Cross-bred Sheep Research Articles

Macroscopic and Microscopic Development of the Stomach in Hamdani Crossbred Sheep Fetuses (Ovis aries)

The ruminant stomach is a critical digestive department in terms of converting low-quality feed into high nutrient-value substances. In these animals, there is a compound stomach structure with 4 compartments. Understanding the developmental structure of the stomach at macroscopic and microscopic levels is especially important in terms of nutrition. Türkiye can be considered one of the leading countries in the world in terms of sheep breeding. Our study aimed to investigate macroscopically and microscopically the developmental structures of the stomach of Hamdani crossbred sheep fetuses collected at different gestation periods. For this purpose, a total of 15 fetuses, 5 fetuses each from 3 different periods of pregnancy, were included in the study. The stomachs of the fetuses were dissected simultaneously and their topographic and macroscopic features were determined. After routine histological procedures, the stomachs separated from the body cavities were stained with Hematoxylin & Eosin and Masson Trichrome stains. As a result of the study, macroscopic and microscopic information about fetal development of the stomach was obtained. It was revealed macroscopically and microscopically that the rumen was the largest part of the stomach until the middle of the 2nd period of gestation, and that the abomasum grew rapidly at the end of this period and showed similar characteristics to the adult sheep stomach. The data of the study will contribute to macroscopic, microscopic, and ultrasonographic studies on the stomach in ruminant animals.

Enhancing lamb growth and meat quality: analysis of kazakh fat-tailed and crossbred in central Kazakhstan's sharply continental climate.

The article presents the results of scientific research on the production of lamb in the conditions of the Akmola region. The experiment was conducted on purebred Kazakh short-tailed rough-haired and cross-bred sheep obtained from industrial crossing of Kazakh short-tailed rough-haired queens with sheep- producers of the hampshire breed. Further, the article presents the results of feeding and fattening, as well as the morphological composition of the carcass of sheep of the Kazakh coarse-haired sheep breed of different ages. The object of the study for feeding and fattening were three groups of experimental sheep of the above-mentioned breed, where compound feed was included in the diet of the I experimental group in the form of top dressing, in the II experimental group, grain waste was also used for top dressing, and the control group was kept in the feed without top dressing. Based on the study of the feeding of experimental sheep, it was found that the absolute increase during the feeding period in experimental sheep who received fertilization in the form of compound feed is higher than in their peers, respectively, by 0.2 and 1.49 kg. In terms of morphological and varietal composition, in particular, the number of cuts of grade 1, there was also an advantage of experimental sheep that received fertilization in the form of compound feed compared to their peers, respectively, by 2.3-8.3%. In general, the results of a study on the growth, development and slaughter qualities of experimental sheep, i.e. purebred Kazakh short-tailed rough-haired and crossbred, obtained from crossing with sheep producers of the precocious breed "hampshire" showed that from the moment of birth to 2 and 4 months. For example, crossbred sheep were slightly superior to purebred peers in terms of the studied indicators. In particular, the results of feeding sheep of the Kazakh coarse-haired broad-tailed breed from 4 to 6 months, depending on the top dressing.

Relationship of Body Weights with the Productive Performance of Lambs of the Awassi and Karakul Breeds and Crossbred Sheep

A study was carried out on 60 ewes of the Awassi and Karakul breeds, and cross at age of birth, weaned and 6 months in Barakat Abi Al-Fadl Al-Abbas Station in Karbala Governorate, Iraq from the first of June 2022 until the first of June of the year 2023.with the aim of studying relationship between body weights (BW) of lambs and productive performance (PP) through a set of factors (Genetic group - Sex of lamb - Age of dams - Month of birth - Weight of dams), The statistical analysis system (SAS) was used to analyze the data. The result is displayed as follows: The genetic group, the sex of lambs, the age of the ewe, and the month of birth didn’t affect BW and average weight gain (AWG) of lambs at birth, weaning, and 6 months of age. Only weight of the ewe had a significant effect (P<0.05) on weight of lambs at 6 months of age. The ewes weighing more than 48 kg were superior to the rest of the other weights, with an average weight of 28.35 kg, while the weight of the ewe did not affect the weight of lambs at birth and weaning, also affected weight of the ewe on rate of weight gain at birth, weaning, and 6 months, with the superiority of ewes weighing more than 48 kg over the rest of the weights. Weaning weight was positively correlated with birth weight and highly significant (P<0.01), and the regression coefficient between 6-month-old body weight and weaning weight was high and significant (P<0.01).

