Italian Holstein Friesian Research Articles

Milking system and diet forage type effect on milk quality of Italian Holstein-Friesian

Moving from conventional (CMS) to automatic (AMS) milking systems could affect milk quality. Moreover, the type and preservation methods of the forages used in the TMR, such as alfalfa hay (HTMR) or corn silage (STMR) have been demonstrated to modify milk composition. Thus, this study investigated the effect of implementing AMS and different diet forage types on the quality of Italian Holstein-Friesian bulk milk. Milk samples (n = 168) were collected monthly from 21 commercial farms in northern Italy during a period of 8 mo. Farms were categorized into 4 groups according to their milking system (CMS vs. AMS) and diet forage type (HTMR vs. STMR). Milk quality data were analyzed through the mixed procedure for repeated measurement of SAS with the milking system, diet forage type, and sampling day as fixed effects. Milking through the AMS led to lower milk fat, freezing point, and β-LG A; longer coagulation time; and higher K content, pH, and β-LG B than CMS. Cows fed STMR produced milk with greater fat, protein, casein, Mg content, titratable acidity, and β-LG A, but with reduced curd firming time, freezing point, and β-LG B than those fed HTMR. In conclusion, milk quality is not only altered by the diet's forage type and characteristics but also by the milking system.

The role of inbreeding depression on productive performance in the Italian Holstein breed.

Inbreeding depression has become an urgent issue in cosmopolitan breeds where the massive genetic progress achieved in the latest generations is counterbalanced by a dramatic loss of genetic diversity causing increased health issues. Thus, the aim of this study was to estimate inbreeding depression on productive traits in Holstein dairy cattle. More precisely, we aimed to i) determine the level of inbreeding in 27,735 Italian Holstein dairy cows using pedigree and genotype data, ii) quantify the effect of inbreeding on 305-d in milk yield (MY; kg), fat yield (FY; kg), and protein yield (PY; kg) based on different statistical approaches, iii) determine if recent inbreeding has a more harmful impact than ancestral ones, and iv) quantify chromosomal homozygosity effect on productive traits. Quality control was performed on the autosomal chromosomes resulting in a final dataset of 84,443 single nucleotide polymorphisms. Four statistical models were used to evaluate the presence of inbreeding depression, which included linear regression analysis and division of FPED and FROH into percentile classes. Moreover, FROH was partitioned into i) length classes to assess the role of recent and ancestral inbreeding and ii) chromosome-specific contributions (FROH-CHR). Results evidenced that inbreeding negatively impacted the productive performance of Italian Holstein Friesian cows. However, differences between the estimated FPED and FROH coefficients resulted in different estimates of inbreeding depression. For instance, a 1% increase in FPED and FROH was associated with a decrease in MY of about 44 and 61 kg (P < 0.01). Further, when considering the extreme inbreeding percentile classes moving from the 5th lowest to the 95th highest, there was a reduction of -263 kg and -561 kg per lactation for FPED and FROH. Increased inbreeding, estimated by FPED and FROH, had also a negative effect on PY and FY, either fit as a regressor or percentile classes. When evaluating the impact of inbreeding based on runs of homozygosity (ROH) length classes, longer ROH (over 8 Mb) had a negative effect in all traits, indicating that recent inbreeding might be more harmful than the ancestral one. Finally, results within chromosome homozygosity highlighted specific chromosomes with a more deleterious effect on productive traits.

Factors affecting true and functional productive lifespan in Italian Holstein-Friesian cows

The identification of factors affecting longevity in dairy cows is of great importance to improve their length of productive life. Cows can be replaced for poor milk production (i.e. true productive lifespan, TPL) or other reasons than production (functional productive lifespan, FPL). The objective of the present study was to investigate the influence of milk yield, fat and protein contents, insemination status (INS), somatic cell count (SCC) and β-hydroxybutyrate (BHB) concentration in milk on TPL and FPL. Data included 70,748 Italian Holstein-Friesian cows that calved for the first time between 2014 and 2018. Proportional hazards models assuming a piecewise Weibull distribution of the baseline hazard function, with or without adjustment for milk production, were used to compute relative risks of culling associated with FPL and TPL, respectively. Our study revealed that milk yield, protein and fat contents, INS, SCC and concentration of BHB in milk exhibited significant relationships with TPL and FPL. In particular, the huge difference in risk ratios between high- and low-producing cows confirms the central role of milk production in culling decision-making. In addition, farmers appear more prone to cull cows with several events of high SCC and BHB concentration in milk. HIGHLIGHTS Milk yield, fat and protein contents, insemination status, somatic cell count and ketosis affect productive lifespan in Italian Holstein cows. These factors, therefore, contribute significantly to culling decisions. The identified risk factors of culling can be exploited to improve the current management practices in Italian Holstein Friesian herds and cows’ longevity.

