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Article

Growth Dynamics of Lithuanian Blackface Lambs: Role of Crossbreeding with German Blackheaded Mutton Rams, Sex and Seasonality

by
Rūta Šveistienė
* and
Violeta Razmaitė
Department of Animal Breeding and Reproduction, Animal Science Institute, Lithuanian University of Health Sciences, R. Žebenkos 12, LT-82317 Baisogala, Lithuania
*
Author to whom correspondence should be addressed.
Agriculture 2025, 15(1), 31; https://doi.org/10.3390/agriculture15010031
Submission received: 25 November 2024 / Revised: 17 December 2024 / Accepted: 19 December 2024 / Published: 26 December 2024
(This article belongs to the Special Issue Productivity and Efficiency of Agricultural and Livestock Systems)
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Abstract

Crossbreeding is widely used to improve livestock performance, combining favorable breed traits through additive effects while maintaining genetic diversity. This approach enhances sheep farming economic sustainability to improve reproduction timing and prolificacy. Optimizing litter size is crucial for maximizing lamb production under diverse conditions, and breeding programs worldwide focus on both within-breed selection and crossbreeding strategies. This study aimed to evaluate the effects of the controlled introgression of German Blackheaded Mutton (GBM) rams on ewe prolificacy and lamb growth while preserving breed structure and integrity. The study examined the effects of genotype, litter size, season, and sex on lamb birth weight and growth. Genotype significantly influenced birth weight (p < 0.01), with crossbreeds containing 6.25% GBM having the highest weights, though higher GBM proportions had no additional benefit. Crossbred lambs outperformed purebred Lithuanian Blackface (LBF) lambs at all measured ages. Litter size significantly affected birth weight (p < 0.001) and growth, with larger litters leading to lighter lambs. Seasonal effects were notable only at three months, with winter-born lambs weighing 2.45 kg more than spring-born lambs (p < 0.010). Most lambings occurred in winter (71.4%). Male lambs were heavier than females at eight months (3.45 kg difference, p < 0.010). Genotype–season interactions influenced weights at several ages, with winter-born purebred LBFs and certain crossbreeds generally outperforming their spring-born counterparts. Lambs from single-lamb litters were consistently heavier, especially in winter and summer. These findings emphasize the interplay of genetics, season, and litter size on lamb growth.

