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Abstract: The aim of this study was to identify traits of socio-economic relevance for intensive and semi-intensive dairy goat production system, to derive economic weights for the breeding goals and to propose selection indices whose criteria are easily collected by dairy goat breeders. The economic value of each trait was calculated as the difference between the average profit before and after the improvement of criteria, after increasing each trait by 1%, keeping the average of other traits unchanged. Eight selection indices were proposed. Four indices (I–IV) were determined for the intensive system and four (V–VIII) for the semi-intensive system. The traits included in each index were: milk production (MP) and lactation length (LL) (I and V); MP, LL, and age at first kidding (AFC) (II and VI); MP, LL, AFC and kidding interval (CI) (III and VII); and MP, LL, AFC, CI, somatic cell count (SCC) and total solids (TS) (IV and VIII). The average profit of the semi-intensive system was higher than the intensive system, R$ 0.18 and R$ 0.14, respectively. The use of indices III and VI promoted simultaneous improvement in both productive and reproductive traits. With differential payment for better quality milk, TS and SCC levels, use of indices IV and VIII are indicated. The choice and use of these indices depend on the definition of objectives and of the measurement ease of selection criteria. [Copyright &y& Elsevier]

• Four different networks among tick infestation, B. bovis infection level, weight gain from birth to weaning, and weight gain from weaning to yearling were compared. • There is a potential causal relationship between tick count and weight gain from birth to weaning. • There is a negative causal effect of pre-weaning gain on post-weaning gain. Tick infestation and associated diseases (i.e., babesiosis) constitute major drawbacks for improvement of beef cattle productivity in the tropics, mainly when purebred and crossbred taurine animals are used. Host-parasite-pathogen interactions form complex biological systems that are poorly understood and which significantly affect production and quality traits in ways yet to be dissected and described. This research was carried out to investigate potential causal relationships, through the use of structural equation modeling (SEM), among tick counts (TC), Babesia bovis infection level (IB) and the gains in weight: from birth to adjusted weaning age (WG), and from weaning to yearling (YG). Statistical analyses were conducted in three steps: 1) Partition of (co)variances into genetic and residual components using Bayesian multiple-trait modeling (MTM); of 2) Search for plausible causal structures by applying the inductive causation (IC) algorithm to the residual (co)variances obtained in the first step; and 3) Final analysis using SEM, which was based on the causal network learned from the IC algorithm. The most plausible results comprised three direct links between traits: WG→YG, TC→WG, and WG→IB with structural coefficients posterior means equal to -0.3026, 6.3620, and 0.0004, respectively. The final inferred directed acyclic graph (DAG) suggests that interventions on TC would directly affect WG, which would then affected YG; moreover, WG could also present a small positive effect on IB. [ABSTRACT FROM AUTHOR]

This study aimed to estimate genetic parameters for feeding behavior (FB) traits and to assess their genetic relationship with performance traits in group-housed broilers. In total, 99,472,151 visits were recorded for 95,711 birds between 2017 and 2022 using electronic feeders. The visits were first clustered into 2,667,617 daily observations for ten FB traits: daily feed intake (DFI), daily number of visits (NVIS), time spent at the feeders (TSF), number of visited feeders (NVF), visiting activity interval (VAI), feeding rate (FR), daily number of meals (NMEAL), average intake per meal (INTMEAL), number of visits per meal (VISMEAL) and interval between meals (MEALIVL). All FB traits were then considered as the average per bird across the feeding test period. Three growth traits (body weight at the start – SBW and at the end of the feeding test – FBW, and weight gain over the test period – BWG), and 2 feed efficiency (FE) traits (Feed Conversion Rate - FCR and Residual Feed Intake - RFI) were also recorded. The (co)variance components were estimated using multitrait animal mixed models. For growth and FE, the heritability (h2) estimates were moderate, ranging from 0.20 ± 0.01 (BWG) to 0.32 ± 0.02 (RFI). Overall, the h2 estimates for FB traits were higher than for productive traits, ranging from 0.31 ± 0.01 (DFI) to 0.56 ± 0.02 (TSF). DFI presented high genetic correlations (0.53–0.86) with all performance traits. Conversely, the remaining FB traits presented null to moderate genetic correlations with these traits, ranging from –0.38 to 0.42 for growth traits and between –0.14 and 0.25 for FE traits. Genetic selection for favorable feeding behavior is expected to exhibit a fast genetic response. The results suggest that it is possible to consider different feeding strategies without compromising the genetic progress of FE. Conversely, breeding strategies prioritizing a higher bird activity might result in lighter broiler lines in the long term, given the negative genetic correlations between visit-related traits (NV, NVF, and NMEAL) and growth traits (SBW and FBW). [ABSTRACT FROM AUTHOR]

Highlights • Reproductive traits showed a low correlation with carcass traits. • The results of this study are encouraging for using the probability of precocious calving as selection criteria in Nelore breed. • Selection to increase growth should increase carcass yield and scrotal circumference. • The inclusion of subcutaneous backfat or rump fat thickness in selection indexes would increase the carcass grade. Abstract This study was carried out to estimate the heritability and genetic correlations between adjusted weights at 210 (W210) and 450 (W450) days of age, scrotal circumference adjusted at 365 (SC365) and 450 (SC450) days of age, age at first calving (AFC), probability of precocious calving (PPC), stayability (STAY), ribeye area (REA), subcutaneous backfat thickness (BF), and rump fat (RF) traits. The covariance components and genetic parameters for all traits but PPC and STAY were estimated considering a linear animal model, for the remaining traits a threshold animal model was used. The single-step genomic BLUP (ssGBLUP) procedure was used for all traits, and the correlation estimates were obtained by two-traits analysis. The heritability estimated by single-trait analysis were 0.21 ± 0.01, 0.43 ± 0.01, 0.47 ± 0.02, 0.52 ± 0.02, 0.11 ± 0.01, 0.12 (0.07–0.16), 0.37 (0.26–0.38), 0.33 ± 0.02, 0.17 ± 0.01 and 0.33 ± 0.02 for W210, W450, SC365, SC450, AFC, PPC, STAY, REA, BF and RF, respectively. Growth traits (W210 and W450) showed high (0.95) genetic correlation with one another, moderate (0.30 to 0.66) with REA and scrotal circumferences, and low (−0.07 to 0.20) with female reproductive traits (AFC, PPC, and STAY) and fat carcass indicator traits (BF and RF). Female reproductive traits displayed moderate (−0.29 to 0.52) genetic correlations with male reproductive traits, and varied from low to moderate (−0.02 to 0.35) with carcass traits. Additionally, carcass traits exhibited low to moderate (−0.02 to 0.48) genetic correlations with all traits, except for the genetic correlation between BF and RF (0.73). Hence, higher genetic gains by direct selection would be obtained for W450, SC365, SC450, STAY, REA, and RF. Selection to increase growth traits might increase carcass yield and scrotal circumference, and it would not affect carcass fat content, precocity, and cow longevity indicator traits. The results of this study encourage the use of PPC in Nelore cattle since the selection for such trait would improve the productivity and longevity of the cows. The inclusion of carcass quality indicator traits such as BF or RF in selection indices would increase the genetic gain for carcass grade, but it will require further studies to estimate the economic value of these traits. [ABSTRACT FROM AUTHOR]