Estimation of milkability breeding values and variance components for Italian Holstein

The importance of milkability as a trait is growing because of the need to efficiently use labor and machinery; therefore, it is crucial to update the statistical model for the trait to improve the accuracy of the estimated breeding values, and thus provide a more accurate tool for decision-making at the farm level. In the Italian Holstein Friesian cattle population, milkability is recorded twice a year by the milk recording system as a binary trait (slow, coded as 2, or not slow, coded as 1). Data consisted of 7,862,371 records from 2,945,249 cows collected between 2004 and 2021. A single-trait threshold animal model with repeated measures was used, with parity, days in milk class, calving season, and regression of production (fat + protein grams) within days in milk class as fixed effects and herd-year-season of recording, permanent environment, and animal as random effects. The results for heritability and repeatability were 0.275 and 0.5, estimated with the Gibbs sampler THRGIBBS1F90. Genomic validation, carried out using genotyped proven bulls born before 2009 as the training set, gave a result of 0.386 for reliability. The genetic correlations of this trait confirmed that both extremes of the estimated breeding value must be treated cautiously, because correlations with important traits such as mastitis resistance, body condition score, and teat length are unfavorable.

Identification of SNPs Associated with Somatic Cell Score in Candidate Genes in Italian Holstein Friesian Bulls.

Simple SummaryMastitis is a worldwide diffused disease usually treated with an excessive use of antibiotics. Therefore, antimicrobial resistance is an important issue to be addressed by scientists. One of the possible solutions to decrease the use of drugs is genetic selection of resistant animals, that is, individuals that can be more resistant to mastitis. In our survey we analyzed Single Nucleotide Polymorphisms (SNPs) in genes known to be involved in both infection resistance and immune system activity. We found a group of SNPs that can be associated to mastitis related phenotypes (namely SCS) and that can be used for selecting resistant animals. An efficient selection is able to improve both animal welfare and quality and safety of animal productsMastitis is an infectious disease affecting the mammary gland, leading to inflammatory reactions and to heavy economic losses due to milk production decrease. One possible way to tackle the antimicrobial resistance issue stemming from antimicrobial therapy is to select animals with a genetic resistance to this disease. Therefore, aim of this study was to analyze the genetic variability of the SNPs found in candidate genes related to mastitis resistance in Holstein Friesian bulls. Target regions were amplified, sequenced by Next-Generation Sequencing technology on the Illumina® MiSeq, and then analyzed to find correlation with mastitis related phenotypes in 95 Italian Holstein bulls chosen with the aid of a selective genotyping approach. On a total of 557 detected mutations, 61 showed different genotype distribution in the tails of the deregressed EBVs for SCS and 15 were identified as significantly associated with the phenotype using two different approaches. The significant SNPs were identified in intergenic or intronic regions of six genes, known to be key components in the immune system (namely CXCR1, DCK, NOD2, MBL2, MBL1 and M-SAA3.2). These SNPs could be considered as candidates for a future genetic selection for mastitis resistance, although further studies are required to assess their presence in other dairy cattle breeds and their possible negative correlation with other traits.

Spatial distance between sites of sampling associated with genetic variation among Neospora caninum in aborted bovine foetuses from northern Italy

