Linear or nonlinear genetic relationships between productive life and functional productive life at 72 mo, with final score (SCO), stature, strength, dairyness (DAI), teat diameter, rear legs (side view), rump angle, rump width (RUW), fore udder attachment (FUA), rear udder height, rear udder arch, udder depth (UDD), suspensory ligament (SUS), and teat placement, as well as heritabilities and correlations were estimated from multibreed US dairy goat records. Productive life was defined as the total days in production until 72 mo of age (PL72) for goats having the opportunity to express the trait. Functional productive life (FPL72) was analyzed by incorporating first lactation milk yield, fat yield, protein yield, and SCO in the statistical model. Heritabilities and correlations were estimated using linear mixed models with pedigree additive genetic relationships and ASReml software. Nonlinearity of genetic relationships was assessed based on second-degree polynomial (quadratic) regression models, with the breeding values of PL72 or FPL72 as responses and the breeding values for each type trait (linear and quadratic) as predictor variables. Heritability estimates were 0.19, 0.14, 0.18, 0.20, 0.14, 0.07, 0.28, 0.20, 0.15, 0.13, 0.25, 0.18, 0.20, 0.21, 0.21, and 0.32 for PL72, FPL72, SCO, stature, strength, DAI, teat diameter, rear legs, rump angle, RUW, FUA, rear udder height, rear udder arch, UDD, SUS, and teat placement, respectively. The type traits SCO, RUW, and FUA were the most correlated with PL72 and FPL72, so these may be used as selection criteria to increase longevity in dairy goats. An increase in the coefficient of determination >1% for the second degree, compared with that for the linear model for either PL72 or FPL72, was taken as evidence of a nonlinear genetic relationship. Using this criterion, PL72 showed maximum values at intermediate scores in DAI, UDD, and RUW, and maximum values at extreme scores in FUA and SUS, whereas FPL72 showed maximum values at intermediate scores in DAI and UDD, and maximum values at extreme scores in FUA, RUW, and SUS. Selecting for increased SCO, RUW, and FUA will lead to an increase of FPL72 in goats. Consideration of nonlinear relationships between DAI, FUA, RUW, SUS, and UDD may help in the design of more efficient breeding programs for dairy goats using conformation traits.

Heritabilities and correlations for milk yield (MY), fat yield (FY), protein yield (PY), combined fat and protein yield (FPY), fat percentage (F%), protein percentage (P%), age at first kidding (AFK), interval between the first and second kidding (KI), and real and functional productive life at 72mo (FPL72) of 33,725 US dairy goats, were estimated using animal models. Productive life was defined as the total days in production until 72mo of age (PL72) for goats having the opportunity to express the trait. Functional productive life was obtained by correcting PL72 for MY, FY, PY, and final type score (FS). Six selection indexes were used, including or excluding PL72, with 6 groups of different economic weights, to estimate the responses to selection considering MY, FY, PY, and PL72 as selection criteria. The main criteria that determined the culling of a goat from the herd were low FS, MY, and FY per lactation. Heritability estimates were 0.22, 0.17, 0.37, 0.37, 0.38, 0.39, 0.54, 0.64, 0.09, and 0.16 for PL72, FPL72, MY, FY, PY, FPY, F%, P%, KI, and AFK, respectively. Most genetic correlations between the evaluated traits and PL72 or FPL72 were positive, except for F% (-0.04 and -0.06, respectively), P% (-0.002 and -0.03, respectively), and AFK (-0.03 and -0.01, respectively). The highest genetic correlations were between FPL72 and MY (0.39) and between PL72 and MY (0.33). Most phenotypic correlations between the traits evaluated and FPL72 and PL72 were positive (>0.23 and >0.26, respectively), except for F% (-0.004 and -0.02, respectively), P% (-0.05 and -0.02), KI (-0.01 and -0.07), and AFK (-0.08 and -0.08). The direct selection for PL72 increased it by 102.28d per generation. The use of MY, FY, PY, KI, or AFK as selection criteria increased PL72 by 39.21, 27.33, 35.90, -8.28, or 2.77d per generation, respectively. The inclusion of PL72 as selection criterion increased the expected response per generation from 0.15 to 17.35% in all selection indices studied.

Aim:The aim of this study was to estimate the heritability, genetic and phenotypic correlations, and the genetic trends for pre-weaning growth traits including the birth weight (BWT), weaning weight (WWT), pre-weaning daily gain (PWDG), and weaning age (WA) in Awassi lambs.Materials and Methods:A total of 5131 Awassi lambs from two Jordanian sheep breeding stations were used. A multitrait animal model and restricted maximum likelihood methods were used to estimate the covariances between the studied traits.Results:The mean±standard deviation of BWT, WWT, PWDG, and WA was 4.48±0.8 kg, 17.13±0.7 kg, 0.2±0.07 g, and 65.5±0.7 days, respectively. Heritability estimates were 0.30±0.04 for BWT, 0.19±0.04 for WWT and PWDG, and 0.2±0.04 for WA. Positive genetic correlations were obtained between BWT and other traits, while negative correlations were obtained between WWT, PWDG, and WA (−0.50±0.12) and between WWT and WA (−0.67±0.14). The positive phenotypic correlation was obtained between WA and PWDG (0.63±0.01). The highest additive genetic variance was obtained for WA (34.58), while the lowest was estimated for PWDG (6.22E-04). The highest phenotypic variance was obtained for WA (175.5), while the lowest value obtained was for BWT (0.54). Maternal additive variance ranged between 0.13 and 0.03. The genetic trends were around zero for all studied traits.Conclusion:Selection should be conducted using animals with high estimated breeding values through controlled breeding.

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This study aimed to evaluate the dietary effect of the thiamine diphosphate (TD) glycogenic cofactor on the productive performance of male (M) and ewe (E) lambs exposed to outdoor conditions natural conditions of high summer temperatures in an arid region. Twenty 4month-old Dorper x Katahdin sheep were used, which were assigned to the following treatment combinations (n=5) according to a 2 2 -factorial arrangement under a randomized complete block design: 1) M without TD, 2) M with TD, 3) H without TD and 4) H with TD. No productive performance variable was affected (P>0.05) by the interaction or the DT main effect. M-lambs had higher (P>0.05) growth rate, feed intake and final weight than E-lambs. It is concluded that, regardless of the sex, DT does not improve productive performance of feedlot hair sheep under heat stress.