1. Introduction

The Lithuanian Blackface (LBF) sheep breed, established in the mid-20th century, was developed by crossbreeding local sheep with Shropshire and German Blackheaded Mutton rams, combined with selective breeding to enhance traits such as wool quality, meat yield, and adaptability to Lithuania’s climatic and farming conditions [1]. The breeding strategy aimed to achieve a balance between productivity and resilience to local environmental challenges. Significant milestones in the development of the Lithuanian Blackface included the establishment of dedicated breeding farms, such as those in Pasvalys (1952) and Telšiai (1956), which played a critical role in maintaining genetic stability and implementing controlled selection. The breed was officially recognized in 1961 as a semi-fine-wooled, meat–wool-type sheep [2]. Recent analyses using SNP molecular markers have demonstrated that Lithuanian Blackface sheep genetically cluster between German and British breeds, reflecting their composite origins [3]. This breed is characterized by favorable production traits, including good carcass yield (approximately 45–48%), high-quality wool, and moderate milk production capacity [4]. These attributes underscore its suitability for the dual-purpose meat and wool production systems typical of Lithuanian agriculture.
Currently, it represents the largest (65%) sheep population in Lithuania. According to the data provided by the information service for animal husbandry and breeding in Lithuania (ŪGVIS stud book report), the number of purebred Lithuanian Blackface sheep amounts to 7523, comprising 93% of the main chapter of the stud book. In comparison, in 2013, there were only 4226 sheep [5]. Lithuanian Blackface sheep are still popular among breeders and have an effective population size with a “no longer vulnerable” risk status. Selection programs for Lithuanian Blackface sheep have been officially approved [2]. The population of Lithuanian Blackface sheep has a breeding nucleus maintained by the Šeduva Experimental Farm (now, it belongs to the UAB Genetiniai Ištekliai), which was founded in 1963 and furthered research into this breed, focusing on aspects like milk composition, wool quality, and overall health, solidifying its status as a valuable genetic resource for Lithuania. This nucleus is supported through the Lithuanian Endangered Farm Animal Genetic Resources Conservation Program and funded by the Ministry of Agriculture of the Republic of Lithuania because Lithuanian Blackface sheep are considered a valuable heritage breed with acknowledged genetic and cultural importance [6]. Despite an overall decrease in sheep farming, the breed remains popular in Lithuania, especially due to its resilience and suitability for both wool and meat production under local farm conditions. Although Lithuanian Blackface sheep are prized for their productivity, especially in terms of lamb yield (1.3 lambs per year) and growth rates (106 g/per day until 12 month) [7], there is a position which addresses the need for improved farm resilience and economic sustainability by incorporating breeding techniques that align with global production demands and support income stability in sheep farming.
Different literature sources show that crossbreeding has been used extensively for livestock genetic improvement, leading to improved performance traits [8]. This approach enables livestock farmers to increase the production of animal products while maintaining genetic diversity [9]. It can lead to a combination of favorable breed traits based on the direct additive breed effect and heterosis effect [10]. Lithuanian Blackface sheep were crossbred with German Blackheaded Mutton rams to enhance meat quality and increase productivity without compromising the breed’s structural integrity, and 500 GBM sheep were imported during 1925–1941 [2]. This strategic crossbreeding has helped improve resistance to local environmental factors and supported commercial viability for sheep farmers in Lithuania, addressing challenges in feed efficiency and meat quality. Lithuanian breeders also emphasize selecting traits that boost meat yield and resilience, which are essential for adapting to the local climate and farming conditions [11].
The use of high-performance breeds to produce crosses indistinguishable from the local breed is not recommended due to the risk of unintentionally introducing exotic genotypes into the local breed. However, to expand the genealogical structure using local females and, when it is necessary, to ensure the maintenance of viable populations of the local breed, temporary crossbreeding may be permissible. To enhance the genealogical structure of the Lithuanian Blackface sheep selection nucleus, a decision was made to establish a new male line through temporary crossbreeding with German Blackheaded Mutton rams, aiming to improve the productivity of sheep.
Reproduction ability and the timing of reproduction has important impacts on the prolificacy and development of sheep farming [12,13,14,15]. The number of born lambs, especially the longevity of ewes, play a major role in the economics of sheep production. The German Blackheaded Mutton breed was characterized by a positive length of productive life [16].
Moreover, sheep production occurs under a wide range of conditions, and there are limiting factors for lamb production [17]. Breeding programs to improve prolificacy in sheep have been launched in various countries both for within-breed selection and the introgression of other breeds; therefore, the definition of the optimal litter size is of considerable importance [17].
The aim of this study was to examine the effects of the controlled introgression of German Blackheaded Mutton rams on ewe prolificacy and lamb growth in the Lithuanian Blackface sheep breed while preserving breed structure and integrity.

2. Materials and Methods

This study was approved by the Institutional Board of the Animal Science Institute of the Lithuanian University of Health Sciences (protocol No 24/01/30/01) on 30 January 2024.
All records were collected from the data register routinely gathered and maintained at the UAB “Genetiniai Ištekliai”. This farm keeps Lithuanian Blackface sheep (LBF) and is developing a new sire line through the introgression of German Blackheaded Mutton (GBM). The animals used for the analysis were purebred Lithuanian Blackface sheep (the LBF breed was presented in 4 generations) and their crossbreeds, with 6.25%, 12.5%, 25% and 50% of German Blackheaded Mutton blood. Records of the prolificacy (number of lambs born per ewe lambing) of 5486 ewes and their lamb weights between 2018 and 2023 were used in this study. The lambs were weighed at birth and the sex of each lamb was recorded. The weight of lambs was also recorded at birth and at 2, 3, 4, 8, and 12 months.
According to the agro-climatic conditions, two types of feeding systems were utilized: indoor feeding and pasture-based feeding. The pasture-based period lasts from mid-May to early November, while the indoor feeding period spans from late November to early May. During the indoor feeding period, the ration for all lambs consists of hay (1 kg), haylage (1 kg), home-produced concentrated feed (0.3–0.4 kg), and mineral licks. The pasture-based diet comprises fresh grass ad libitum, water, and mineral licks. Lambs are weaned at 4 months of age, and prior to weaning, ewes with their offspring are kept indoors. During this period, lambs receive additional compound feed containing 18–19% crude protein, with the allocated amount of concentrated feed ranging from 0.1 to 0.2 kg per lamb, depending on age. After weaning, female lambs are pastured on cultivated pastures, while weaned ram lambs are kept indoors continuously. The indoor feeding ration includes hay, haylage and 0.3–0.4 kg per animal of concentrated feed, which consists of a pea–oat–vetch mixture, barley, and protein supplements.
The data were subjected to an analysis of variance via a general linear (GLM) procedure in IBM SPSS Statistics 29 for Windows, Version 29 Armonk, NY, USA: IBM Corp software, with LSD tests to determine the significance of differences in the estimated marginal (EM) means between the groups. The GLM model included the fixed factors of the genotype group (purebred Lithuanian Blackface sheep and 6.25%, 12.5%, 25%, and 50% proportions of German Blackheaded Mutton, lambing season, and lamb sex) and factor interactions (genotype × litter size; genotype × sex; genotype × season; and season × litter size). The differences were regarded as significant when p < 0.05.