Nano-chromium picolinate and heat stress enhance insulin sensitivity in cross-bred sheep.

This study evaluated the effects of heat stress (HS) and dietary nano chromium picolinate (nCrPic) on metabolic responses of sheep to an intravenous glucose tolerance test (IVGTT), an intravenous insulin tolerance test (ITT) and an intramuscular adrenocorticotropin hormone (ACTH) challenge in sheep. Thirty-six sheep housed in metabolic cages were randomly allocated within 3 dietary groups (0, 400 and 800μg/kg supplemental nCrPic) to either thermoneutral (22°C) or cyclic HS (22 to 40°C) conditions for 3wk. Basal plasma glucose tended to be increased during HS (P=0.052) and decreased by dietary nCrPic (P=0.013) while plasma non-esterified fatty acid concentrations were decreased (P=0.010) by HS. Dietary nCrPic reduced the plasma glucose area under the curve (P=0.012) while there were no significant effects of HS on plasma glucose area under the curve in response to the IVGTT. The plasma insulin response over the first 60min after the IVGTT was decreased by HS (P=0.013) and dietary nCrPic (P=0.022) with the effects being additive. In response to the ITT plasma glucose reached a nadir sooner (P=0.005) in sheep exposed to HS, although there was no effect on the depth of the nadir. Dietary nCrPic decreased (P=0.007) the plasma glucose nadir after ITT. Over the duration of the ITT plasma insulin concentrations were lower in sheep exposed to HS (P=0.013) whereas there was no significant effect of supplemental nCrPic. There was no effect of either HS or nCrPic on cortisol response to ACTH. Dietary nCrPic supplementation decreased (P=0.013) mitogen-activated protein kinase-8 (JNK) and increased (P=0.050) carnitine palmitoyltransferase 1B (CPT1B) mRNA expression in skeletal muscle. Results of this experiment demonstrated that animals under HS and supplemented with nCrPic had greater insulin sensitivity.

Evaluation of the Crossbreeding Scheme and Farmers’ Perception of Awassi and Dorper Crossbred Sheep

The objectives of this study were to characterize the performance of crossbred sheep and crossbreeding scheme and to solicit farmers’ opinions about crossbred sheep. A total of 238 respondents were selected from five districts and data were collected through a personal interview, focus group discussion, measurement of animals, and field observation. Continuous type of data were analyzed using different procedures of SAS, while the estimated breeding value (EBV) for distributed rams was estimated by the WOMBAT software fitting animal model. The findings showed that sheep were the most significant species and that they were primarily raised for meat consumption and income generation. The proportions of crossbred sheep were 79.6% in Angot, 61.3% in Dessie zuria, 64.2% in Gazo, 80.6% in Legambo, and 27.5% in the Kobo area. The sheep crossbreeding program was constrained by feed shortage, lack of improved genotype, and diseases. The ongoing sheep crossbreeding program lacks a proper recording scheme, rams were not selected based on genetic merit, not exchanged in time, lack periodic importation of genetically unrelated rams, and lacks fixing the maximum exotic gene level suitable for the production system. The EBVs of Dorper crossbred rams for birth weight and weaning weight were 0.007 kg and 0.273 kg, respectively. Tikur sheep had an earlier age at first lambing (AFL) than Awassi x Tikur sheep. Likewise, the indigenous Wollo sheep had earlier AFL, short lambing interval, and produced a large number of lambs per lifetime than their Awassi crossbreds. Dorper crossbreds were preferred (9.30 - 72.2 times greater and P &lt; 0.001 ) for their growth rate, physical appearance, preference in the market or price, and milk production of ewes compared with indigenous Tumele sheep. The Awassi crossbred sheep were preferred (odds ratio = 12.7– 90.0 and P &lt; 0.001 ) due to their good physical appearance, fast growth rate, wool yield, milk yield, and better preference in the market compared with Tikur and Wollo sheep breeds. The implementation of the crossbreeding program needs some sort of revision, monitoring, and periodic evaluation. Besides, it must be accompanied by improved management to exploit the expected benefits from the crossbreeding program in the low-input production system.