BackgroundNeospora caninum, a coccidian protozoan, represents an important cause of bovine abortion. Available N. caninum strains show considerable variation in vitro and in vivo, including different virulence in cattle. To which extent sexual recombination, which is possible in the intestines of domestic dogs and closely related carnivores as definitive hosts, contributes to this variation is not clear yet.MethodsAborted bovine foetuses were collected between 2015 and early 2019 from Italian Holstein Friesian dairy herds suffering from reproductive problems. A total of 198 samples were collected from 165 intensive farms located in Lombardy, northern Italy. N. caninum samples were subjected to multilocus-microsatellite genotyping using ten previously established microsatellite markers. In addition to our own data, those from a recent study providing data on five markers from other northern Italian regions were included and analysed.ResultsOf the 55 samples finally subjected to genotyping, 35 were typed at all or 9 out of 10 loci and their individual multilocus-microsatellite genotype (MLMG) determined. Linear regression revealed a statistically significant association between the spatial distance of the sampling sites with the genetic distance of N. caninum MLMGs (P < 0.001). Including data from this and a previous North Italian study into eBURST analysis revealed that several of N. caninum MLMGs from northern Italy separate into four groups; most of the samples from Lombardy clustered in one of these groups. Principle component analysis revealed similar clusters and confirmed MLMG groups identified by eBURST. Variations observed between MLMGs were not equally distributed over all loci, but predominantly observed in MS7, MS6A, or MS10.ConclusionsOur findings confirm the concept of local N. caninum subpopulations. The geographic distance of sampling was associated with the genetic distance as determined by microsatellite typing. Results suggest that multi-parental recombination in N. caninum is a rare event, but does not exclude uniparental mating. More comprehensive studies on microsatellites in N. caninum and related species like Toxoplasma gondii should be undertaken, not only to improve genotyping capabilities, but also to understand possible functions of these regions in the genomes of these parasites.Graphical

Heat stress and feeding behaviour of dairy cows in late lactation

Heat stress is one of the most important problems that dairy cows have to face and the use of cooling systems is becoming more and more important. The first reaction that has the animal to cope with the environmental variations is to modify its behaviour. This study was aimed to investigate the effect of heat stress and a cooling system on the feeding behaviour of Italian Holstein Friesian dairy cows in late lactation. Two experiments were performed. In the first experiment, eight dairy cows were firstly kept 7 d under thermoneutral condition, and then under mild heat stress (temperature humidity index, THI, ranging between 72 and 78) for others 7 d. The second experiment consisted of 8 dairy cows used in a two-period cross-over design where the treatment was the use or not of a sprinkler system for cooling cows under mild heat stress. Cows were equipped with a noseband pressure sensor able to detect rumination and eating time, number of rumination and eating chews, number of rumination boluses and rumination intensity. Heat stress reduced rumination time, number of rumination chews and boluses (p < .05), and tended to reduce the number of eating chews (p < .10). Cooled cows increased rumination and eating time (p < .05), rumination intensity (p < .01), and the number of rumination and eating chews (p < .05). In conclusion, feeding behaviour was deeply influenced even by mild heat stress, which was effectively improved by the use of a sprinkler system. HIGHLIGHTS Mild heat stress reduced rumination time, number of rumination chews and boluses of dairy cows in late lactation Cooling cows with sprinklers was effective in alleviating heat stress in terms of feeding behaviour

Heritability of Teat Condition in Italian Holstein Friesian and Its Relationship with Milk Production and Somatic Cell Score.

Simple SummaryMammary infections in dairy cattle are still a major problem which impair animal health and jeopardize breeders’ efforts to attain sustainable production. The first natural protection against pathogens ‘access to udder tissue is the teat canal. Teat canal morphology can be influenced by several environmental factors but the present study confirmed the existence of a genetic component. Moreover it was observed that the teat canal morphology is related to milk production and somatic cell count, the latter being an indirect indicator of mammary infections. Considering that the current selection objectives implemented in dairy cattle worldwide have shifted toward a more balanced breeding goal, with a larger emphasis on health traits, a further genetic deterioration in teat condition is not expected.In spite of the impressive advancements observed on both management and genetic factors, udder health still represents one of most demanding objectives to be attained in the dairy cattle industry. Udder morphology and especially teat condition might represent the first physical barrier to pathogens’ access. The objectives of this study were to investigate the genetic component of teat condition and to elucidate its relationship with both milk yield and somatic cell scores in dairy cattle. Moreover, the effect of selection for both milk yield and somatic cell scores on teat condition was also investigated. A multivariate analysis was conducted on 10,776 teat score records and 30,160 production records from 2469 Italian Holstein cows. Three teat scoring traits were defined and included in the analysis. Heritability estimates for the teat score traits were moderate to low, ranging from 0.084 to 0.238. When teat score was based on a four-classes ordinal scoring, its genetic correlation with milk yields and somatic cell score were 0.862 and 0.439, respectively. The scale used to classify teat-end score has an impact on the magnitude of the estimates. Genetic correlations suggest that selection for milk yield could deteriorate teat health, unless more emphasis is given to somatic cell scores. Considering that both at national and international level, the current selection objectives are giving more emphasis to health traits, a further genetic deterioration in teat condition is not expected.

