Pedigree analysis is an important tool for assessing genetic variability and detecting heritage patterns in domestic animals. This study aimed to (1) assess genetic variability, (2) estimate genetic ...parameters for daily milk yield (DMY), fat content (FC), and protein content (PC), and (3) estimate the impact of inbreeding on the aforementioned dairy traits in Istrian sheep breed. The generation interval was 3.8 years. The average family size per sire and dam was 13.5 and 1.6, respectively. There were 923 female and 282 male founders (f), 105 male and 137 female effective founders (f
e
), and 72 male and 95 female effective ancestors (f
a
). A total of 28 sires and 34 dams explained 50% of the genetic variability. The effective number of male and female founder genomes (f
ne
) was 33 and 53, respectively. Low f
e
/f (0.37 and 0.15), high f
e
/f
a
(1.45 and 1.44), and low f
ne
/f
e
(0.45 and 0.39) for males and females indicated overuse of a small number of animals in reproduction and substantial loss of founder alleles. The heritabilities of MY, FC, and PC were 0.09, 0.03, and 0.06, respectively. Genetic correlations between DMY and FC, DMY and PC, and FC and PC were −0.22, −0.27, and 0.70, respectively. Regression of phenotypes on inbreeding coefficient (
) within the animal genetic model revealed negligible inbreeding depression for all traits (p<.01; a 1% increase in
decreased DMY, FC, and PC by 0.002 kg/day, 0.01%, and 0.002%, respectively). Regression of breeding values on
was insignificant for all traits (p>.05).
HIGHLIGHTS
Genetic diversity, genetic parameters and the impact of inbreeding on dairy traits were estimated using pedigree information.
Results indicate recent loss of genetic variability, low heritability and negligible impact of inbreeding on dairy traits.
Genomic optimum contribution selection is the best solution to achieve genetic gain and slow down the loss of genetic variability in this population.
The Istrian sheep breed has been subjected to selection for dairy traits for more than two decades. However, a detailed study of some important population-specific parameters such as effective ...population size (Ne) and connectedness between flocks has never been carried out. The aim of the study was to examine the above parameters in dairy Istrian sheep subjected to a national selection program. The Ne was estimated as the mean rate of increase in coancestry, and connectedness was determined using four different statistics. The Ne was estimated at 73 animals with pedigree constraints imposed on 4 equivalent generations and 3 full generations. Analysis of ΔNe (“sliding window approach”) revealed a negative ΔNe indicating a progressive loss of genetic variability (ΔNeNEG≥4 = −6.6, p < 0.01; ΔNeNFG≥3 = −4.9, p > 0.05). The overall connectedness (r¯ ~ 0.0001) was below the acceptable level for unbiased ranking of the animals belonging to different flocks (ri,j = 0.05). OCS appears to be the best option for the long-term survival (self-sufficiency) of the breed, but genetic links between flocks need to be strengthened to allow unbiased ranking of the animals based on the estimated breeding values.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Around 10.5 million tonnes of sheep milk are produced worldwide, and around 3.1 million tonnes in Europe. In Europe, sheep milk production has stagnated slightly in recent years and currently ...accounts for around 1/3 of the global production. Due to its high content of dry matter, milk fat, total protein and casein, sheep milk is an excellent raw material for cheese production. Milk processing and cheese making are not only economically important, but also part of the cultural heritage based on a long tradition, often taking place in rural and less developed areas. Milk production and quality are very complex and are influenced by numerous factors, the most important of which are breed, feeding and body condition, parity and stage of lactation, milking and udder health, and environmental factors. In addition, different types of stress such as heat stress, nutritional stress, weaning stress, shearing stress, stress of regrouping, etc. have a significant impact on the welfare and health of the sheep as well as on the quantity of milk produced, its chemical composition, processing characteristics and the economic efficiency of the flock. In recent years, due to climate change, there has been an increasing number of studies on the effects of heat stress on the reproductive and production characteristics of sheep, as well as on their welfare and health. In addition, heat stress is often associated to the feed and the lack of water. The effects of stress are particularly pronounced in extensive sheep farming and milk production, which are prevalent in sheep farming. The aim of this paper is to describe the effects of the main types of stress on the quantity and chemical composition of sheep milk and on animal welfare.