Hematological blood parameters of pure blood and cross-bred sheep of the Edilbaevsky breed

The article presents the results of a biochemical and morphological analysis of the pure blood and cross-bred sheep of the Edilbaevsky breed, born in different seasons of the year. The blood parameters of the animals of the studied groups studied by us were within the physiological norm, but there were some differences between the groups. It was found that the redox processes in the body of sheep of the cross-breed group were more intense than in peers of the same group, which in turn affected higher indicators of their productivity.

Morphometric traits with reproduction and production performances of indigenous and exotic sheep breeds of Bangladesh

The purpose of this study was to review the existing literature on some important morphological traits associated with reproductive and productive performance in Bangladeshi indigenous and exotic cross sheep. Sheep as small ruminants are essential parts of the crop-livestock of the mixed agricultural farming system playing a crucial role in the livelihood of smallholders in Bangladesh. They are considered risk averters for farmers in a family crisis and seasonal needs through quick sale by direct cash income. Furthermore, their physical products have socio-economic, cultural, and nutritional values: meat, milk, skin, manure, etc. In the past, a number of researchers investigated the relationship between morphometric features and reproductive and productive performance of the referred sheep. Any compilation report is yet not available. Therefore, an update database on Bangladeshi indigenous and exotic cross-breed sheep is required to identify for management and production strategy program. This paper reviewed, discussed, summarized, and compared all articles on morphometric traits and the reproductive and productive performances of sheep in Bangladesh.

ЛИНЕЙНЫЙ РОСТ МОЛОДНЯКА ОВЕЦ ВОЛГОГРАДСКОЙ ТОНКОРУННОЙ МЯСО-ШЕРСТНОЙ ПОРОДЫ И ЕЕ ПОМЕСЕЙ F3 ПО СЕВЕРОКАВКАЗСКОЙ МЯСО-ШЕРСТНОЙ ПОРОДЕ

The article presents the results on the linear growth of sheep of the Volgograd fine-fleeced meat-wool breed and its crossbreeds F3 1/8 bloodline for the North Caucasian meat-wool breed. It was found that cross-bred sheep had better development of individual body articles and a more pronounced meat type of physique.

Diameter and strength of Ethiopian pure and cross-breed sheep wool fibers

The wool fibers fineness and strength have a remarkable role to determine the quality of yarn and the subsequent fabrics. The fineness property of the wool fibers is a crucially important fiber property for grading, classifying, selecting for particular applications such as for suit, blanket, shirt, carpet, and so on. The fineness and strength properties of four indigenous (Menz, Wollo, Farta, Tikur), three exotic (Awasi, Dorper, Corrediale), and four cross-breed (50% Dorper, 50% Awasi, 75% Awsi, Washera/Awasi) sheep wool fibers from the four main body parts (sides, neck, back, and belly) at six teeth removed age of 11 different sheep breeds have been investigated. The samples of wool fibers have been conditioned for 24 h at 20ºC ± 1ºC temperature and 65% ± 2% relative humidity. The specimen for sampling has been determined based on ASTM D2130-01. The results revealed that the fineness and strength of whole fibers taken from different parts of sample sheep varied significantly within the breed and among the breeds. The result revealed that the strength and fineness of the wool fibers have a positive correlation and Ethiopian sheep wool fiber is suitable for numerous types of classical and technical applications.

Dietary nano chromium picolinate can ameliorate some of the impacts of heat stress in cross-bred sheep

Two studies were conducted to evaluate the effect of nano chromium picolinate (nCrPic) during heat stress (HS) in sheep. In the initial study, 36 Merino × Poll cross-bred sheep were individually penned and allocated to 3 dietary treatments (0, 400 and 800 μg/kg nCrPic) for 8 wk. Body composition was determined at the beginning and end of the experiment using dual energy X-ray absorptiometry. The sheep remained in their dietary groups but were then placed in metabolic cages and randomly allocated within the dietary group to differing ambient temperature regimes, i.e., thermo-neutral (TN) (n = 18) and HS (n = 18), for 3 wk. Dietary nCrPic had no effect on growth performance and body composition during the initial study conducted under TN conditions. Heat stress decreased average daily feed intake (ADFI) (P = 0.002) whereas sheep under HS had reduced average daily gain (ADG) and indeed lost weight (P < 0.001). Dietary nCrPic increased both ADFI (P = 0.041) and ADG (P = 0.049) under both TH and HS conditions such that the performance of sheep receiving supplemental nCrPic and exposed to HS was similar to that of control sheep maintained under TN conditions. Heat stress increased rectal temperature (P < 0.001) and respiration rate (P < 0.001), particularly during the hottest parts of the day as indicated by interactions (P < 0.001) between time of day and thermal treatment. Rectal temperature was lower in sheep fed nCrPic (P = 0.050), particularly under peak HS conditions during the afternoon as indicated by the interactions between dietary nCrPic and time of day (P < 0.001) and dietary nCrPic, thermal treatment and time of day (P = 0.010). Similarly, respiration rate was lower in sheep fed nCrPic under peak HS conditions during the afternoon as indicated by the interactions between dietary nCrPic and thermal treatment (P < 0.001) and dietary nCrPic and time of day (P = 0.030). In conclusion, dietary nCrPic can partially ameliorate the negative effects of HS as indicated by the maintenance of ADFI and decreased physiological responses, such as elevations in rectal temperature and respiration rate.

