Its main advantages include the clearly defined symmetrical curl pattern and the uniformity of the primary traits characterizing the quality of the hair coat.

The fur type represents a combination of quantitative traits (curl length and width) and qualitative traits (silkiness, luster, curl pattern, etc.) distributed across the entire skin surface. The distribution of grey lambs across fur types depending on the mating scheme is presented in Table 1.

Table 1
Inheritance of breeding traits in progeny under different mating schemes.

Indicator	Mating schemes
	I	II	III	IV
	♂Stud rams with grey coloration, uniform silvery shade, jacket-type fur (local)	♂Stud rams with grey coloration, uniform silvery shade, jacket-type fur (imported)	♂Stud rams with grey coloration, uniform bluish shade, jacket-type fur (local)	♂Stud rams with grey coloration, uniform bluish shade, jacket-type fur (imported)
	♀Ewes with black coloration, jacket-type fur
Number of lambs, head	217	208	215	227
Coloration, %
Black, head	112	106	107	117
%	51.6±0.85	51.0±0.41	49.8±0.25	51.5±0.42
Grey, head	105	102	108	110
%	48.4±0.44	49.0±0.35	50.2±0.53	48.5±0.43
incl. silvery	55	62	17	18
%	52.4±0.56	60.8±26	15.7±0.29	16.4±0.23
Bluish	21	28	63	67
%	20.0±0.39	27.4±0.34	58.3±0.44	60.9±0.52
Other	29	12	28	25
%	27.6±0.26	11.8±0.12	25.9±0.42	22.7±0.23
Fur type
jacket-type	55.8±0.45	63.0±0.44	50.7±0.48	59.0±0.41
ribbed	6.4±0.21	9.1±0.32	9.8±0.36	10.6±0.37
flat	2.8±0.32	3.9±0.37	6.5±0.52	5.3±0.54
Caucasian	35.0±0.15	24.0±0.11	33.0±0.18	25.1±0.26
Lamb grading
elite	27.6±0.31	30.8±0.38	27.0±0.52	32.6±0.39
class I	52.5±0.39	54.8±0.45	53.5±0.42	55.9±0.41
elite + class I	80.1±0.24	85.6±0.22	80.5±0.31	88.5±0.29
class II	19.9±0.16	14.4±0.10	19.5±0.14	11.5±0.11
Curl length
long (>40 mm)	12.4±0.53	14.4±0.54	13.5±0.52	16.3±0.33
medium (20-40 mm)	65.4±0.19	70.7±0.30	63.3±0.34	71.4±0.35
short (<20 mm)	22.2±0.21	14.9±0.15	23.2±0.19	12.3±0.23
Curl width
fine (<4.0 mm)	9.7±0.12	13.0±0.16	9.3±0.11	11.0±0.13
medium (4-8 mm)	72.4±0.23	76.0±0.33	81.4±0.28	76.7±0.26
large (>8 mm)	17.9±0.17	11.0±0.16	9.3±0.21	12.3±0.18
Curl pattern
parallel concentric	53.9±0.54	58.2±0.53	52.6±0.42	60.8±0.47
parallel straight	8.8±0.12	9.6±0.22	9.3±0.23	8.8±0.13
undefined/mixed	37.3±0.31	32.2±0.27	38.1±0.16	30.4±0.35
Hair silkiness
strong	36.9±0.34	41.3±0.44	37.7±0.39	43.2±0.37
normal	48.8±0.32	46.2±0.36	49.3±0.21	49.8±0.34
insufficient	14.3±0.10	12.5±0.15	13.0±0.14	7.0±0.15
Hair luster
strong	36.9±0.51	42.8±0.47	38.6±0.46	41.4±0.39
normal	48.4±0.45	48.6±0.41	49.3±0.37	49.8±0.33
insufficient	14.7±0.22	8.6±0.24	12.1±0.21	8.8±0.25

A comparative analysis of offspring obtained from local (Kazakhstani) and imported (Uzbekistani) stud rams of grey coloration with a silvery shade showed that the average proportion of lambs with the jacket-type fur was 55.8% and 63.0%, respectively. The highest inheritance of the jacket-type fur was observed in the progeny of imported stud rams, reaching 63.0%, with a difference of 7.2% (P>0.999) in their favor.