Predicted Feed Efficiency index applied to Italian Holstein Friesian cattle population

Submitted 2020-08-02 | Accepted 2020-09-21 | Available 2020-12-01 https://doi.org/10.15414/afz.2020.23.mi-fpap.326-330 Feed efficiency has a major influence on farm profitability and environmental stewardship in the dairy industry. The aim of this study was to describe a new selection index adopted by the Italian Holstein and Jersey Association (ANAFIJ, Cremona, Italy) to improve feed efficiency using data recorded by the official dairy recording system. Predicted dry matter intake (pDMI) was derived from milk yield, fat content, and estimated cow body weight. Fat-protein corrected milk (FPCM) was derived from milk yield corrected for fat, protein, and a fixed coefficient for lactose content (4.80%). Therefore, the predicted feed efficiency (pFE) was estimated as ratio between FPCM and pDMI. Average pFE was 1.27±0.18 (kg.d -1 ) with heritability of 0.32. Predicted Feed Efficiency index (pFEi), traditional and genomic, has been implemented in the Italian Holstein Friesian evaluation system. Results suggest that pFEi may be a new breeding objective for Italian Friesians. The official selection index (PFT), in use since 2002, is positively correlated with pFEi. However, the introduction of pFEi will improve the positive feed efficiency trend. This approach will permit the Italian Holstein Friesian breeders to improve feed efficiency, without increasing costs of recording system. However, to avoid the risk of selecting animals with an excessive negative energy balance after calving, it would be useful to include in the pFE a correction for body condition score and reproductive performances. Meanwhile, in order to increase the accuracy of the predicted phenotype, an Italian consortium is creating a consistent phenotypic critical mass of individual data for dry matter intake in cows, heifers and young bulls. Keywords: feed efficiency, cattle breeding, dry matter intake, breeding value estimation References Cassandro, M. (2020). Animal breeding and climate change, mitigation and adaptation. Journal of Animal Breeding and Genetics, 137(2), 121-122. https://doi.org/10.1111/jbg.12469 Cassandro, M. et al. (2010). Genetic parameters of predicted methane production in Holstein Friesian cows. Proceedings of the 9th World Congress on Genetics Applied to Livestock Production, Leipzig, Germany. Cassandro, M., Mele, M. and Stefanon, B. (2013). Genetic aspects of enteric methane emission in livestock ruminants. Italian Journal of Animal Science, 12(3), 450-458. De Haas, Y. et al. (2012). Improved accuracy of genomic prediction for dry matter intake of dairy cattle from combined European and Australian data sets. Journal of Dairy Science, 95(10), 6103-6112. De Vries, M. and Veerkamp, R. (2000). Energy balance of dairy cattle in relation to milk production variables and fertility. Journal of Dairy Science, 83(1), 62-69. Finocchiaro, R. et al. (2017). Body weight prediction in Italian Holstein cows. ICAR Technical Series, 22, 95-98. Hegarty, R. et al. (2007). Cattle selected for lower residual feed intake have reduced daily methane production. Journal of Animal Science, 85(6), 1479-1486. Hurley, A. M. et al. (2018). Characteristics of feed efficiency within and across lactation in dairy cows and the effect of genetic selection. Journal of Dairy Science, 101(2), 1267-1280. https://doi.org/https://doi.org/10.3168/jds.2017-12841 Meuwissen, T. H., Hayes, B. J. and Goddard, M. E. (2001). Prediction of total genetic value using genome-wide dense marker maps. Genetics, 157(4), 1819-1829. National Research Council. (2001). Nutrient Requirements of Dairy Cattle: Seventh Revised Edition, 2001. The National Academies Press. http://www.nap.edu/catalog.php?record_id=9825 Pryce, J. et al. (2014). Genomic selection for feed efficiency in dairy cattle. Animal, 8(1), 1-10. Sjaunja, L. et al. (1990). A Nordic proposal for an energy corrected milk formula. Proceedings of the 2nd Session of Committee for Recording and Productivity of Milk Animal, Paris, p. 156. Veerkamp, R. et al. (2000). Genetic correlation between days until start of luteal activity and milk yield, energy balance, and live weights. Journal of Dairy Science, 83(3), 577-583. Verbyla, K. et al. (2010). Predicting energy balance for dairy cows using high-density single nucleotide polymorphism information. Journal of Dairy Science, 93(6), 2757-2764. Wall, E., Coffey, M. and Brotherstone, S. (2007). The relationship between body energy traits and production and fitness traits in first-lactation dairy cows. Journal of Dairy Science, 90(3), 1527-1537. Wallace, R. J. et al. (2019). A heritable subset of the core rumen microbiome dictates dairy cow productivity and emissions. Science Advances, 5(7), eaav8391.

