Aligning health and welfare principles and practice in organic dairy systems: a review

This review provides an assessment of research findings into the current practices and standards and the principles and aspirations for organic dairy production, with respect to the health and welfare of the dairy cow. The relationships between the four main factors: management, environment, genetics and nutrition and their impact on the health and welfare status of organic dairy cows are considered. The concept that good animal health and welfare is more than merely the absence of disease, with behavioural aspects of health and welfare such as physiological and psychological needs, is also discussed. These factors are inter-related and important in all dairy systems, irrespective of whether the system is organic, low-input or intensive. Incidences of individual clinical and sub-clinical diseases that are recorded in conventional dairy systems also occur in organic dairy systems, with infertility, lameness and mastitis being the major problems. However, the magnitude of the incidence of many of these diseases may be either lower or higher in organic systems due to different management practices and the standards defined for organic milk production that, for example, prohibit the routine use of conventional medicines and require the feeding of high-forage diets. In relation to different systems, it is important to note that contrary to a common assumption, good welfare does not necessarily occur with more extensive systems. The type of organic system (self-sufficient, purchased-feed) also has the potential to have a major influence on the incidence of health problems and the reproductive status of organic dairy herds. Health status is also influenced by environmental and welfare factors, including the method of rearing replacement animals, type of housing and the geographical and climatic conditions of individual farms. Overall, this review identifies where conflicts arise between current practice and the organic principles and standards, and aims to provide suggestions to bring about further improvement in organic dairy health and welfare.     

A comparison of two different approaches to inventory analysis of dairies

Two different methods for Life Cycle Inventory (LCI) applied to the dairy industry was performed at two dairies. In the simplified method, total environmental loads from a dairy was registred and allocated to liquid milk. Energy and emissions are measured for each process step for the detailed method. Both methods have advantages and disadvantages. The simplified method captures all energy and emissions of dairy processing, but treats the dairy as a “black box”. The energy consumption was found to be 1, 27 MJ/1 and 2,55 MJ/1 for the two dairies. By use of the detailed method it is easy to “loose” information, and it is very time consuming. The energy consumption was lower than for the simplified method. The environmental loads can on the other hand be divided on the different process steps. The main conclusion is that choice of method depends on the purpose of the LCA-study.     

Environmental analysis of packaging‐derived changes in food production and consumer behavior

This study analyzed the environmental impacts of packaging‐derived changes in food production and consumer behavior to assist packaging designers in making environmentally conscious decisions. Packaging can be functionalized to prevent food loss and waste (FLW), for example, extending the expiration date and apportioning the package size, but it can generate additional environmental impacts from changes in food and packaging production. Previous studies assessed additional impacts from packaging production; however, the effects of packaging functionalization are yet to be connected with food production and consumer behavior. To examine the effect of functionalization on these aspects, we analyzed packaging‐derived changes in food production for milk and cabbage products. The case study compared products with functionalized packaging that permits a longer expiration date or a smaller portion size to their base‐case products. Our results showed that the packaging‐derived changes increased the global warming potential (GWP) of food production more than other processes did. Thus, changes in food production weakened the effectiveness of the packaging functionalization to decrease the GWP. Moreover, the analysis of consumer behavior scenarios showed that consumers’ perception of the expiration date decisively influences the effectiveness of packaging functionalization. When consumers discarded food after the expiration date, provided they consumed in small quantities, the packaging functionalization reduced FLW. From the scenario analysis, we identified appropriate combinations of packaging functionalization and consumer behaviors to effectively decrease total GWP. With our expanded analysis, packaging designers can understand the effectiveness of their decisions on the product life cycle in reducing FLW and environmental impacts.     

Does increasing milk yield per cow reduce greenhouse gas emissions? A system approach

