Longevity is a key determinant of economic efficiency and sustainability in dairy cattle production. The study evaluated longevity and lifetime productivity traits in Red breed (RB) and Holstein breed (HB) dairy cows in Latvia and assessed the effects of birth year, age at first calving (AFC), and farm size. Data from 279,818 culled and living cows born between 2010 and 2019 were analyzed. The aim of the study was to investigate biological and farm-level factors affecting dairy cow longevity in RB and HB populations. RB and HB cows born between 2010 and 2013 had significantly longer (p< 0.05) total lifespan (LS) and productive life (PL) than cows born in later years; however, they showed lower life day (MPD) and productive life day (MPPD) milk productivity. AFC significantly affected MPD and MPPD. The highest life-day productivity in RB cows was observed at AFC of 22.1 – 24 months, while in HB cows it was observed at < 24 months. Significantly longer LS and PL were recorded on farms with fewer than 20 cows, whereas the highest MPD was observed on farms with 101 – 500 cows in RB breed and 101 – 200 cows in HB.

Conservation programmes for two local dairy cattle breeds—Latvian Brown old type (BV) and Latvian Blue (LZ)—commenced in 2004. The aim of this study was to evaluate genetic diversity in the BV and LZ local cattle populations using SNP data. This study was based on genotype data from 96 BV and 75 LZ cows and 20 BV and 18 LZ bulls. The SNPs were determined using the GGP 100K bovine SNP BeadChip. Quality control (QC) and genotype data analysis were performed using PLINK v1.9. The observed heterozygosity was moderate, at around 0.4, for both breeds. Inbreeding coefficients were estimated based on homozygosity runs (F_ROH) to compare recent and ancient inbreeding in the BV and LZ populations. Therefore, the ROH segments were divided into segments with the four classes (1–4 Mb, 4–8 Mb, 8–16 Mb, and above 16 Mb). Shorter ROH regions (ROH < 4 Mb) predominated in the genome. ROH regions with lengths above 16 Mb covers 4–6% of the genome in BV and 11% in LZ population. The average inbreeding coefficient for approximately three generations (F_ROH>16) was 2.30% and 4.87% for BV and LZ cows (p < 0.05), respectively, and 2.59% and 3.85% for BV and LZ bulls, respectively. This study demonstrates that inbreeding has increased from generation to generation (F_ROH>16 is higher compared with F_ROH<16) in both populations. The level of current inbreeding in LZ is higher compared with that in the BV breed. The overall level of inbreeding in the BV and LZ populations is low, but there is a high level of inbreeding among a few animals. The impact of inbreeding on cow productivity has been observed in the LZ and BV cow populations. As a result, breeding organisations need to monitor and control the level of inbreeding and prevent the loss of genetic diversity in these animal populations. Breeders should minimize mating among close relatives; introduce genetically unrelated animals, use pedigree, and genomic information in controlling rates of inbreeding.

Longevity is a key determinant of economic efficiency and sustainability in dairy cattle production. The study evaluated longevity and lifetime productivity traits in red breed (RB) and Holstein breed (HB) dairy cows in Latvia and assessed the effects of birth year, age at first calving (AFC), and farm size. Data from 279,818 culled and living cows born between 2010 and 2019 were analyzed. The aim of the study was to investigate biological and farm-level factors affecting dairy cow longevity in RB and HB populations. RB and HB cows born between 2010 and 2013 had significantly longer (p < 0.05) total lifespan (LS) and productive life (PL) than cows born in later years; however, they showed lower life day (MPD) and productive life day (MPPD) milk productivity. AFC significantly affected MPD and MPPD. The highest life day productivity in RB cows was observed at AFC of 22.1–24 months, while in HB cows it was observed at <24 months. Significantly longer LS and PL were recorded on farms with fewer than 20 cows, whereas the highest MPD was observed on farms with 101–500 cows in RB and 101–200 cows in HB.