3. Results

Most of the lambs from all genotype groups included in the analysis were single-born (Table 1). The highest proportion of twins were born in purebred LBF litters. Moreover, triplets were also born in purebred LBF litters, and this demonstrated higher (p < 0.001) prolificacy (1.5 lamb in the litter) of the LBF sheep breed compared with crossbreeds (1.27–1.39 lambs). Three lambs in the LBF litters showed lower birth weight (p < 0.001) by 0.4 kg and 0.6 kg, and demonstrated lower weight during growth. Therefore, triplets were excluded from further analysis.
Genotype showed an effect (p < 0.01) on lamb birth weight (Table 2). The highest lamb birth weight was found in the crossbred group with 6.25% German Blackheaded Mutton (GBM); however, higher GBM in sheep showed no association with an increase in lamb birth weight. Sheep genotype also affected the growth of lambs. A higher weight of crossbred lambs was detected at eight and twelve months of age compared to purebred Lithuanian Blackface (LBF) lambs. GBM introgression in LBF appeared to affect (p < 0.001) the average daily gain (ADG0) from lamb birth to twelve months of age. Crossbred lambs with 6.25% GBM demonstrated 28.7% higher ADG (147 g) compared with purebred LBF (114.2 g). However, a GBM increase in LBF lambs was associated with an ADG difference decrease between LBF lambs and crossbreeds. Crossbreeds with 12.5% GBM, 25% GBM, and 50% GBM had 126.2 g, 123.3 g, and only 115.7 g of ADG, respectively. Lamb weight was affected by litter size at birth and at two months of age. Twins at birth had a 0.4 kg lower (p < 0.001) weight, and at two months of age a 2 kg lower (p < 0.05) weight, compared with single lambs in a litter.
Most ewes (71.4%) lambed once per year in winter (December–February), 27.3% of lambings occurred in spring (March–May), 1.1% occurred in summer, and only 2 occurred (0.04%) in autumn. There were no differences in the weight of lambs born in different seasons except for the lambs at three months of age (Table 3). The lambs born in winter were 1.8 kg heavier (p < 0.010) at three months of age than the lambs born in spring. Sex appeared to have an effect only at the age of eight months, when the weight difference between males and females increased (p < 0.001) to 3.6 kg.
There were significant interactions (p < 0.010 and p < 0.05) concerning the weight at eight months of age between lamb genotype and sex and between lambing season and sex, respectively (Table 4). Purebred LBF males showed a 6.8 kg higher weight, and crossbred ones with 12.5% GBH to 50% GBH demonstrated a 2.6 kg to 5.3 kg higher weight compared with females; however, 6.25% GBH crossbred males showed a 1.5 kg lower weight than females. Males born in winter, spring, and summer at eight months of age were 4.3 kg, 2.9 kg, and 3 kg heavier compared with females, respectively.
A significant interaction (p < 0.05) between season and litter size was found only at the third month of age (Table 4). Lambs from litters of one born in winter and summer were 2.8 kg and 3.1 kg heavier, respectively, than lambs from litters of two. However, lambs born in spring in litters of two showed a slightly higher weight than lambs from litters of one.
There were also significant interactions (p < 0.05) between the genotype and season during lamb growth at three, four, and twelve months of age. Purebred LBF lambs born in winter at four and twelve months of age had a higher weight than the animals born in spring; however, at four months of age, crossbred lambs born in winter had a lower weight than the lambs born in spring (Figure 1). At twelve months of age, a higher live weight was demonstrated not only in purebred LBF lambs but also in crossbred lambs, except crossbreeds with 25% GBH born in winter compared with animals born in spring.
There were significant interactions (p < 0.010) concerning weight at eight months of age between lamb genotype and sex (where 6.25% GBH crossbred females showed a 1.5 kg higher weight than males, whereas females in other all groups had a lower live weight compared with males) and between lambing season and sex (Figure 2).