Effect of Heat Stress on Dairy Cow Performance and on Expression of Protein Metabolism Genes in Mammary Cells.

Simple SummaryEnvironmental temperatures are increasing, and consequent global warming also has negative effects on dairy cattle farms, which may result in reduced production and poorer milk quality. The protein content of casein, in particular, is important in influencing the coagulation properties of milk and, therefore, the production and quality of cheese. The aim of this study was to assess the effect of heat stress on animal performance and on the expression of selected genes involved in milk protein metabolism. Eight dairy cows were kept under thermoneutral conditions for 8 days. The same animals were then maintained under mild heat stress conditions for an additional 8 days. The results of this study revealed that mild heat stress reduced the feed intake and performance of dairy cows in terms of milk and protein yield, but not the expression of the target genes involved in milk protein metabolism, such as those coding for caseins.The aim of this study was to assess the effect of heat stress on dairy cow performance and on the expression of selected genes involved in milk protein metabolism. Eight Italian Holstein Friesian cows were kept under thermoneutral conditions (temperature–humidity index (THI) < 72, CON) for 8 days and under mild heat stress conditions (72 < THI < 78, HS) for an additional 8 days. The rectal temperature, feed intake, and milk yield were recorded during the last 3 days of the CON and HS periods. During the same time period, milk samples were collected to assess the composition and expression of selected genes involved in milk protein metabolism. Gene expression analyses were performed on somatic cells from milk, which are representative of mammary tissue. In terms of dairy cow performance, HS resulted in lower milk and protein yields and feed intake but higher rectal temperature than for CON (p < 0.05). Under HS, there were greater abundances of HSPA1A (p < 0.05) and BCL2 (p < 0.05), compared to CON, but similar levels of CSN2 (p > 0.05), CSN3 (p > 0.05), HSPA8 (p > 0.05), and STAT5B (p > 0.05) mRNA. Mild heat stress reduced the performance of dairy cows without affecting the expression of genes coding for caseins.

Frequencies Evaluation of β-Casein Gene Polymorphisms in Dairy Cows Reared in Central Italy.

Simple SummaryBovine milk contains several β-casein variants, with the A1 and A2 variants occurring most frequently. The presence of some variants, such as A1, B, and C, is considered a risk factor for disease in humans who consume milk. These variants are probably involved in intolerance to milk and some human diseases due to the production of a bioactive peptide with opioid activity during digestion, β-casomorphin 7 (BCM-7). In contrast, the A2 variant is not involved in pathogenetic mechanisms; thus, its presence in milk is a desirable feature. The difference between the A1 and A2 variants is a mutation at position 67 of the β-casein gene (CSN2), which causes an amino acid to change from histidine (in the A1, B, and C variants) to proline (in the A2 variant). To select dairy cows on the basis of the presence of the β-casein variant A2, allele frequencies of CSN2 variants were evaluated in Italian dairy cows reared in central Italy. The results of this study may help with the selection of animals with the β-casein gene variant A2 to produce a more digestible milk that only contains the β-casein variant A2.The majority of proteins in cow’s milk are caseins, which occur in four groups (α-s1, α-s2, β, and k) encoded by different genes (CSN1S1, CSN1S2, CSN2, and CSN3, respectively). In this study, we focused on the β-casein allele variants A1 and A2 due to their influence on milk’s technological characteristics and human health. Digestion of the β-casein variant A1 leads to the formation of β-casomorphin 7 (BCM-7), a bioactive peptide that has been suggested to be a possible cause of various human diseases and associated with low milk digestibility. The potential negative role of the β-casein variant A1 in human health has stimulated the planning of cattle breeding programs based on genetic selection to increase the frequency of the A2 variant, which is associated with increased milk digestibility. The aim of this work was to evaluate the frequencies of the different β-casein variants in Italian Holstein Friesian dairy cows from cattle farms located in central Italy to select a population of A2 homozygous animals. β-casein genotypes were identified by evaluating the presence of single nucleotide polymorphisms (SNPs) of the CSN2 gene using PCR and sequencing analysis. The frequency of the desirable β-casein variant A2 in the studied bovine population was 0.61. The frequency of the undesirable A1 variant in the studied bovine population was 0.30. The frequency of the A2 allele was higher than expected for the breed; therefore, genetic selection for the A2 variant in these animals could be achieved in a fairly short time using A2 homozygous bulls.