Milk yield per cow has continuously increased in many countries over the last few decades. In addition to potential economic advantages, this is often considered an important strategy to decrease greenhouse gas (GHG) emissions per kg of milk produced. However, it should be considered that milk and beef production systems are closely interlinked, as fattening of surplus calves from dairy farming and culled dairy cows play an important role in beef production in many countries. The main objective of this study was to quantify the effect of increasing milk yield per cow on GHG emissions and on other side effects. Two scenarios were modelled: constant milk production at the farm level and decreasing beef production (as co-product; Scenario 1); and both milk and beef production kept constant by compensating the decline in beef production with beef from suckler cow production (Scenario 2). Model calculations considered two types of production unit (PU): dairy cow PU and suckler cow PU. A dairy cow PU comprises not only milk output from the dairy cow, but also beef output from culled cows and the fattening system for surplus calves. The modelled dairy cow PU differed in milk yield per cow per year (6000, 8000 and 10 000 kg) and breed. Scenario 1 resulted in lower GHG emissions with increasing milk yield per cow. However, when milk and beef outputs were kept constant (Scenario 2), GHG emissions remained approximately constant with increasing milk yield from 6000 to 8000 kg/cow per year, whereas further increases in milk yield (10 000 kg milk/cow per year) resulted in slightly higher (8%) total GHG emissions. Within Scenario 2, two different allocation methods to handle co-products (surplus calves and beef from culled cows) from dairy cow production were evaluated. Results showed that using the 'economic allocation method', GHG emissions per kg milk decreased with increasing milk yield per cow per year, from 1.06 kg CO2 equivalents (CO2eq) to 0.89 kg CO2eq for the 6000 and 10 000 kg yielding dairy cow, respectively. However, emissions per kg of beef increased from 10.75 kg CO2eq to 16.24 kg CO2eq due to the inclusion of suckler cows. This study shows that the environmental impact (GHG emissions) of increasing milk yield per cow in dairy farming differs, depending upon the considered system boundaries, handling and value of co-products and the assumed ratio of milk to beef demand to be satisfied.     

Packaging Strategies That Save Food: A Research Agenda for 2030

Thoroughly considering and optimizing packaging systems can avoid food loss and waste. We suggest a number of issues that must be explored and review the associated challenges. Five main issues were recognized through the extensive experience of the authors and engagement of multiple stakeholders. The issues promoted are classified as follows: (1) identify and obtain specific data of packaging functions that influence food waste; (2) understand the total environmental burden of product/package by considering the trade‐off between product protection and preservation and environmental footprint; (3) develop understanding of how these functions should be treated in environmental footprint evaluations; (4) improve packaging design processes to also consider reducing food waste; and (5) analyze stakeholder incentives to reduce food loss and waste. Packaging measures that save food will be important to fulfill the United Nations Sustainable Development goal to halve per capita global food waste at the retail and consumer levels and to reduce food losses along production and supply chains.     

Mapping the Influence of Food Waste in Food Packaging Environmental Performance Assessments

Scrutiny of food packaging environmental impacts has led to a variety of sustainability directives, but has largely focused on the direct impacts of materials. A growing awareness of the impacts of food waste warrants a recalibration of packaging environmental assessment to include the indirect effects due to influences on food waste. In this study, we model 13 food products and their typical packaging formats through a consistent life cycle assessment framework in order to demonstrate the effect of food waste on overall system greenhouse gas (GHG) emissions and cumulative energy demand (CED). Starting with food waste rate estimates from the U.S. Department of Agriculture, we calculate the effect on GHG emissions and CED of a hypothetical 10% decrease in food waste rate. This defines a limit for increases in packaging impacts from innovative packaging solutions that will still lead to net system environmental benefits. The ratio of food production to packaging production environmental impact provides a guide to predicting food waste effects on system performance. Based on a survey of the food LCA literature, this ratio for GHG emissions ranges from 0.06 (wine example) to 780 (beef example). High ratios with foods such as cereals, dairy, seafood, and meats suggest greater opportunity for net impact reductions through packaging‐based food waste reduction innovations. While this study is not intended to provide definitive LCAs for the product/package systems modeled, it does illustrate both the importance of considering food waste when comparing packaging alternatives, and the potential for using packaging to reduce overall system impacts by reducing food waste.     

