Database of average values of parameters of sire rams of Latvian dark-head breed calculated from values of intensive fattening lambs within the framework of the project of the Latvian Council of Science LZP-2021/1-0489 project

Project of The Latvian Council of Science (LCS) - LZP-2021/1-0489 project: “Development of an innovative approach to identify biological determinants involved in the between-animal variation in feed efficiency in sheep farming.”

The aim of the project is to determine whether the feed efficiency status of Latvian meat sheep breeds could be predicted using a panel of genetic and molecular markers previously found to be associated with divergent Feed efficiency status in a training population of lambs when fed the same diet.

Novelty: to determine the parameters predicting the most productive result of lamb rearing, we set out to develop the cheapest and most effective method for determining markers of feed efficiency - based on molecular and genetic markers obtained from the blood of live lambs.

About the project:

The costs associated with lambing (buying or keeping sheep) and preparing or purchasing feed are the two largest components of variable costs in sheep raising. Feed costs are high due to poor grain growing conditions in major producing countries, the use of feed grains in ethanol production, and increased competition for land in crop production compared to urban development. Feed efficiency in growing lambs (i.e., the animal's ability to reach a market or adult body weight (BW) with the least amount of feed intake), is a key factor in the sheep industry. Improving Feed efficiency reduces production costs. Improving Feed efficiency by 5% can bring economic benefits that are up to four times higher than a 5% increase in average daily gain (ADG).

Traditionally, meat breeding programs have focused on outputs due mainly to the routine availability of phenotypic data on outputs or correlated traits. Currently, no marker has successfully explained enough of the variability in feed efficiency that they were used as part of a routine improvement program, as well as according to our data, no genetic parameters for performance and feed efficiency traits are available for sheep. The physiological determinants of feed efficiency or putative biomarkers used to analyze animal-to-animal variation in live lambs could be used as a cost-effective and rapid tool for genetic selection or management decisions.

As of 2018, there were 49.5 thousand ewes and 73 sire rams in Latvia from a flock of 134.29K sheep. In 2018, Latvian Dark-Head (Latvijas tumšgalve; LT) sheep were bred to implement the sheep breeding program in 35 farms, which had a total of 3,752 ewes, while 13 farms had 43 breeding rams. According to the EUROSTAT data, the number of sheep in Latvia in 2018 was 107.29K, but in December 2021 was 90.34K.

The Latvian Dark-Head sheep breed was created by crossing local Latvian sheep with Shropshire and Oxfordshire rams imported from Sweden and England. The first pedigree or breeder's book for LT rams was issued in 1939. Currently, the live weight of ewes of the Latvian Dark-Head breed is about 55 – 65 kg, rams - 95 – 120 kg, wool cut 3.5 – 4.5 and 5.0 – 6.0 kg, respectively. The average prolificacy of ewes is 150 - 160%.

Breeding of Latvian Dark-Head sheep in Latvia is carried out according to phenotypic and bloodline data, without information about values of feed efficiency indicators or carrying out genetic breeding. Therefore, this study aimed to analyze the Latvian Dark-Head breeds rams according to lambs' feed efficiency values.

About the data of the project:

LZP-2021/1-0489 project data on Latvian dark-head (LT; Latvijas tumšgalve) of the year 2022 lamb samples, or A22_LT group. In the group were 48 lambs from 13 sire rams.

Based on the requirements of the breeding program of the breeds, every year, the offspring of the sire ram, certified for breeding activity, are selected and analyzed to estimate the sire rams. All lambs were born as twins, triplets or quadruplets from different ewes and health status was assessed prior to inclusion in the study so that there were at least two lambs per sire ram from the breed. This study was carried out in cooperation with Latvian Sheep Breeders' Association at the ram breeding control station.

The dataset includes average data of each sire ram: (1) ultrasonography measurements of lambs during the beginning and end of fattening, (2) intensive fattening data - real and calculated on the 90th and 150th day, (3) the amount of feed used, (4) slaughter data, (5) biochemical indicators: Insulin-like growth factor 1, Insulin, Total thyroxine, Adrenocorticotropic hormone, Haematocrit, Hemoglobin, Glucose, (6) feed efficiency indicators: Feed efficiency (FE), Feed conversion ratio (FCR), Relative growth rate (RGR), Kleiber’s ratio (KR), Residual feed intake (RFI), Residual weight gain (RWG) and Residual intake and body weight gain (RIG).

The data is the joint property of the participants of the LCS project: the University of Latvia and the Latvian University of Life Sciences and Technologies.