Augmentation of neural activity in peripheral nerve of sheep using 6 kHz subthreshold currents

Objective: To determine how increased excitability from subthreshold currents would alter neural activity as it propagates through the subthreshold currents. Approach: Experiments were performed on two Romney cross-breed sheep in vivo, by applying subthreshold currents either at the stimulus site or between the stimulus and recording sites. Neural recordings were obtained from nerve cuff implanted on the peroneal or sciatic nerve branches, while stimulus was applied to either the peroneal nerve or pins placed through the lower hindshank. Main results: Showed that subthreshold currents applied to the same site as stimulus increased excitation of underlying nerve fibres (p < 0.005). With stimulus and subthreshold currents applied to different sites on the peroneal nerve, the primary compound action potential (CAP) in the sciatic displayed a temporal shift of −2.5 to −3 µs which agreed with changes observed in the CAP waveform (p > 0.05). Significance: These findings contribute to the understanding of mechanisms in myelinated fibres of subthreshold current neuromodulation therapies.

The intrinsic fallacy of market mechanism and private property rights in alleviating the tragedy of the commons

ABSTRACT Economists’ solution to the tragedy of the commons relies on well-defined property rights and competitive market mechanism for limiting individuals’ self-serving, short-sighted actions that result in a dramatic depletion of the common resources. However, this solution implicates a serious threat in terms of sustainability. Recently, deterioration of genetic diversity reached alarming levels, mainly attributed to escalating economic pressure that obliges farmers to shift from local breeds towards more profitable and more productive industrial breeds. This study empirically examines the efficiency of the free market mechanism as a solution to the tragedy of the commons through a unique natural experiment in which a huge demand shock arises regarding sheep. Results robustly show that the free market mechanism can cope with even a very challenging demand shock through the adjustment of prices without any shortage of the commodity. However, this finding does not guarantee that such an outcome is sustainable over the very long term. Analysis of the growth rate of the local sheep breeds population and cross-breed sheep population shows that the trend is overwhelmingly in favour of cross-breeds, thus supporting concerns for a free market mechanism, intrinsically driving the extinction of local sheep breeds, an invaluable genetic resource.

COMPREHENSIVE ASSESSMENT OF FARMING RAMS BREEDING VALUE RELATED TO DIFFERENT GENOTYPES

The results of evaluating the breeding value of rams of different genotypes by a wide range of productivity indicators of their descendants are presented. Tribal rams of the Kharkov interbreed type of Prekos breed of 2-3 years of age, as well as crosses from the introductory crossing of Prekos sheep with the Romanov breed and Merinolandsheep, were evaluated. The resulting offspring were grown under the conditions of one production flock. The evaluation considered the indicators of the reproductive ability of ewes, sex and type of birth of the offspring, the safety of lambs from birth to 20 days of age, the dynamics of the average daily growth of daughters in the uterus and at the age of birth to 20 days and from 21 to 90 days, live weight indicators were considered, cutting and length of hair of daughters at the age of 14 months. Studies have established that the average yield of lambs throughout the sample was 115.3 % per 100 ewes, with significant differences between the estimated producers - from 105.1 to 131.3 %. This indicator did not have a definite relationship with the genotype of the estimated sheep. Among the offspring of all rams, males slightly prevail over females in the ratio of 1.09 to 1. This advantage is due to the large number of rams born among same-sex twins. Their part exceeded 28 %, while only 23.4 % turned out to be similar in type of birth. By the sum of the ranks that were put to individual sheep for the indicators of the average daily growth of daughters at different periods of their growth, the best cross-breed sheep No. 1625 and No. 9953 are distinguished. On the whole, there is a fairly clear tendency for a positive relationship between the ranks for the growth rate in the embryonic period and the same indicator for posterity aged 21-90 days. According to both the ranking and the probity-based evaluation results, ram No. 1625 (a created line based on crossing with the Romanov breed) is assigned to complex improvers. The rest topping ram out to be improvers of individual traits, and the producer of the breed Prekos No. 1823 was an improvement in production of wool and length of staple. Ram No. 1960 turned out to be a complex deteriorator in the quality of offspring. The descendants of rams No. 4464 and 9953, derived from the breed of Merino landscape, reliably (p≤0.01), by 18.6-20.8 % in terms of wool coefficients, are inferior to the daughters of ram No. 1823, breed Prekos, which is an unconditional evidence of the strengthening of their characters meat productivity over wool one.

