Browsing by Autor "Luis Camaripano"

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Genetic Parameter Estimation for Pregnancy Loss and Their Association With Reproductive and Growth Traits in Brahman Cattle Under Extensive Tropical Conditions
(Wiley, 2025) Daniel Cardona‐Cifuentes; Lúcia Galvão de Albuquerque; Milagros Arias; Sindy Liliana Caivio Nasner; Luis Camaripano; Luis Gabriel González Herrera; Patrícia Iana Schmidt; Fernando Baldi
This study estimated genetic parameters for pregnancy loss (PL) in Brahman cattle and evaluated the genetic correlation of PL with growth and reproductive traits using both the pedigree relationship matrix (A) and pedigree plus genomic relationship matrix (H). Data were collected from two herds in Bolivia, focusing on three age groups: heifers, primiparous and multiparous cows. Threshold animal models were fitted to each group. Multitrait models were fitted between the PL at different age group and between PL and the following traits: adjusted weights at 450 (W450) and 550 (W550) days, scrotal circumference adjusted at 450 (SC450) and 550 (SC550) days, accumulated cow productivity (ACP), age at first calving (AFC) and stayability (STAY). The H matrix increased the heritability for PL in heifers from 0.06 to 0.11. The genetic correlation between PL in heifers and primiparous cows changed using H (from 0.18 to 0.7), and it was high between heifers and multiparous cows. Moderate-high negative genetic correlation was observed between PL and STAY, with changes in heifers when using H (-0.17 to -0.57). AFC and PL presented medium-high positive genetic correlations. Negative correlations between PL and SC450 or SC550 were found in primiparous and multiparous cows. Using H, the correlation between PL in heifers and ACP shifted from 0.08 to -0.31, showing medium-high negative correlations for the other two age groups. Genetic correlations were low between PL and W450 or W550. Genomic information allows the use of PL as a selection criterion in heifers. Selection for major sexual precocity, longevity and productivity would enable the reduction of pregnancy loss.
Genomic study for pregnancy loss in Brahman cattle
(Oxford University Press, 2025) Sabrina Thaise Amorim; Nedenia Bonvino Stafuzza; Dina Cifuentes; J.G.N. Moraes; Bárbara Roqueto dos Reis; Richard A. Messmann; Luis Camaripano; Fernando Baldi
Reproduction has major influence on productivity of beef cattle operations. Maintaining an animal in the herd for an extended period without producing a marketable product can result in significant economic losses, compromising the efficiency of the production system. Understanding genetic variation's role in pregnancy loss (PL) is crucial for improving reproductive success in cattle. Identifying genomic regions that influence embryo and fetal survival, as well as pinpointing candidate genes associated with PL, can enhance breeding strategies. The objective of this study was to estimate variance components and investigate genetic factors associated with PL in Brahman cattle. Phenotypic records consisted of 29,905 pregnancy (28,691) and abortion (1,214) records from nulliparous, primiparous, and multiparous cows. A total of 921 animals were genotyped using a medium-density SNP chip (∼52K markers). Variance components were estimated using a threshold model to assess the binary response to PL through a single-step genomic BLUP procedure. The heritability estimate for PL was low (0.11), but the presence of genetic variance suggests that selection for improved reproductive performance is feasible. Genome-wide association analyses identified 17 candidate regions containing 92 genes. Regions on BTA4, 7, 8, 9, 11, 12, 16, 18, 19, 21, 22, and 29 harbored genes associated with embryonic development and implantation, fertilization, G protein-coupled receptors, embryonic brain development, olfactory receptor activity, and calcium signaling. Orthologous genes were also identified in humans (Homo sapiens), rats (Rattus norvegicus), and mice (Mus musculus). The candidate regions reported in this study provide insights for identifying and selecting animals with improved reproductive performance, ultimately enhancing the productivity of Brahman cattle. Moreover, our findings contribute to a better understanding of the genetic and physiological mechanisms underlying pregnancy retention in beef cattle.