Genomic diversity and breed composition of Vietnamese smallholder dairy cows

Abstract

Vietnamese smallholder dairy cows (VDC) are the result of crossbreeding between different zebu (ZEB) and taurine dairy breeds through many undefined generations. Thus, the predominant breed composition of VDC is currently unknown. This study aimed to evaluate the level of genetic diversity and breed composition of VDC. The SNP data of 344 animals from 32 farms located across four dairy regions of Vietnam were collected and merged with genomic reference data, which included three ZEB breeds: Red Sindhi, Sahiwal and Brahman, three taurine breeds: Holstein (HOL), Jersey (JER) and Brown Swiss (BSW), and a composite breed: Chinese Yellow cattle. Diversity and admixture analyses were applied to the merged data set. The VDC were not excessively inbred, as indicated by very low inbreeding coefficients (Wright's F IS ranged from −0.017 to 0.003). The genetic fractions in the test herds suggested that the VDC are primarily composed of HOL (85.0%); however, JER (6.0%), BSW 5.3%) and ZEB (4.5%) had also contributed. Furthermore, major genotype groupings in the test herds were pure HOL (48%), B3:15/16HOL_1/16ZEB (22%) and B2:7/8HOL_1/8ZEB (12%). The genetic makeup of the VDC is mainly components of various dairy breeds but also has a small percentage of ZEB; thus, the VDC could be a good genetic base for selecting high milk-producing cows with some degree of adaptation to tropical conditions.

Multivariate analysis identifying the main factors associated with cow productivity and welfare in tropical smallholder dairy farms in Vietnam

“…Secondly, nutrition; these were variables 8 to 23, from a nutrition study (Bang et al, 2021a ). Thirdly, animal; these were variables 24 to 41, from a cow welfare and productivity study (Bang et al, 2021b ) and a cow genetic study (Bang et al, 2021d ). The animal variables were grouped into three subgroups, including genetic (variables 24 to 27), physiological stage (variables 28 and 29), and productivity and welfare (variables 30 to 41).…”

“… A Body condition score: 1 = thin to 5 = obese; Panting score: 0 = normal to 4.5 = extreme heat stressed Variables 1 to 7 were from a housing management study (Bang et al, 2021c ), 8 to 23 from a nutrition study (Bang et al, 2021a ), 24 to 27 from a cow genetic study (Bang et al, 2021d ), and 28 to 41 from a cow welfare and productivity study (Bang et al, 2021b ) …”

“…In this study, we focused on the multidimensionality of Vietnamese SDFs. The aim was to combine the data from the different themes of previous studies by the same authors (Bang et al, 2021b , 2021a , 2021c , 2021d ) to build multivariate explanatory models to enable the identification and ranking of potential factors affecting the productivity and welfare of dairy cows in SDFs. The factors include milk yield and quality, body weight and body condition score, heat stress level, fertility, and udder health of the cows.…”

Effects of dietary seaweed supplementation on milk productivity, milk quality and health of dairy cows

“…In tropical developing countries, dairy production systems are affected by many factors (Chu et al, 2004;Nguyen et al, 2016) including genetics, nutrition, infectious, parasitic diseases, or heat stress caused by high temperature and humidity. The development of dairy production in Vietnam requires the enhancement of knowledge and skills of farmers (Nguyen, 2021) related the general husbandry such as genetics (Bang et al, 2021c), nutrition (Nguyen & Diep, 2020b;Bang et al, 2021a), and heat stress (Bang et al, 2021b) management. In addition to the primary step from breed selection for improvement of milk productivity and feed efficiency, nutritional factors also affect milk yield and compositions (Hristov et al, 2004;Lee et al, 2014;Olika, 2021), so nutrient balance plays an important role in dairy production.…”