An analysis of offspring obtained from local and imported stud rams of grey coloration with a bluish shade revealed that the average proportion of jacket-type lambs amounted to 50.7% and 59.0%, respectively. The superior inheritance rate of the jacket-type was again observed in the offspring of imported stud rams (59.0%), with a difference of 8.3% (P>0.999).

Based on a comprehensive analysis of selection traits and considering their breeding value, lambs were classified into quality classes. The proportion of lambs assigned to the elite and first class among the offspring of local and imported grey stud rams with silvery fur was 80.1% and 85.6%, respectively, with a difference of 5.5% (P>0.99).

In the groups sired by grey stud rams with bluish fur, the corresponding proportions were 80.5% and 88.5%, with an average difference of 8.0% (P>0.999).

In heterogeneous matings of local grey stud rams with silvery fur to black ewes, the offspring coat color distribution was 51.6% black and 48.4% grey. Similar results were obtained with imported silvery-grey stud rams, with 51.0% black and 49.0% grey, maintaining a 1:1 ratio.

For heterogeneous matings involving bluish-grey stud rams and black ewes, the distribution was 51.6% black and 48.4% grey, further confirming the consistent 50:50 ratio of grey to black lambs.

A comparative analysis of offspring from local and imported silvery-grey stud rams indicated that the average proportion of silvery-shaded lambs was 52.4% and 60.8%, respectively, with a difference of 8.4% (P>0.999).

For bluish-grey rams, the corresponding values were 58.3% and 60.9%, with a difference of 8.4% (P>0.999). The inheritance of the jacket-type fur was higher among progeny of imported rams (59.0%), with a difference of 2.3% (P>0.99).

One of the most important qualities of Karakul fur is its curl pattern, determined by the arrangement of curls. Despite its significance, this trait often receives insufficient attention from breeders. The curl pattern in Karakul fur is formed by the consistent arrangement of spiral and other curl types across the skin, always producing a characteristic, breed-specific design or ornament.

In the first mating scheme, where a local silvery-grey stud ram was used, the proportion of lambs exhibiting the desirable parallel-concentric curl pattern was 60.1%. In the second scheme, with an imported silvery-grey stud ram, this proportion reached 61.9%. In the third and fourth schemes, where local and imported bluish-grey stud rams were used, the proportion of lambs with the desired parallel-concentric pattern was 58.3% and 60.9%, respectively.

Across all mating schemes, the proportion of lambs with the parallel-linear pattern ranged from 4.6% to 4.9%, while lambs exhibiting the undesirable mixed pattern accounted for 33.5% to 35.0%.

The analysis indicates that both the arrangement and size of curls are heritable traits. These characteristics are closely associated with other fur quality parameters in Karakul sheep and therefore must be considered when selecting lambs for breeding purposes.

Grey lambs exhibited high-quality fur traits, particularly in terms of silkiness and luster. In the first mating scheme, involving a local grey stud ram with uniform silvery coloration, 44.0% of lambs displayed strongly silky hair, 48.1% had normally silky hair, and the proportion of lambs with strong and normal fur luster was 44.9% and 45.7%, respectively. In the second scheme, using an imported grey stud ram with uniform silvery coloration, the proportion of lambs with strongly silky hair was 43.2%, normally silky 49.2%, and those with strong and normal fur luster were 44.9% and 49.6%, respectively. In the third scheme, involving a local grey stud ram with uniform bluish coloration, strongly silky hair was observed in 43.2% of lambs, normally silky in 49.2%, and strong and normal luster in 44.9% and 49.6%, respectively. Similar results were observed in the fourth scheme, with the offspring of an imported bluish grey stud ram, showing 43.2% strongly silky, 49.2% normally silky, and 44.9% and 49.6% with strong and normal luster, respectively.

Considering the importance of white and black fiber composition, as well as the predominance of white fiber length, we analyzed the frequency of grey lambs with different fiber traits in both silvery and bluish shades. Lambs of silvery and bluish grey coloration, obtained from both local and imported stud rams, were classified based on white fiber content into three groups: low (65.0-67.9%), medium (68.0-71.9%), and high (72.0-75.9%), and based on excessive white fiber length into short (20.0-21.9%), medium (22.0-23.9%), and long (24.0-25.9%) (Table 2).