Environmental Sustainability of Fluid Milk Delivery Systems in the United States

Beverage producers in the United States choose packaging based on cost and consumer preference. Monolayer high‐density polyethylene (HDPE) and gable‐top carton containers have long dominated the U.S. fluid milk market, but pressure for more sustainable packaging is increasing. We present a broad discussion on environmental sustainability of 18 fluid milk containers through life cycle assessment. Because different container types require unique milk processing, distribution, and disposal and incur or avoid milk losses, fluid milk delivery systems (FMDSs) are evaluated, rather than containers in isolation. By assessing FMDSs, a complete measure of containers’ environmental sustainability was obtained. Despite conservative assumptions about milk losses, differences in container size, milk processing, distribution, and container recycling, pair‐wise cradle‐to‐grave comparisons of FMDSs show there are no superior FMDSs. But, 500‐ to 1,000‐milliliter FMDSs are potentially superior to ≥half gallon if they prevent milk losses. Thus, the future of FMDSs in the United States depends on the industry's ability to prevent distribution (12%) and consumption milk losses (20% to 35%). Farm‐gate‐to‐grave comparisons showed that chilled HDPE FMDSs are superior to other plastic and chilled paperboard FMDSs for climate‐change impact, but the result is inconclusive for chilled HDPE to ambient (unrefrigerated) paperboard or plastic pouch FMDS comparisons. Plastic pouch FMDSs show potential to reduce nonrenewable fossil energy, but need to be recyclable. Ambient FMDSs are superior to chilled FMDSs for water depletion. Eight‐ounce paperboard FMDSs are superior to 8‐ounce plastic FMDSs. Thus, alternative FMDSs may improve environmental sustainability of the U.S. postfarm fluid milk supply chain.     

Genome‐wide association analysis and gene set enrichment analysis with SNP data identify genes associated with 305‐day milk yield in Holstein dairy cows

Milk production traits, such as 305‐day milk yield (305MY), have been under direct selection to improve production in dairy cows. Over the past 50 years, the average milk yield has nearly doubled, and over 56% of the increase is attributable to genetic improvement. As such, additional improvements in milk yield are still possible as new loci are identified. The objectives of this study were to detect SNPs and gene sets associated with 305MY in order to identify new candidate genes contributing to variation in milk production. A population of 781 primiparous Holstein cows from six central Washington dairies with records of 305MY and energy corrected milk were used to perform a genome‐wide association analysis (GWAA) using the Illumina BovineHD BeadChip (777 962 SNPs) to identify QTL associated with 305MY (P < 1.0 × 10^?5). A gene set enrichment analysis with SNP data (GSEA‐SNP) was performed to identify gene sets (normalized enrichment score > 3.0) and leading edge genes (LEGs) influencing 305MY. The GWAA identified three QTL comprising 34 SNPs and 30 positional candidate genes. In the GSEA‐SNP, five gene sets with 58 unique and 24 shared LEGs contributed to 305MY. Identification of QTL and LEGs associated with 305MY can provide additional targets for genomic selection to continue to improve 305MY in dairy cattle.     

Guidance for Improving Life-Cycle Design and Management of Milk Packaging

Life-cycle inventory and cost-analysis tools applied to milk packaging offer guidelines for achieving better environmental design and management of these systems. Life-cycle solid waste, energy, and costs were analyzed for seven systems including single-use and refillable glass bottles, single-use and refillable high-density polyethylene (HDPE) bottles, paperboard gable-top cartons, linear low-density polyethylene (LLDPE) flexible pouches, and polycarbonate refillable bottles on a basis of 1,000 gal of milk delivered. In addition, performance requirements were also investigated that highlighted potential barriers and trade-offs for environmentally preferable alternatives. Sensitivity analyses, indicated that material production energy, postconsumer solid waste, and empty container costs were key parameters for predicting life-cycle burdens and costs. Recent trends in recycling rates, tipping fees, and recycled materials market value had minimal effect on the results. Inventory model results for life-cycle solid waste and energy indicated the same rank order as results from previously published life-cycle inventory studies of container systems.
Refillable HDPE and polycarbonate, and the flexible pouch were identified as the most environmentally preferable with respect to life-cycle energy and solid waste. The greater market penetration of these containers may be limited by performance issues such as empty container storage, handling requirements, and deposit fees for refillables, and resealability and puncture resistance for the pouch.     