Over the past three decades, the scientific and public interest has been initiated by studies in which the negative effect of milk consumption of beta-casein A1 variant has been observed on ...consumers’ health. The production of "A2 milk" is one of the ways to economically increase the competitiveness of small and medium-sized dairy farms. Breeders of endangered local breeds are also interested in reaffirmation through production of “A2 milk”. The aim of this study is to determine frequencies of A1 and A2 variants of beta-casein in three commercial and three local breeds of cattle in Croatia, and their relationship with production indicators of commercial breeds in the first three lactations. The genomic DNA was extracted from hair by using a commercial kit, used for determination of CSN2 genotypes by means of PCRRFLP method. Data for milk yield and chemical composition were provided by the central database. The dominant presence of A2 variant beta-casein in the investigated cattle breeds (0.650-0.758) and the increase in the frequency of A2 beta-casein in the population of Simmental and Istrian cattle were determined. The association of A2A2 and A1A1 genotypes of beta-casein with lactation production and milk fat content in the first and second lactation was observed (p <0.05). The dominance of the A2 allelic variation of beta-casein makes the researched conventional and local breeds suitable for the production of "A2 milk. The breeding extension of A2 allelic variation of beta-casein within local breeds of cattle should be carried out carefully not to lose part of the existing genetic variability.
The Croatian Posavina horse (CPH) is native Croatian breed under a conservation program and under various programs of economic use (ecosystem services, agrotourism, and meat production). The aim of ...this study was to analyze the status of the CPH population through an analysis of their pedigree (28,483 records), phenotype (292 licensed stallions, 255 mares), and genetic structure (292 licensed stallions). The average generation interval was 8.20 years, and the number of complete generations was 1.66. The effective number of founders and ancestors was 138 and 107, respectively, with a ratio of 1.29, and the genetic conservation index was 4.46. As for the morphometric characteristics, the average withers height of the stallions was 142.79 cm, the chest circumference was 194.28 cm, and the cannon bone circumference was 22.34. In mares, the withers height, chest, and cannon bone circumference were lower (139.71 cm, 190.30 cm, and 20.94 cm, respectively). Genetic microsatellite analysis of the 29 sire-lines showed high genetic diversity, expressed as the mean allele number (7.7), allele richness (4.0), and expected heterozygosity (0.740). There was no evidence of high inbreeding or a genetic bottleneck. The genetic and phenotypic data indicate that the CPH is an important and diverse reservoir of genetic diversity and can be conserved because of its special characteristics (adaptability).
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This study aimed to examine the impact of ewe’s age at first lambing (AFL) on days in milk (DIM), average daily milk yield (DMY), and total milk yield (TMY). Symmetrical bimodal distribution of AFL ...enabled classification of maidens in those mated in the first (47%) or second year of life (53%). After accounting for all available sources of phenotypic variability with the linear mixed model for repeated records, it was estimated that AFL had a statistically significant effect only on DIM (p < 0.001). The litter size had a significant effect only on TMY (p < 0.001), while the effect of the parity was significant for all the examined traits (p < 0.001). The results of the study suggest that prolongation of age at first mating to the second year of life is not justified in dairy-orientated sheep farms. However, more evidence on this issue is needed for generalization, especially considering some other traits that can impact profitability of dual-purpose sheep farms (reproduction traits, growth rate of lambs, etc.).
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The two native Croatian donkey breeds (Littoral-Dinaric donkey and Istrian donkey) were marginalized in the second half of the 20th century and were on the verge of biological extinction. The aim of ...this study was to analyze the demographic and genetic status of two donkey breeds, two decades after the start of protection by analyzing their pedigrees and genetic structure. The average generation interval was higher for the Istrian donkey (7.73) than for the Littoral-Dinaric donkey (7.27). The rate of the effective number of founders compared with the effective number of ancestors in the Littoral-Dinaric donkey (1.03; 325/316) and in the Istrian donkey (1.08; 70/65) revealed no evidence of a genetic bottleneck. The inbreeding coefficient (F) and the average relatedness coefficient (AR) was lower in the Littoral-Dinaric donkey population (0.99%; 0.13%) than in the Istrian donkey population (1.77%; 1.10%). Genetic microsatellite analysis showed relatively high genetic diversity in Littoral-Dinaric donkey and Istrian donkey breeds, expressed by mean allele number (5.92; 5.85) and expected heterozygosity (0.650; 0.653). Genetic differentiation between the Littoral-Dinaric donkey and the Istrian donkey has not significantly increased in the last two decades (FST = 0.028). Genetic analysis also showed no evidence of high inbreeding or genetic bottleneck in both breeds. A total of 11 haplotypes including 28 polymorphic sites were found in 30 samples. Analysis of mtDNA has shown that the Littoral-Dinaric donkey and Istrian donkey breeds belong to the Equus asinus africanus group. The study confirms the need to use different analytical approaches to get a regular and complete insight into the situation and trends within and between breeds, so that the existing diversity can be fully preserved.