Variation in KRTAP6-1 affects wool fibre diameter in New Zealand Romney ewes.

Variation in KRTAP6-1 has been reported to affect wool fibre traits in Merino cross-breed sheep and Chinese Tan sheep, but little is known about whether these effects persist in other breeds. In this study, variation in KRTAP6-1 was investigated in 290 New Zealand (NZ) Romney ewes sired by 16 different rams. Polymerase chain reaction single-stranded conformational polymorphism (PCR-SSCP) analysis revealed four variants (, , and of KRTAP6-1, and nine genotypes (AA, AB, AE, AF, BB, BE, BF, EE and FF) in these ewes. Among the 243 ewes that had genotypes with a frequency of over 5 % (i.e. AA, AB and BB), the presence of was found to be associated with reduced mean fibre diameter (MFD) and increased coefficient of variation in fibre diameter (CVFD), whereas the presence of had a trend of association with decreased coarse edge measurement (CEM). A genotype effect was also detected for MFD and CVFD. No associations were detected for fibre diameter standard deviation (FDSD), mean fibre curvature (MFC) and medulation. These results suggest that variation in KRTAP6-1 affects wool fibre diameter in NZ Romney ewes, confirming the finding in Merino cross-breed sheep.

Characterizing the Wool Fiber Fineness and Crimps of Menz, Dorper and Their Crossbreed Sheep

Ethiopia possesses about 30 million of sheep population which could be taken as a source of raw material for textile industries as a wise strategy to manage their natural fibers scarcity. This work explored the possible wool fiber potentials on selected sheep breeds. Three representative breeds as indigenous (Menz), exotic (Dorper) and crossbreed (50% Dorper/50% Menz) sheep breeds were considered to characterize the wool fiber properties. Samples have been taken from four main body parts for four age categories of each sheep breeds. All samples were allowed to standard laboratory conditioning before testing, and then, properties are measured based on ASTM. The results revealed that the fibers diameter and crimp frequencies of wool fiber of the three sheep breeds in Ethiopia are significantly different from each other. The crossbreeding of the Menz sheep with Dorper provides fine wool fiber. The wool fiber properties particularly the fineness and crimps of Menz, Dorper and 50% Dorper sheep of different parts and age categories are significantly different. Hence, these wool fibers shall be classified and graded based on their breeds to use for different applications, and also it could help to explore more on wool fiber production.

Diet selection and preference of small ruminants during drought conditions in a dryland pastoral system in South Africa

Semi-arid to arid areas are prone to droughts which are frequent occurrences in South Africa’s rangelands. Drought can trigger plant species compositional changes in rangelands thus influencing the availability and quality of forage for livestock. The availability and quality of forage drives livestock production, especially among pastoralists who mainly rely on the natural rangeland to sustain their livestock and livelihoods. The aim of this study was to determine the forage selection of cross-bred sheep, Swakara sheep (Ovis aries) and Boer goats (Capra hircus), during the wet season in the summer rainfall Nama Karoo and winter rainfall Succulent Karoo biomes in Namaqualand, South Africa. Since this dryland pastoral system was experiencing drought conditions during the study period of 2016 & 2017, the focus of the study was placed within this context to determine, (1) the availability of forage for small ruminants, (2) the nature of diet selection of different small ruminant groups and how it vary between the two biomes, and (3) the role livestock species, breeds and season play in forage preferences. We established diet selection, preference and dietary overlap by using direct observation of livestock grazing in the veld. Results indicate that availability of forage influence diet selection and preferences of all small ruminant groups. There was a high dietary overlap between mixed bred and Swakara sheep irrespective of the biomes. During 2016 annual herbs made up a large proportion of the sheep’s diets indicating an overdependence to this forage resource when it became available in the rangeland. However, due to the drought spell extending into 2017, annual herbs became less available and therefore altered the forage choices of both sheep groups. Goats were primarily browsers in the Succulent Karoo biome where shrubs dominate, but were considered grazers in the Nama Karoo biome where grasses were dominant. Moreover, all small ruminant groups in this study showed non-selective grazing tendencies which is an important grazing management tool to ensure that rangeland resources are not over exploited. We conclude by arguing that the mixture of different livestock species by pastoralists is an effective diversification strategy for better use of rangelands with herbaceous and woody plants during drought periods.