System expansion and allocation in life cycle assessment of milk and beef production

Background, Goal and Scope  System expansion is a method used to avoid co-product allocation. Up to this point in time it has seldom been used in LCA studies of food products, although food production systems often are characterised by closely interlinked sub-systems. One of the most important allocation problems that occurs in LCAs of agricultural products is the question of how to handle the co-product beef from milk production since almost half of the beef production in the EU is derived from co-products from the dairy sector. The purpose of this paper is to compare different methods of handling co-products when dividing the environmental burden of the milk production system between milk and the co-products meat and surplus calves. Main Features  This article presents results from an LCA of organic milk production in which different methods of handling the co-products are examined. The comparison of different methods of co-product handling is based on a Swedish LCA case study of milk production where economic allocation between milk and meat was initially used. Allocation of the co-products meat and surplus calves was avoided by expanding the milk system. LCA data were collected from another case study where the alternative way of producing meat was analysed, i.e. using a beef cow that produces one calf per annum to be raised for one and a half year. The LCA of beef production was included in the milk system. A discussion is conducted focussing on the importance of modelling and analysing milk and beef production in an integrated way when foreseeing and planning the environmental consequences of manipulating milk and beef production systems. Results  This study shows that economic allocation between milk and beef favours the product beef. When system expansion is performed, the environmental benefits of milk production due to its co-products of surplus calves and meat become obvious. This is especially connected to the impact categories that describe the potential environmental burden of biogenic emissions such as methane and ammonia and nitrogen losses due to land use and its fertilising. The reason for this is that beef production in combination with milk can be carried out with fewer animals than in sole beef production systems. Conclusion, Recommendation and Perspective  Milk and beef production systems are closely connected. Changes in milk production systems will cause alterations in beef production systems. It is concluded that in prospective LCA studies, system expansion should be performed to obtain adequate information of the environmental consequences of manipulating production systems that are interlinked to each other.     

Comparison of types and antimicrobial susceptibility of Staphylococcus from conventional and organic dairies in west-central Minnesota, USA

Aims:  To assess whether conventional and organic dairy management practices are associated with differences in the susceptibility of Staphylococcus to antimicrobial agents.
Methods and Results:  Staphylococcus was isolated from milk samples collected from conventional and organic dairies in west-central Minnesota. Isolates were categorized as (1) coagulase-positive, (2) novobiocin-sensitive coagulase-negative or (3) novobiocin-resistant coagulase-negative. Novobiocin-resistant coagulase-negative Staphylococcus (CNS) was more common on conventional farms and novobiocin-sensitive CNS predominated the isolates from organic farms. Overall, a larger proportion of isolates from organic rather than conventional farms were susceptible to erythromycin, pirlimycin and tetracycline. However, for pirlimycin and tetracycline, different patterns of susceptibility were observed among Staphylococcus categories.
Conclusion:  In this study, organic dairy management was associated with more overall antimicrobial susceptibility among Staphylococcus than was conventional management. However, different patterns of susceptibility among Staphylococcus categories suggest that multiple management practices, including some unrelated to antimicrobial use, may contribute to the observed differences in susceptibility.
Significance and Impact of the Study:  This study adds to our understanding of the implications of dairy management choices.     

Life cycle assessment of bread produced on different scales

A case study of white bread has been carried out with the purpose of comparing different scales of production and their potential environmental effects. The scales compared are: home baking, a local bakery and two industrial bakeries with distribution areas of different sizes. Data from the three bakeries and their suppliers have been collected. The systems investigated include agricultural production, milling, baking, packaging, transportation, consumption and waste management. Energy use and emissions have been quantified and the potential contributions to global warming, acidification, eutrophication and photo-oxidant formation have been assessed. The large industrial bakery uses more primary energy and contributes more to global warming, acidification and eutrophication than the other three systems. The home baking system shows a relatively high energy requirement; otherwise, the differences between home baking, the local bakery and the small industrial bakery are too small to be significant.     

Survey of Shiga toxigenic Escherichia coli O157 and drug-resistant coliform bacteria from in-line milk filters on dairy farms in the Czech Republic

Aims: To determine the occurrence of Shiga toxin‐producing Escherichia coli (STEC) O157 and coliform bacteria isolates resistant to antimicrobial agents in dairy herds by examining milk filters and to analyse the influence of management factors and antibiotic use on antimicrobial resistance. Methods and Results: A total of 192 in‐line milk filters were sampled on 192 dairy farms in the Czech Republic. Information on feeding, husbandry, production, and antibiotic therapy were obtained by questionnaire. The milk filters were cultured for STEC O157 and coliform bacteria. All recovered isolates were examined for antimicrobial susceptibility and presence of antimicrobial‐resistance genes. STEC O157 was detected in four (2%) of the filters. Resistant nonpathogenic E. coli and coliform bacteria isolates with specific genes were detected in 44 (23%) of the filters. Conclusions: The study demonstrated a high prevalence of resistant coliform bacteria in milk filters obtained on Czech dairy farms. Significance and Impact of the Study: The occurrence of resistant coliform bacteria in milk filters was significantly higher among isolates from farms where antibiotic therapy against mastitis was employed during the dry period (P < 0·05).     