拉脱维亚科学委员会（Latvian Council of Science, LCS）LZP-2021/1-0489号项目："绵羊养殖中饲料效率个体间差异相关生物学决定因子的创新性鉴定方法开发"

本项目旨在探究：针对饲喂相同日粮的羔羊训练群体中，已被证实与饲料效率分化表型相关的遗传与分子标记面板，能否用于预测拉脱维亚肉用绵羊品种的饲料效率状态。

本项目创新点：为确定预测羔羊育肥最优生产性能的参数，我们拟开发一套基于活体羔羊血液提取的分子与遗传标记的、兼具低成本与高效性的饲料效率标记鉴定方法。

项目背景：
绵羊养殖的可变成本主要由两项构成：羔羊繁育（购羊或养羊）与饲料制备或采购成本。由于主产国谷物种植条件不佳、乙醇生产使用饲料谷物，以及作物生产用地竞争日益激烈（相较于城市开发），饲料成本居高不下。生长羔羊的饲料效率（即动物以最少采食量达到商品体重或成年体重的能力）是绵羊产业的核心影响因素。提升饲料效率可降低生产成本：饲料效率每提升5%带来的经济效益，最高可达平均日增重（average daily gain, ADG）提升5%的四倍。

传统肉羊育种项目主要聚焦于产出性状，这主要是因为产出性状或相关性状的表型数据可常规获取。截至目前，尚无足够有效解释饲料效率变异的标记可应用于常规育种改良项目；且据我们所知，目前尚无针对绵羊生产性能与饲料效率性状的遗传参数公开数据。可用于分析活体羔羊个体间饲料效率差异的生理学决定因子或推定生物标志物，有望成为用于遗传选育或管理决策的低成本、快速检测工具。

截至2018年，拉脱维亚绵羊存栏量为13.429万只，其中母羊4.95万只、种公羊73只。2018年，拉脱维亚黑头羊（Latvijas tumšgalve; LT）的育种项目在35个农场开展，共涉及3752只母羊，其中13个农场饲养有43只育种用公羊。据欧盟统计局（EUROSTAT）数据，2018年拉脱维亚绵羊存栏量为10.729万只，2021年12月降至9.034万只。

拉脱维亚黑头羊品种是通过将本地拉脱维亚绵羊与从瑞典、英国引进的萨福克（Shropshire）和牛津（Oxfordshire）公羊杂交培育而成。首个黑头羊公羊血统登记册（育种手册）于1939年发布。目前，拉脱维亚黑头羊母羊活重约55~65kg，公羊活重95~120kg，剪毛量分别为3.5~4.5kg和5.0~6.0kg。母羊平均产羔率为150%~160%。

拉脱维亚目前的黑头羊育种仅基于表型与血统数据，未涉及饲料效率指标的测定或遗传育种相关工作。因此，本研究旨在基于羔羊的饲料效率值，对拉脱维亚黑头羊的种公羊进行分析评估。

项目数据说明：
LZP-2021/1-0489项目包含2022年拉脱维亚黑头羊（LT; Latvijas tumšgalve）羔羊样本数据，对应A22_LT组。该组包含来自13只种公羊的48只羔羊。

根据该品种育种项目的要求，每年都会选择经育种资质认证的种公羊的后代进行分析，以评估种公羊的性能。所有羔羊均为双羔、三羔或四羔，来自不同母羊；且在纳入本研究前已评估健康状况，确保每只种公羊至少有2只羔羊参与试验。本研究与拉脱维亚绵羊育种者协会合作，在种公羊育种管控站开展。

本数据集包含每只种公羊的平均数据：(1) 育肥期初与期末的羔羊超声检测指标；(2) 强度育肥相关数据——第90天与第150天的实测与计算数据；(3) 饲料使用量；(4) 屠宰数据；(5) 生化指标：胰岛素样生长因子1、胰岛素、总甲状腺素、促肾上腺皮质激素、红细胞比容、血红蛋白、葡萄糖；(6) 饲料效率指标：饲料效率（Feed Efficiency, FE）、饲料转化率（Feed Conversion Ratio, FCR）、相对生长率（Relative Growth Rate, RGR）、克莱伯比率（Kleiber’s ratio, KR）、剩余采食量（Residual Feed Intake, RFI）、剩余增重（Residual Weight Gain, RWG）以及剩余采食量与增重（Residual Intake and Body Weight Gain, RIG）。

本数据为拉脱维亚科学委员会项目参与方——拉脱维亚大学与拉脱维亚生命科学与技术大学的共同财产。