4. Discussion

The Lithuanian Blackface (LBF) sheep breed was initially improved using German Blackheaded Mutton (GBM) in 1961, followed by experimental improvement with Latvian Dark-Headed (LDH) rams during 1984–1988. However, these efforts did not yield statistically significant results [2]. The LDH breed, developed through the incorporation of German Blackheaded Mutton and other European meat breeds, is currently recognized for its adaptability, robust constitution, superior meat quality, and high fertility rates (150–160%) [11,18]. German Blackheaded Mutton has been employed to enhance not only Lithuanian Blackface and Latvian Dark-Headed sheep in the Baltic region [19], but also various breeds in other countries, where it has demonstrated notable improvements in performance [20,21,22]. Historical data from Danta (1952–1953) reported that the average weight of LBF females at 7–8 months was 33.45 kg, while males averaged 39.75 kg. After the implementation of a 70-year breeding program, the weights of purebred LBF sheep at the same age increased by 4.72 kg for females and 1.85 kg for males. Although in the present study, the growth of crossbred young sheep was not as intensive as in GBH × Tsigai crossbreeds under intensive fattening (226 g) [23]. Recent introgression of German Blackheaded Mutton into the LBF population further increased the weight of crossbreeds with varying proportions of GBM genetics. Despite the fact that some authors of studies on German sheep breeds have found significant inbreeding depression for daily gain in GBM [24], the findings of the present study indicate that the introgression of GBM into LBF is an effective strategy for enhancing lamb growth rates. In Lithuania, the meat processing industry prefers sheep of at least a 40 kg live weight which are no older than one year of age. Our analysis revealed that crossbreeds reached the desired weight earlier than purebred Lithuanian Blackface (LBF) sheep. Therefore, crossbreeding can be utilized in commercial farming. This improvement aligns with market demands, as the sheep industry increasingly requires faster-growing animals to achieve greater commercial success.
In sheep as in other farm animals, both genetic and non-genetic factors affect reproductive traits. These factors relate to the animal’s genotype, environment, and nutrition and management [25]. The results of the study reported by Gül et al. [26] showed that season has a significant influence on birth weight, weaning weight, and litter size and also indicated that the mentioned factors can be influenced by a pasture (as a food source) feeding regime, mating time, and climate characteristics. However, our study revealed a significant effect of season on lamb weight at three months of age. Our results in this study are consistent with the findings of Polish authors who reported that the size of the litter had the highest impact on lamb rearing results [27]. An annual rhythm of ovarian cyclicity characterized by season-dependent cessation (anestrus) and restoration (breeding season) of ovulatory ovarian cycles is more typical in ewes derived and managed in temperate climates [28]. This can explain normal ovulatory cycles of LBF ewes occurring in autumn and early winter. However, the timing and duration of the breeding season can be affected by interactions between, different factors such as breed, geographical origin, nutritional and lactational status, social interactions, and the season of parturition [28,29]. In Lithuania, sheep mating season traditionally starts after pasture season, and this can lead to more successful LBF ewe parturitions and winter-born lamb growth. Another study [30] also indicated that LBF ewes lambing in winter were 10.4% more fertile than those lambing in spring, and winter lambs were 0.2 kg heavier at birth and 2.8 kg heavier at weaning than spring lambs. In the present study, the higher weight of crossbred lambs born in spring is consistent with a previous analysis [31] which showed that GBM ewes gave birth to heavier lambs in spring. Although in German Blackheaded Mutton sheep selection, more emphasis is placed on phenotypical traits, growth and wool fineness, and the color and uniformity of the fleece, selection for high lambing rate has resulted in ewes with a lambing rate of up to 180% [32]. GBM selection for high lambing rate could influence different seasonal effects on purebred LBF and crossbred (LBF × GBM) sheep. Moreover, seasonality in reproduction is naturally accompanied by variation in the availability and price of meat over the year, affecting the economy [29,33], and the seasonal distribution of lambings in other countries differs from that in our country and LBF sheep breed [34,35].