Table 2
Frequency of grey lambs with silvery and bluish shades by fiber color traits.

White fiber content (%)		n	%	Excessive white fiber length (%)		n	%
I – Silvery, local
65-67.9	low	14	25.5	20-21.9	short	13	23.6
68-71.9	medium	24	43.6	22-23.9	medium	31	56.4
72-75.9	high	17	30.9	24-25.9	long	11	20.0
Total:		55	100.0	Total:		55	100.0
II – Silvery. imported
65-67.9	low	15	24.2	20-21.9	short	13	21.0
68-71.9	medium	29	46.8	22-23.9	medium	35	56.4
72-75.9	high	18	29.0	24-25.9	long	14	22.6
Total:		62	100.0	Total:		62	100.0
III – Bluish. local
65-67.9	low	16	25.4	20-21.9	short	13	20.6
68-71.9	medium	29	46.0	22-23.9	medium	35	55.6
72-75.9	high	18	28.6	24-25.9	long	15	23.8
Total:		63	100.0	Total:		63	100.0
IV – Bluish. imported
65-67.9	low	16	23.9	20-21.9	short	13	19.4
68-71.9	medium	33	49.2	22-23.9	medium	39	58.2
72-75.9	high	18	26.9	24-25.9	long	15	22.4
Total:		67	100.0	Total:		67	100.0

Regarding the bluish shade, the distribution of lambs according to white fiber content was as follows: low – 25.4%, medium – 46.0%, and high – 28.6% for offspring of local stud rams, and 23.9%, 49.2%, and 26.9% for offspring of imported stud rams.

A highly significant genetic correlation was found between white fiber content and the degree of excessive fiber length (P<0.001). Therefore, the selection of grey lambs with silvery or bluish shades and their use in breeding programs is a critical measure for improving the efficiency of selection in grey Karakul sheep.

Color uniformity is one of the primary coat traits influencing fur quality and plays a pivotal role in the selection of grey lambs.

In this context, we studied the effect of both the proportion and excessive length of white fibers on the uniformity of grey coloration. Table 3 presents data on uniformity of grey coloration depending on the ratio of white to black fibers and fiber length.

Table 3
Uniformity of grey coat color depending on white fiber content and excessive white fiber length in %.

White fiber content	Excessive white fiber length	Number of lambs	Uniformity
			excellent	good	insufficient
I – Silvery, local
Low (65.0-67.9%)	short	6	16.7	33.3	50.0
	medium	7	14.3	57.1	28.6
	long	1	-	-	100.0
Average		14	14.3	42.9	42.9
Medium (68.0-71.9%)	short	6	16.7	33.3	50.0
	medium	10	30.0	60.0	10.0
	long	8	12.5	37.5	50.0
Average		24	20.8	45.8	33.4
High (72.0-75.9%)	short	5	-	60.0	40.0
	medium	9	11.1	55.6	33.3
	long	3	-	33.3	66.7
Average		17	5.9	52.9	41.2
Total:		55	14.5	47.3	38.2
III – Bluish, local
Low (65.0-67.9%)	short	6	16.7	33.3	50.0
	medium	8	12.5	50.0	37.5
	long	1	-	-	100.0
Average		15	13.3	40.0	46.7
Medium (68.0-71.9%)	short	7	14.2	42.9	42.9
	medium	15	40.0	53.3	6.7
	long	8	12.5	37.5	50.0
Average		30	26.7	46.7	26.6
High (72.0-75.9%)	short	4	-	50.0	50.0
	medium	10	10.0	50.0	40.0
	long	3	-	33.3	66.7
Average		17	5.9	47.1	47.0
Total:		62	17.7	45.2	37.1
II – Silvery, imported
Low (65.0-67.9%)	short	5	20.0	60.0	20.0
	medium	9	22.2	66.7	11.1
	long	1	-	100.0	-
Average		15	20.0	66.7	13.3
Medium (68.0-71.9%)	short	8	12.5	50.0	37.5
	medium	16	31.2	62.5	6.3
	long	6	33.3	50.0	16.7
Average		30	26.7	56.7	16.6
High (72.0-75.9%)	short	7	28.6	57.1	12.3
	medium	10	30.0	60.0	10.0
	long	1	-	100.0	-
Average		18	27.8	61.1	11.1
Total:		63	25.4	60.3	14.3
IV – Bluish, imported
Low (65.0-67.9%)	short	5	20.0	40.0	40.0
	medium	10	20.0	30.0	50.0
	long	1	-	100.0	-
Average		16	18.8	37.5	43.7
Medium (68.0-71.9%)	short	8	25.0	62.5	12.5
	medium	19	10.5	84.2	5.3
	long	6	33.3	50.0	16.7
Average		33	18.2	72.7	9.1
High (72.0-75.9%)	short	3	33.3	66.7	-
	medium	11	27.3	54.5	18.2
	long	4	50.0	50.0	-
Average		18	33.3	55.6	11.1
Total:		67	22.4	59.7	17.9