112 Identification of Solute Carrier Family 5 Member 9 (SLC5A9) as Biomarker of In Vivo and In Vitro Oocyte Developmental Competence

The transcriptome associated with the ability of oocytes to support embryogenesis and development remains unclear. The aim of this study was to compare the mRNA expression pattern between oocytes collected from fertile heifers (H) and repeat breeders (RB) using RNAseq. Oocytes were collected by ovum pick-up from Italian Simmental (IS) and Holstein Friesian (HF) heifers that became pregnant at the following oestrus, and from cows of the same breeds classified as RB after they failed to become pregnant for a minimum of 3 consecutive AI. Oocytes from each animal (5 for HF_RB, 3 each for all other groups) were pooled and sequenced using Illumina HiSEqn 2000 (Illumina Inc., San Diego, CA, USA). Principal component analysis showed that HF oocytes clustered away from those of IS, irrespective of the fertility status. However, within breeds, H and RB always clustered apart from each other. This suggests that differences in the transcriptional blueprint between breeds was more prominent than differences related to fertility. However, these were still strong when considering breeds separately, therefore we treated breeds as independent groups and performed differential expression analysis on H v. RB in IS and HF. DESEqn 2 identified 135 differentially expressed genes when we compared H and RB in IS and 2124 in HF. This difference in number of DE genes between the 2 breeds reflects the fact that the variance between H and RB transcriptional patterns in HF is larger than in IS. We looked for genes that were differentially and consistently expressed between H and RB in both breeds and identified 10 genes: histone H2B, exo/endonuclease G, solute carrier family 5 member 9, BH3 interacting domain death agonist, TBK1 binding protein 1, purine-rich element binding protein A, tRNA-yW synthesising protein 1 homologue, Jun oncogene, FRA10AC1 homologue, and SKI oncogene. To validate their potential use as biomarkers, we performed a preliminary in vitro validation by RT-qPCR. As described in the literature, oocytes collected from ovaries with more than 10 follicles of 2 to 6 mm were classified as high quality, while those collected from ovaries with fewer than 10 follicles were classified as low quality (Gandolfi et al. 1997 Theriogenology 48, 1153-1160). Gene expression analysis confirmed SLC5A9, a membrane-bound protein involved in sodium-dependent transport of glucose, as a potential biomarker to discriminate between a competent and incompetent oocyte. Altogether, our data provide a detailed overview of the mRNA pattern defining the differences between a competent and incompetent oocyte in vivo, and identified a new potential marker able to differentiate fertile and infertile oocyte both in vivo and in vitro. Study supported by PRIN 08–09, EU-Quantomics no. 222664 and Carraresi Foundation.

Analysis of non-return rate in Italian Holstein Friesian bulls

Until recently non-return rate 56 days (NR56) for Italian Holstein Friesian bulls had been published only for artificial-insemination (AI) organizations. Since December 2015, the information about sire fertility has been published also for the farmers. The objectives of this research were to assess the importance of information about the cow’s age at insemination and editing of age of bulls for improving prediction of bull fertility. The intent was to revise the old model, even if NR56 is a phenotypic assessment of bull’s prospective fertility and not a genetic evaluation. Factors considered for the revision of the model were date of insemination, age of cows at the time of mating and number of matings. Data included 3,726,450 records from 3,210 bulls and 1,312,901 cows in 7,395 herds from January 2011 till January 2016. Results revealed that alternative models ignoring AI organization and using only last five years of insemination, multiple services and editing on age of bull improved accuracy of predictions.