Hematological indicators and biochemical status of the blood of purebred and crossbred rams born in different seasons of the year

The article presents the results of biochemical and morphological analysis of the blood of purebred and crossbred sheep born in different seasons of the year. The main indicators of blood of animals in all experimental groups were within physiological norm, however some differences between groups were noted. It is established that cross-bred sheep of winter lambing possess more active metabolism, high energy of growth and, greater meat productivity in comparison with purebred animals. &nbsp; &nbsp

Sheep breed and shearing influences attraction and blood-feeding behaviour of Culicoides (Diptera: Ceratopogonidae) on a UK farm

BackgroundCulicoides biting midges (Diptera: Ceratopogonidae) are responsible for the biological transmission of arboviruses of international importance between ruminant livestock. These arboviruses include bluetongue virus (BTV) and Schmallenberg virus (SBV), which have emerged in unprecedented outbreaks in northern Europe. The impact of breed and shearing of sheep on Culicoides: host contact rates has not been investigated in detail and has the potential to influence arbovirus transmission and control measures employed to limit spread.MethodsAttraction of Culicoides to Hartline and Hartline/Suffolk cross-breed sheep was compared using 224 drop trap collections over 22 nights and 181 catches from sheared or unsheared Hartline/Suffolk ewes were made over 17 nights to compare Culicoides activity and rates of blood engorgement.ResultsA total of 31,314 Culicoides was collected in the two trials and females of the subgenus Avaritia represented over 96.9% of individuals collected. Attraction to breed was dependent upon species of Culicoides and physiological status, with a significantly greater number of individuals collected on the cross-breed sheep. Shearing of sheep did not significantly increase or decrease the number of Culicoides attracted but increased the rate of successful engorgement.ConclusionsBoth breed and shearing were shown to influence Culicoides biting rate on sheep. These data are useful in a direct context in understanding the likely impact of control measures against arboviruses including BTV and SBV and additionally in providing data from field-based studies to enable modelling exercises of arbovirus transmission and spread.

Differences in tick infestation of Tunisian sheep breeds.

Different infestation patterns by ixodid ticks were studied in three sheep breeds in Tunisia: Barbarine, Queue Fine de l'Ouest and their cross-bred animals. During one year, 700 sheep were monitored and examined for tick infestation. A total of 722 ticks were collected from sheep ears. The most frequent tick species was by far Rhipicephalus sanguineus sensu lato (99%) and there were few specimens of Rhipicephalus bursa (1%) (p < 0.001). Overall infestation prevalence was estimated at 10.4%. The lowest infestation prevalence was in Barbarine sheep (7.3%), followed by Queue Fine de l'Ouest (16.7%) and the highest prevalence was in cross-bred sheep (19.1%) (p < 0.001). Mean overall infestation intensity was 1.6 ticks/sheep: lowest in Barbarine (1.4), followed by Queue Fine de l'Ouest (1.7) and cross-bred sheep (1.8). Similarly, abundance was lowest in Barbarine sheep (0.1), and was 0.3 in Queue Fine de l'Ouest and cross-bred animals. The results demonstrated a reduced infestation, possibly due to reduced attractiveness and/or increased resistance to tick infestation, of the Barbarine breed compared with the other two breeds. Further behavioural, genetic and molecular studies are needed to explain the mechanisms for the lower infestation indicators.

Electrocardiographic Studies in Different Age Groups of Nellore Cross-Breed Sheep

Electrocardiographic Studies in Different Age Groups of Nellore Cross-Breed Sheep