For lambs with silvery shade, the ratio and length of white fibers had a substantial effect on coat uniformity (Table 3). The white fiber content ranged between 68.0% and 71.9%. The highest uniformity based on white fiber content was observed in silvery grey lambs in Variant I (90.0%). In Variant II, the uniformity of silvery grey lambs reached 93.7%. In Variant I, the proportion of lambs with excellent, good, and insufficient uniformity was 14.5%, 47.3%, and 38.2%, respectively. In Variant II, the corresponding values were 25.4%, 60.3%, and 14.3%. Thus, the qualitative characteristics of lambs in Variant II were somewhat superior in terms of uniformity.

Comparable results for the bluish shade in offspring were as follows: Variant III – 93.3%, Variant IV – 94.7%. Analysis of uniformity in bluish grey lambs showed that in Variant III, the proportions of excellent, good, and insufficient uniformity were 17.7%, 45.2%, and 37.1%, respectively, whereas in Variant IV, these values were 22.4%, 59.7%, and 17.9%, respectively.

Calculation of correlation coefficients was performed to determine the relationships between the studied traits and environmental factors. Data on the strength of associations between the traits of silvery and bluish fur coloration are presented in Table 4.

Table 4
Correlation coefficients between traits.

Traits	r±mr	P
I – Silvery, local
Uniformity	0.197±0.065	<0.001
Expression	0.298±0.059	<0.001
II – Silvery, imported
Uniformity	0.199±0.062	<0.001
Expression	0.303±0.077	<0.001
III – Bluish, local
Uniformity	0.195±0.051	<0.001
Expression	0.301±0.059	<0.001
IV – Bluish, imported
Uniformity	0.202±0.061	<0.001
Expression	0.305±0.067	<0.001

As shown in Table 4, correlation coefficients between white fiber traits and the uniformity and expression of silvery and bluish shades in grey lambs were positive and highly significant (P<0.001). The offspring of local stud rams exhibited slightly lower correlation values compared to those of imported rams. Differences in uniformity of silvery shade between offspring of local and imported rams were minimal and fell within the margin of error. For bluish coloration, differences in uniformity and expression between the groups were also minor, ranging from 1.3% to 3.5%.

The effect of white fiber content and excessive fiber length on the quality of silvery and bluish coloration in offspring of local and imported rams is summarized in Table 5.

Table 5
Influence of white fiber content and excessive fiber length on the quality of silvery and bluish shades in offspring of local and imported stud rams.

Shade	Traits	Correlation (r)	Р	Magnitude of Effect
Silvery	Variant I
	White fiber content
	Uniformity	0.104±0.007	<0.001	8.1 – 12.6%
	Expression	0.288±0.003	<0.001	25.7 – 28.8%
	Excessive white fiber length
	Uniformity	0.109±0.008	<0.001	9.2 – 12.3%
	Expression	0.336±0.004	<0.001	32.6 – 35.3%
	Variant II
	White fiber content
	Uniformity	0.111±0.006	<0.001	8.3 – 13.9%
	Expression	0.289±0.004	<0.001	26.2 – 30.8%
	Excessive white fiber length
	Uniformity	0.113±0.006	<0.001	9.4 – 13.7%
	Expression	0.342±0.005	<0.001	33.1 – 37.1%
Bluish	Variant III
	White fiber content
	Uniformity	0.105±0.006	<0.001	7.9 – 12.1%
	Expression	0.289±0.004	<0.001	23.7 – 26.7%
	Excessive white fiber length
	Uniformity	0.107±0.006	<0.001	9.0 – 12.4%
	Expression	0.337±0.003	<0.001	32.9 – 36.4%
	Variant IV
	White fiber content
	Uniformity	0.110±0.007	<0.001	8.6 – 13.6%
	Expression	0.291±0.005	<0.001	26.5 – 28.9%
	Excessive white fiber length
	Uniformity	0.112±0.007	<0.001	9.8 – 13.9%
	Expression	0.339±0.005	<0.001	34.5 – 37.3%