5. Conclusions

The introgression of German Blackheaded Mutton to Lithuanian Blackface sheep positively affected lamb birth weight and growth. Purebred Lithuanian Blackface ewes demonstrated high prolificacy; however, a litter size increase to three lambs showed a decrease in lamb birth weight. The lambs from larger litters also demonstrated a lower weight during further growth. Most ewes (71.4%) gave birth once per year in winter (December–February). Although the differences in the weight of lambs born in different seasons were insignificant, the lambs born in winter at three months of age were 2.45 kg heavier than the lambs born in spring. Lithuanian Blackface sheep showed the highest adaptability to lambing in winter. Crossbred lambs born in spring and summer demonstrated faster growth than purebred Lithuanian Blackface lambs. The obtained results showed that GBM introgression in LBF sheep may also facilitate the adaptation of LBF sheep reproduction to changes in seasonality. Sex appeared to show an effect only at the age of eight months, when the weight difference between males and females increased to 3.45 kg.
Crossbreeding was used exclusively for the formation of a new line with minimal introgression of another breed, aiming to expand the diversity of genealogical structure through the paternal line and to improve performance. The obtained information can provide new insights for research into the breeding of local breeds and the development of the breeding program of the Lithuanian Blackface sheep breed aimed at optimizing lamb growth without sacrificing breed integrity.

Author Contributions

Conceptualization, R.Š. and V.R.; methodology, V.R. and R.Š.; software, V.R.; validation, R.Š. and V.R.; formal analysis, V.R.; investigation, V.R. and R.Š.; resources, R.Š.; data curation, R.Š.; writing—original draft preparation, R.Š. and V.R.; writing—review and editing, R.Š. and V.R.; visualization, V.R.; supervision, R.Š. and V.R.; project administration, R.Š. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

This study was approved by the Institutional Board of the Animal Science Institute of the Lithuanian University of Health Sciences (protocol No. 24/01/30/01) on 30 January 2024.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Acknowledgments

We are grateful to the UAB Genetiniai ištekliai national sheep farm “Šeduvos Avininkystė” for providing the data.

Conflicts of Interest

The authors declare no conflicts of interest.