Istrian goat is an autochthonous Croatian breed which inhabited Istrian peninsula and was important in milk production and human nutrition, especially for poor people. For centuries Istrian goat was ...a recognizable heraldic symbol of Istria, but in her real form almost disappeared from the breeding area. The revitalization and reaffirmation of Istrian goat began with several dozen remaining breeding animals, after a decade-long breeding ban. Genetic characterization of the Istrian goat population is necessary for providing insight into the state of genetically preserved structure within population as well as positioning Istrian goats within phylogenetically related breeds. Microsatellite and mtDNA analysis of reproductive individuals of Istrian goat and related breeds, Croatian White goat and Saanen goat was carried out. In the population of Istrian goat, higher allelic variability (nA = 9.7; AR = 7.4) were found as well as significant genetic distance (FST = 0.068 - 0.086) in relation to other two breeds. Such results indicated that Istrian goat constitutes a separate genetic identity. The observed ten haplotype sequences of the D-loop mtDNA also confirm the significant genetic richness of the maternal hereditary component. The observed haplotypes in the population of Istrian goat belong to lineage A. A smaller number of haplotypes shows similarity to the group of “white” goats, indicating traces of earlier limited but targeted crossing of Istrian goats. The genetic profile analysis of Istrian goats indicates a high level of genetic variability and provides guidelines for a long-term conservation program. The preserved genetic and promising potential of milk production of Istrian goat makes a significant basis for her economic reaffirmation. Orientation of the breed towards milk production could be an efficient strategy for its effective preservation.
The aim of this study was to investigate characteristics of calves rearing technologies at family farms in northern Croatia (Varazdin and Medjumurje County). Calves up to eight weeks of age at family ...farms in Varazdin County were kept mostly tied (57.7%). After eight weeks of age, calves in both analysed Counties are dominantly kept tied. First colostrums ration was given to calves within first three hours after calving, i.e. on 99.2% of analysed farms in Varazdin County and 90% of analysed farms in Medjimurje County. On the majority of farms colostrums is given to the calves in amount of 1-1.5 litres (51.9% Varazdin, i.e. 65% Medjimurje County). Freezing of colostrum is done at 10.5% of analysed farms in Varazdin and 15% of analysed farms in Medjimurje County. In Varazdin County farmers feed calves with milk or milk replacer significantly longer (P<0.001) than farmers in Medjimurje County. Consequently, calves in Medjimurje County consumes significantly lower quantities of milk or milk replacer (P<0.001). Calves in the Medjimurje County are significantly earlier fed with solid feed: hay (P<0.05), pre-starter or starter (P<0.001), and water (P<0.001) than on farms at the Varazdin County. Total mixed ratio (TMR) was used neither in Varazdin nor in Medjmurje County in calves’ nutrition, and colostrums quality was checked only at 3% of farms in Varazdin County (4 farms), and only at one farm in Medjimurje County.
Milk production is one of the possible economic uses of donkey population. The Littoral- Dinaric donkey is numerous, but the structural changes in rural areas during the last decade have pushed it ...into a group of endangered genetic heritage. The aim of this research is to determine the production potential, lactation characteristics, chemical composition and hygienic quality of the Littoral-Dinaric ass milk. The average milk production was 172.12 mL per milking with the average fat percentage of 0.33 %, milk protein 1.55 %, and lactose 6.28 %. The low average number of somatic cells and bacterial count are noticed in ass’s milk (4.09 mL log-1; 3.58 mL log-1). A significant influence of lactation stage on the milk quantity and proportion of dry matter (P<0.01), as well on the proportion of milk fat and milk protein (P<0.05), was observed. Also the influence of the season on productivity, and the proportion of dry matter and milk fat (P<0001), as well as milk protein (P<0.01) was also significant. Productivity of the Littoral-Dinaric ass in the pasture system is relatively modest, but the direct and indirect benefits from this kind of production are multiple. That is the reason to continue the development of donkey milk production technology.
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