Investigating mutual relationship among milk fatty acids by multivariate factor analysis in dairy cows

The interpretation of mutual relationship among milk fatty acids (FA) is not easy due to the high number of FA contained in milk fat and to the high degree of correlation among them. Multivariate analysis includes different statistical approaches that could help explaining complex pattern of variables. In this study, Multivariate Factor Analysis (MFA) was used to decompose the correlation matrix of 47 FA and milk production traits (milk yield and protein and fat content) measured in 300 Italian Holstein Friesian cows reared in the North of Italy in 23 commercial dairy farms, representative of the intensive dairy system. MFA was able to extract seven latent factors with specific biologic meaning: secretion of Long Chain FA (KLCFA), mammary FA de novo synthesis (Km), rumen biohydrogenation (Kbh), synthesis of odd chain FA (Ko), synthesis of branched chain FA (Kb), mammary desaturation activity (Kd), milk yield (Kmy). According to the pattern of communalities of the factor analysis, C18:3c9c12c15 was the only FA, along with C18:2t11c15, to be uncorrelated with the other variables and it seemed to be excluded by the metabolic pattern described by the seven factors. The desaturation products of the SCD enzyme were independently associated to three latent factors, suggesting new insights in the regulation of SCD activity. Factors were considered as new quantitative phenotypes related to prominent features of milk FA profile. With the aim of evaluating the feeding regimen and animal effects, latent factors were analysed with a mixed model, which considered the fixed effect of lactation stage, parity, some feeding regimen characteristics and the random effect of bull. Lactation stage significantly affected Km and Kmy factors. In perspective, the seven factors extracted by applying MFA analysis to milk FA composition could be considered as new and more informative traits to test the effect of endogenous and exogenous variation factors.

Prediction of gross feed efficiency in Italian Holstein Friesian bulls

Prediction of gross feed efficiency in Italian Holstein Friesian bulls

Evaluation of Some Physical, Haemathological and Clinical Chemistry Parameters in Healthy Newborn Italian Holstein Calves

The aim of the present study was to investigate some physical, haematological and clinical chemistry parameters in the newborn Italian Holstein calf at birth and at 24 h of life, to evaluate changes during the immediate post-partum period. Forty-six Italian Holstein Friesian calves were included in this study. Heart rate, respiratory rate and body temperature were recorded at birth and at 24 h of life. The time needed to raise the head, acquire sternal recumbency, stand up were also recorded. Blood samples were collected before first feeding and at 24 h of age and CBC count, L-lactate, glucose and total protein concentrations were evaluated. The head was raised immediately in 46/46 calves, suckling reflex was acquired within 12±9 min, sternal position in 5±2 min and newborn stood up in 38±30 min. Some of the physical data, haematological and biochemical values showed statistical differences between birth and 24 h of age. The results from this study provide some information about physical and laboratory data of Italian Holstein Friesian calves, at birth and at 24 h of life. Our results confirm that several clinical and laboratory values in newborn calves differ from adult reference intervals and from calves of different breeds.

Genetic Parameters of Fatty Acids in Italian Brown Swiss and Holstein Cows

The aim of this study was to estimate the genetic parameters and to predict experimental breeding values (EBVs) for saturated (SFA), unsaturated (UFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids, the ratio of fatty acids, and the productive traits in Italian Brown Swiss (BSW) and Holstein Friesian (HOL) cattle. Test-day yields from 235,658 HOL and 21,723 BSW cows were extracted from the Italian HOL and BSW Associations databases from November 2009 to October 2012 out of 3310 herds. The milk samples collected within the routine milk recording scheme were processed with the Milkoscan™ FT 6500 Plus (Foss, Hillerød, Denmark) for the identification of SFA, UFA, MUFA and PUFA composition in milk. Genetic parameters for fatty acids and productive traits were estimated on 1,765,552 records in HOL and 255,592 records in BSW. Heritability values estimated for SFA, UFA, MUFA and PUFA ranged from 0.06 to 0.18 for the BSW breed and from 0.10 to 0.29 for HOL. The genetic trends for the fatty acids were consistent between traits and breeds. Pearson’s and Spearman’s correlations among EBVs for SFA, UFA, MUFA and PUFA and official EBVs for fat percentage were in the range 0.32 to 0.54 for BSW and 0.44 to 0.64 for HOL. The prediction of specific EBVs for milk fatty acids and for the ratio among them may be useful to identify the best bulls to be selected with the aim to improve milk quality in terms of fat content and fatty acid ratios, achieving healthier dairy productions for consumers.