Analysis of traits determining the quality of silvery fur in both mating variants yielded the following results. In the progeny of local stud rams, the correlation of white fiber content with uniformity and expression was highly significant (r=0.104±0.007, P<0.001), with effect sizes ranging from 8.1-12.6% for uniformity and 25.7-28.8% for expression. The correlation between excessive white fiber length and uniformity/expression was r=0.109±0.008, P<0.001 and r=0.336±0.004, P<0.001, respectively. In the offspring of imported stud rams, the corresponding correlations were: white fiber content versus uniformity/expression: r=0.111±0.006, P<0.001; excessive white fiber length versus uniformity/expression: r=0.113±0.006, P<0.001 and r=0.342±0.005, P<0.001. Effect sizes ranged from 9.4-13.7% for uniformity and 33.1-37.1% for expression.

As noted above, in evaluating the qualitative parameters of silvery fur, particular attention was paid to the ratio and content of white fibers and their influence on uniformity and expression, as well as the degree of correlation. Analysis of similar parameters for bluish fur yielded the results presented in Table 5 . Regarding uniformity, expression, white fiber content, and excessive fiber length, the offspring of imported rams performed slightly better. Correlation coefficients in both groups were high and statistically significant: r = 0.105 ± 0.006, P < 0.001 for uniformity; r = 0.289 ± 0.004, P < 0.001 for expression in the progeny of local rams; r = 0.110 ± 0.007, P < 0.001 for uniformity; r = 0.291 ± 0.005, P < 0.001 for expression in the progeny of imported rams.

4. Conclusion

The study demonstrated that, across all mating schemes, the proportion of lambs with the jacket-type fur was virtually identical.

Uniformity of coloration in silvery-shaded lambs was significantly influenced by the ratio and length of white to black fibers. A comparative analysis of uniformity parameters (based on white fiber content) between offspring of local and imported stud rams indicated a slight advantage of imported stud rams across all primary traits.

In the first mating scheme, 64.2% of the offspring inherited the silvery shade, while in the second scheme, the proportion was 66.7%.

In studies on the inheritance of bluish shade, where local grey stud rams (variant III) and imported rams (variant IV) were mated to black ewes, 58.3% and 60.9% of the offspring, respectively, inherited the bluish shade.

These results confirm that the desirable silvery and bluish shades exhibit high levels of expression and uniformity, contributing to the commercial and breeding value of grey Karakul sheep.

Regarding uniformity, expression, white fiber content, and excessive fiber length, the offspring of imported rams performed slightly better. Correlation coefficients in both groups were high and statistically significant: r = 0.105 ± 0.006, P < 0.001 for uniformity; r = 0.289 ± 0.004, P < 0.001 for expression in the progeny of local rams; r = 0.110 ± 0.007, P < 0.001 for uniformity; r = 0.291 ± 0.005, P < 0.001 for expression in the progeny of imported rams.

Inheritance of the desirable parallel-concentric curl pattern was nearly identical across all mating schemes, with minor differences within the margin of error.

Both the arrangement and size of curls are heritable traits, closely associated with other fur quality characteristics of Karakul sheep. Therefore, these traits should be taken into account when selecting lambs for breeding purposes.

Acknowledgements

This research has been funded by the Ministry of Agriculture of the Republic of Kazakhstan (Grant No. BR22885692 «Development modern selectional-technological and molecular-genetic methods for improving, preserving and rationally using genetic resources sheep the different areas of productivity»)

Data Availability Statement

The entire data set that supports the results of this study will be published in the article itself.

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Edited by

• Editor:
  Takako Matsumura Tundisi

Publication Dates

• Publication in this collection
  17 Apr 2026
• Date of issue
  2026

History

• Received
  28 Aug 2025
• Accepted
  13 Feb 2026