内蒙古牧区乳与乳制品中乳酸菌资源及其生态分布

从代表内蒙古牧区不同地域特点和独特生态环境的9个盟市18个牧业旗519户牧民家庭,使用目的采样和层次分类随机采样相结合的方法,共采集鲜乳及乳制品样品752份,分离到947株乳酸菌,并通过形态、染色、培养特性及生化反应等实验对其进行了鉴定,有765株实验菌株分别归于7个属50个种和亚种,其中归于乳杆菌属的有28个种和亚种;归于双歧杆菌属的有2个种;归于肠球菌属的有9个种;归于链球菌属的有1个种;归于乳球菌属的有3个种和亚种;归于明串珠菌属的有6个种和亚种;归于片球菌属的有1个种。研究表明,内蒙古牧区乳及乳制品中乳酸菌的种类多、分布广;有些菌株对温度和pH值等环境条件的适应性强;有些菌株还有较强发酵利用松三糖、蜜二糖、棉子糖等糖的能力。     

奶牛瘤胃微生物研究进展和趋势

近年来在奶牛试验中,对瘤胃微生物的研究引起了人们越来越多的兴趣。这些研究的目的多是将微生物组成变化与日粮组成、宿主生产性能(如饲料效率,产奶量,乳脂等)、健康(如瘤胃酸中毒和亚急性酸中毒)以及环境(如甲烷排放)联系起来,另外还有一些研究则强调了微生物在多种反刍动物瘤胃发育中的作用。关于奶牛瘤胃微生物的大部分发现都是基于扩增子测序,可以揭示瘤胃微生物的分类组成,以及在不同处理条件下瘤胃菌群的变化。尽管新兴的宏基因组学和宏转录组学能够深入探索瘤胃微生物的功能,但在数据分析和解释方面也带来了更多的挑战,如目前大多数论文都严重依赖于相关性和推测分析。综述了奶牛瘤胃微生物研究的进展和局限,包括瘤胃微生物与产奶效率、甲烷排放以及瘤胃发育的关系,以及奶牛瘤胃微生物未来的研究趋势。     

Once-a-day milking of Holstein and Montbéliarde cows for 7 weeks in mid-lactation

This study aimed at comparing the effects of once-a-day (OAD) milking during the descending phase of lactation between cows from the two most common breeds in France (Holstein and Montbéliarde). This study was carried on during two successive summers on a total of 50 Holstein and 38 Montbéliarde cows. During 7 weeks, half of the cows from each breed was milked OAD while the other half was milked twice a day (TAD). The animals were also followed for the next 3 or 5 weeks when they were all milked TAD, to check for any residual effect of OAD milking. The behaviour of OAD cows was observed around milking time. The incidence of diseases, the main performance variables (milk production, milk flow rate, live weight and body condition score), the detailed composition of milk (fat, protein, lactose, somatic cells, minerals, pH, free fatty acid (FFA), nitrogen fractions and enzymes) and some technological variables (clotting time and curd firmness) were measured on all cows.Some signs of disturbance were observed in the OAD cows at the time when milking was omitted: some cows mooed, some went close to the exit of the paddock, some leaked milk prior to milking. However, these signs disappeared after 2 days. After the experimental period, the live weight and the body condition score of TAD and OAD cows did not differ significantly. OAD cows produced 4.5 kg/day less than TAD (P < 0.001), this being more marked in Holstein (5.7 kg/day, P < 0.001) than Montbéliarde (3.3 kg/day, P < 0.001) cows. The milk contents of fat, whey protein, casein, total protein and phosphorus, and its plasminogen activity, were higher with OAD cows while lactose and FFA contents, and lipoprotein lipase activity were lower, with no interaction observed with breed. During the subsequent 3 weeks, when all cows were again milked TAD, OAD cows still produced 1.7 kg/day less milk (P < 0.01) with slightly higher fat and protein content.OAD milking for 7 weeks during the descending phase of lactation decreased milk production but increased milk content of most components, with a low residual effect. Montbéliarde cows were less affected by OAD milking than Holstein cows.     