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Agriculture 15 00031 g001
Figure 1. Genotype x season interactions at 4 months of age.
Figure 1. Genotype x season interactions at 4 months of age.
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Figure 2. Genotype x sex interactions at 8 months of age.
Figure 2. Genotype x sex interactions at 8 months of age.
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Table 1. Description of newborn lamb distribution in different sizes of litters by their genotype and birth weight.
Table 1. Description of newborn lamb distribution in different sizes of litters by their genotype and birth weight.
GenotypeLitter SizeN%Birth Weight
Mean ± SEMinMax
LBF1286651.624.32 ± 0.024.294.35
2257547.643.90 ± 0.023.863.93
3360.733.58 ± 0.153.293.87
6.25 GBM16280.454.50 ± 0.114.274.72
22319.553.88 ± 0.193.524.25
3-----
12.5 GBM114262.34.28 ± 0.084.144.43
28637.73.82 ± 0.103.634.01
3-----
25 GBM19063.833.95 ± 0.093.764.13
25136.173.65 ± 0.133.413.90
3--
50 GBM13861.294.04 ± 0.153.764.33
22438.713.93 ± 0.183.574.29
3-----
LBF—Lithuanian Blackface sheep; GBM—German Blackheaded Mutton; N—number of animals.
Table 2. Effects of genotype and litter size on weight of newborn lambs and their growth.
Table 2. Effects of genotype and litter size on weight of newborn lambs and their growth.
WeightGenotypeLitter Sizep-Value
LBF
(n = 4925)		6.25%GBM
(n = 85)		12.5% GBM
(n = 227)		25% GBM
(n = 141)		50% GBM
(n = 62)		1
(n = 2866)		2
(n = 2574)		GLS
At birth4.0 ± 0.104.3 c ± 0.164.0 d,a ± 0.093.7 b ± 0.144.00 ± 0.164.2 ± 0.083.8 ± 0.080.155<0.001
2 months16.7 e ± 0.3016.5 e ± 0.9115.1 e ± 0.5611.6 f ± 0.6313.7 ± 2.5015.9 ± 0.4813.9 ± 0.42<0.0010.041
3 months19.4 ± 0.5920.1 ± 0.5920.4 ± 0.4719.0 ± 1.1521.5 ± 1.2520.7 ± 0.4119.0 ± 0.470.6300.141
4 months22.4 c ± 0.6622.5 ± 1.9725.1 a,d ± 0.7422.0 b ± 0.9920.1 b ± 2.2723.5 ± 0.6721.9 ± 0.640.0130.206
8 months37.8 a ± 0.8440.0 ± 3.4239.7 d,a ± 0.8541.7 b ± 1.2541.5 ± 2.3440.3 ± 0.8439.0 ± 0.810.0330.683
12 months41.2 f ± 0.7253.8 e ± 1.5845.8 f ± 0.7144.6 f ± 1.3940.8 f ± 2.9045.7 ± 0.5743.2 b ± 0.80<0.0010.108
LBF—Lithuanian Blackface sheep; GBM—German Blackheaded Mutton sheep; G—genotype; LS—litter size. Mean values with different superscripts of GLM LSD tests for groups differ significantly. a,b p < 0.05; c,d p < 0.01; e,f p < 0.001.
Table 3. Effects of season and sex on weight of newborn lambs and their growth.
Table 3. Effects of season and sex on weight of newborn lambs and their growth.
WeightSeasonSexp-Value
Winter (n = 3892)Spring (n = 1484)Summer (n = 62)Male (n = 2647)Female (n = 2793)SeasonSex
At birth4.0 ± 0.054.1 ± 0.094.1 ± 0.254.1 ± 0.123.9 ± 0.120.9010.521
At 2 months14.6 ± 0.4914.6 ± 0.4817.1 ± 0.9315.1 ± 0.4415.1 ± 0.440.1740.556
At 3 months20.9 e ± 0.2919.1 f ± 0.3818.9 ± 1.5320.2 ± 0.4019.6 ± 0.470.0140.776
At 4 months22.3 ± 0.6122.9 ± 0.7623.2 ± 1.3422.5 ± 0.7323.1 ± 0.560.6870.582
At 8 months40.9 ± 0.6737.7 ± 1.1041.8 ± 2.3441.5 ± 0.8037.9 ± 0.920.182<0.001
At 12 months44.9 ± 0.6744.3 ± 0.6742.4 ± 2.4146.7 ± 0.7442.5 ± 0.660.1350.147
Mean values of GLM LSD tests for the groups with different superscripts differ significantly. e,f p < 0.001.
Table 4. p-Values indicating factor interactions.
Table 4. p-Values indicating factor interactions.
WeightGenotype × Litter SizeGenotype × SexGenotype × SeasonSeason × Litter SizeSeason × Sex
At birth0.6120.9050.7010.4690.731
At 2 months0.8630.1870.3010.8610.970
At 3 months0.4580.9480.1070.0230.710
At 4 months0.1370.4220.0320.7880.703
At 8 months0.2300.0100.1050.5800.008
At 12 months0.4880.1890.0200.2290.611
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Šveistienė, R.; Razmaitė, V. Growth Dynamics of Lithuanian Blackface Lambs: Role of Crossbreeding with German Blackheaded Mutton Rams, Sex and Seasonality. Agriculture 2025, 15, 31. https://doi.org/10.3390/agriculture15010031

AMA Style

Šveistienė R, Razmaitė V. Growth Dynamics of Lithuanian Blackface Lambs: Role of Crossbreeding with German Blackheaded Mutton Rams, Sex and Seasonality. Agriculture. 2025; 15(1):31. https://doi.org/10.3390/agriculture15010031

Chicago/Turabian Style

Šveistienė, Rūta, and Violeta Razmaitė. 2025. "Growth Dynamics of Lithuanian Blackface Lambs: Role of Crossbreeding with German Blackheaded Mutton Rams, Sex and Seasonality" Agriculture 15, no. 1: 31. https://doi.org/10.3390/agriculture15010031

APA Style

Šveistienė, R., & Razmaitė, V. (2025). Growth Dynamics of Lithuanian Blackface Lambs: Role of Crossbreeding with German Blackheaded Mutton Rams, Sex and Seasonality. Agriculture, 15(1), 31. https://doi.org/10.3390/agriculture15010031

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