Temporal Variation in Genetic Diversity and Population Structure of Burlina Cattle Breed

We analysed the temporal variation of inbreeding, genetic variability and population structure in the Burlina (BUR) cattle breed. A total of 279 individuals were chosen for the analysis representing a period of 19 years (1991-2010) and analysed using 24 microsatellite markers. A total of 235 alleles were detected in the population with a mean of 9.79±3.91 alleles per locus. In the 19-year period, a stable pattern in the mean number of alleles was found. The mean observed heterozygosity was 0.63 and it was slightly lower than the expected in all birth year groups. Neither an increase nor a decrease in heterozygosity and inbreeding estimates were detected over the years, with the exception of the FIS index which was close to zero in two birth year groups: 2001-2002 and 2006. Absence of bottleneck events was proved and structure analysis revealed an increase in breed complexity over the years and a clear differentiation with the Italian Holstein Friesian cattle breed. Molecular markers were successfully applied in the monitoring of the genetic variability of BUR thus enabling the planning and the application of strategies for the in situ conservation of genetic resources and the improving of breed identity.

Genetic parameters for body condition score, locomotion, angularity, and production traits in Italian Holstein cattle

The objectives of this research were to estimate genetic parameters for body condition score (BCS) and locomotion (LOC), and to assess their relationships with angularity (ANG), milk yield, fat and protein content, and fat to protein content ratio (F:P) in the Italian Holstein Friesian breed. The Italian Holstein Friesian Cattle Breeders Association collects type trait data once on all registered first lactation cows. Body condition score and LOC were introduced in the conformation scoring system in 2007 and 2009, respectively. Variance (and covariance) components among traits were estimated with a Bayesian approach via a Gibbs sampling algorithm and an animal model. Heritability estimates were 0.114 and 0.049 for BCS and LOC, respectively. The genetic correlation between BCS and LOC was weak (−0.084) and not different from zero; therefore, the traits seem to be genetically independent, but further investigation on possible departures from linearity of this relationship is needed. Angularity was strongly negatively correlated with BCS (−0.612), and strongly positively correlated with LOC (0.650). The genetic relationship of milk yield with BCS was moderately negative (−0.386), and was moderately positive (0.238) with LOC. These results indicate that high-producing cows tend to be thinner and tend to have better locomotion than low-producing cows. The genetic correlation of BCS with fat content (0.094) and F:P (−0.014) was very weak and not different from zero, and with protein content (0.173) was weak but different from zero. Locomotion was weakly correlated with fat content (0.071), protein content (0.028), and F:P (0.074), and correlations were not different from zero. Phenotypic correlations were generally weaker than their genetic counterparts, ranging from −0.241 (BCS with ANG) to 0.245 (LOC with ANG). Before including BCS and LOC in the selection index of the Italian Holstein breed, the correlations with other traits currently used to improve type and functionality of animals need to be investigated.

Genetic response for milk production traits, somatic cell score, acidity and coagulation properties in Italian Holstein–Friesian population under current and alternative selection indices and breeding objectives

The aim of this work was to estimate the annual genetic response for milk yield (MY), milk components, somatic cell score (SCS), milk acidity and milk coagulation properties (MCP: rennet coagulation time, RCT; curd firmness 30min after rennet addition, a30) in Italian Holstein–Friesian (IHF) population under different selection indices and breeding objectives. Current selection index (PFTSI) of IHF breed includes fat (FY) and protein (PY) yields, fat (F%) and protein (P%) percentages, and SCS. Annual genetic response (GRy) for the aforementioned traits and correlated response for MCP, MY and milk acidity were estimated using selection index theory. Genetic parameters for all traits were assumed from different sources and validated for positive definite matrix. Alternative selection indices were simulated by adding MCP as direct (MCPd) or predicted (MCPp) traits to current selection index. Direct measures were assumed to be recorded in laboratory by computerized renneting meter, whereas predicted measures by mid-infrared spectroscopy (MIRS). Current breeding objective (PFTBO) includes FY, PY, F%, P% and SCS with relative emphasis of 13.6, 61.0, 3.4, 5.1 and −16.9%, respectively. Six alternative breeding objectives were formulated according to the relative weight given to MCP: 5% (MCP5%), 12.5% (MCP12.5%), 25% (MCP25%), 50% (MCP50%), 75% (MCP75%) and 100% (MCP100%). Current selection index does not affect significantly MCP traits, whereas MCPp to improve MCP12.5% resulted in a gain of about 0.10 genetic standard deviations per year for both RCT and a30, without losses in GRy for MY, FY and PY. The inclusion of MCP traits in the selection index of IHF is expected to increase casein to protein ratio and to decrease SCS.