Identifying Stakeholders’ Views on the Eco‐efficiency Assessment of a Municipal Solid Waste Management System

Life cycle assessment (LCA) is one of the most popular methods of technical‐environmental assessment for informing environmental policies, as, for instance, in municipal solid waste (MSW) management. Because MSW management involves many stakeholders with possibly conflicting interests, the implementation of an LCA‐based policy can, however, be blocked or delayed. A stakeholder assessment of future scenarios helps identify conflicting interests and anticipate barriers of sustainable MSW management systems. This article presents such an approach for Swiss waste glass‐packaging disposal, currently undergoing a policy review. In an online survey, stakeholders (N = 85) were asked to assess disposal scenarios showing different LCA‐based eco‐efficiencies with respect to their desirability and probability of occurrence. Scenarios with higher eco‐efficiency than the current system are more desirable and considered more probable than those with lower eco‐efficiency. A combination of inland recycling and downcycling to foam glass (insulation material) in Switzerland is desired by all stakeholders and is more eco‐efficient than the current system. In contrast, institutions of MSW management, such as national and regional environmental protection agencies, judge a scenario in which nearly all cullet would be recycled in the only Swiss glass‐packaging factory as more desirable than supply and demand stakeholders of waste glass‐packaging. Such a scenario involves a monopsony rejected by many municipalities and scrap traders. Such an assessment procedure can provide vital information guiding the formulation of environmental policies.     

Accounting for transportation impacts in the environmental assessment of waste management plans

Background, aim, and scope  Many recent studies on waste management have described in detail the potential impacts of recycling and final treatment of municipal waste. In public debates, the attention has also been focused on the choice of final disposal technologies (e.g. landfilling vs. incineration). However, a comprehensive assessment of the impacts of waste collection and transport was still lacking. In the present study, we use LCA to evaluate the potential impact of the provincial waste management plan of Varese (northern Italy). Particular attention is devoted to the estimation of environmental impacts generated during waste transport. Materials and methods  A detailed Life Cycle Inventory was built for the transportation phase, based on primary data collected by interviewing the agencies involved in waste collection. To model the recycling and final disposal phase we relied on the BUWAL 250 database. Impacts were evaluated with the Eco-Indicator 99 method in its egalitarian formulation. Results  The results of our analysis reveal that the major potential impacts of the plan are associated with waste collection and transport. These impacts are partially compensated by reduced resource consumption through recycling and energy recovery through incineration. Discussion  The outputs of the LCIA were compared with those obtained by using other ecoindicators (Eco-Indicator 99 hierarchist and individualist, CML2, EPS2000). Although not comparable on a quantitative basis, they are qualitatively consistent. Conclusions  Neglecting the effects of collection and transport might result in a severe underestimation of the environmental impacts of a waste management system, especially as refers to depletion of fossil fuels, emission of respiratory inorganics and climate change. To reduce the environmental impact of waste management systems, an accurate optimisation of waste transport is required. Recommendations and perspectives  Effective waste management planning requires the explicit inclusion of waste collection and transport when comparing alternative management policies.     

Genome-wide association study of milk production traits in a crossbred dairy sheep population using three statistical models

Milk production is one of the most important characteristics of dairy sheep, and the identification of genes affecting milk production traits is critical to understanding the genetics and improve milk production in future generations. Three statistical techniques, namely GWAS, ridge-regression BLUP and BayesC , were used to identify SNPs in significant association with three milk production traits (milk yield, fat yield and protein yield) in a crossbred dairy sheep population. The results suggested that chromosomes 1, 3, 4, 5, 7 and 11 were likely to harbor genes important to milk production because these chromosomes had the greatest top-100-SNP variance contributions on the three milk production traits. The GWAS analysis identified between 74 and 288 genome-wide significant SNP (P < 0.05) whereas the BayesCπ model revealed between six and 63 SNPs, each with >95% posterior probability of inclusion as having a non-zero association effect on at least one of the three milk production traits. Positional candidate genes for milk production in sheep were searched, based on the sheep genomic assembly OAR version 3.1, such as those which map position coincided with or was located within 0.1 Mbp of a genome-wide suggestive or significant SNP. These identified SNPs and candidate genes supported some previous findings and also added new information about genetic markers for genetic improvement of lactation in dairy sheep, but keeping in mind that the majority of these positional candidate genes are not necessarily true causative loci for these traits and future validations are thus necessary.