Abstract The aim was to evaluate the association between growth, carcass and visual scores traits with precocious calving in Nellore cattle. Birth weight (BW), weight at 120, 210, 365 and 450 days of age, pre and post-weaning average daily gain, rib eye area, backfat thickness (BF), rump fat thickness and visual scores obtained at 18 months were used for the analysis. Records from 700 females born between 2009 and 2015, exposed to mating starting at 11 months of age were analyzed. Discriminant analyzes were performed with the software Statistica. BW and BF showed the highest (P>0.01) discrimination value for early heifer pregnancy (EP). Extreme intrauterine growth retardation can result in slower growth, which reflects in the worst reproductive performance, confirmed by the variation in BW between precocious and conventional heifers. The results also demonstrate that the level of body fat affects begin of puberty. Bone structure, musculature, depth, tail insertion and rump scores presented the highest discrimination value for EP. These traits can be used as selection tools to improve sexual precocity in female Nellore cattle. The results obtained in this study would support farmers to guide the heifer management and decisions in order to enhance the EP.

ABSTRACT Fifty-seven primiparous Angus, Hereford, and crossbred cows were used to study the effect of strategic supplementation on metabolic, productive, and reproductive responses. The experiment had two periods including four phases: prepartum supplementation (phase I; 52 days), early postpartum (phase II; 43 days), pre-mating supplementation (phase III; 21 days), and the last phase including mating, gestation, and lactation until weaning (phase IV; 103 days). Phases I and II were considered as period 1, and phases III and IV were considered as period 2. During phase I (−52±2 days before calving to birth), half of the cows received a supplement (S-), and the rest only grazed native swards (C-). For phase III (59±2 days postpartum [DPP] until mating), cows from the previous treatments (C- or S-) were sorted in two levels of pre-mating supplementation, supplemented (-S) or not supplemented (-C), resulting in four treatment combinations (CC, CS, SC, and SS). The supplement was 1 kg dry matter/cow per day of whole rice bran and 550 mL/cow per day of crude glycerin. In period 1, cows receiving prepartum supplementation increased concentration of cholesterol, glucose, and albumin and decreased concentration of non-esterified fatty acids, beta-hydroxybutyrate, and urea. This improvement in energy balance was reflected in a higher body condition score at calving. Alternatively, in period 2, pre-mating supplementation only increased cholesterol concentration. None of the supplementation periods affected the weaning weight of calves. Prepartum, but not pre-mating, supplementation increased total pregnancy rate. A short prepartum supplementation improves pregnancy rate of primiparous cows managed under extensive production systems. However, there is no additional benefit of supplementation during the pre-mating period.

Los resultados de las primeras evaluaciones del Proyecto Ovejas Prolíficas de INIA (2008-2011) muestran que la cruza Frisona Milchschaf x Corriedale o Finnish Landrace x Corriedale desteta 60 % más corderos que la Corriedale pura y, por otro lado, la cruza Finnish Landrace x Frisona Milchschaf desteta 85 % más que la Corriedale pura. Sin embargo y bajo las mismas condiciones productivas, no se conoce el comportamiento al parto y la producción de calostro de estos nuevos biotipos. Para recabar información, se realizó un experimento en INIA La Estanzuela, Colonia, Uruguay (34ºS; 57ºO) donde se utilizaron 61 borregas de 4-6 dientes nacidas en la primavera del año 2010. Se utilizaron dos razas puras: Corriedale (C.C) y Frisona Milchschaf (M.M) y las cruzas Finnish Landrace x Corriedale (F.C), Frisona Milchschaf x Corriedale (M.C), 3/4 Frisona Milchschaf - 1/4 Finnish Landrace (M.(F.M)) y 7/8 Finnish Landrace - 1/8 Corriedale (F.(FxF.C)), apareadas con carneros Texel. El incremento de sangre Finnish en la cruza redundó en un aumento en la prolificidad (2,2; 2,3 y 2,4 para 1/4; 1/2 y 7/8 Finnish) con corderos más livianos y menor asistencia al parto. Tanto la media sangre Milchschaf como la pura tuvieron una prolificidad similar e intermedia (1,8 M.C y 1,7 M.M) mientras que la asistencia al parto fue alta. La producción y composición de calostro fue similar entre biotipos a excepción de M.M que produjo más. No existió diferencia en eficiencia placentaria entre biotipos. El peso vivo al nacimiento de los corderos influyó sobre el comportamiento de los mismos en su primera hora de vida, precisamente en el tiempo desde el nacimiento hasta que lograron pararse y mamar.

The results of the first evaluation of the Prolific Sheep Project of INIA (2008-2011) demonstrated that the crossbred biotypes Corriedale by East Friesian or Corriedale by Finnish Landrace weaned 60 % more lambs than pure Corriedale and, on the other hand, the crossbred East Friesian by Finnish Landrace weaned 85 % more than pure Corriedale. However, and under the same productive conditions, the behavior at lambing and colostrum production of these new biotypes are unknown. In order to find out, an experiment was conducted at INIA La Estanzuela, Colonia, Uruguay (34ºS; 57ºO) where 61 female lambs 4-6 teeth born in the spring of 2010 were evaluated. Two pure breeds were used: Corriedale (C.C) and East Friesian (M.M), and the crosses Finnish Landrace x Corriedale (F.C), East Friesian x Corriedale (M.C), 3/4 East Friesian - 1/4 Finnish Landrace (M.(F.M)), 7/8 Finnish Landrace - 1/8 Corriedale (F.(FxF.C)), mated with Texel rams. The increase in Finnish blood resulted in more prolificacy (2.2; 2.3 and 2.4 for 1/4; 1/2 and 7/8 Finnish with lighter lambs and less lambing assistance. Both half and pure East Friesian had similar and moderate prolificacy (1.8 M.C and 1.7 M.M) whereas lambing assistance was high. Colostrum production and composition was similar between biotypes, with the exception of M.M, that produced more. There were no differences in placental efficiency between biotypes. Birth weight of lambs affected their behavior in the first hour of life, specifically the time from birth to first stand up to suckle.

Las primeras evaluaciones del Proyecto Ovejas Prolíficas del Instituto Nacional de Investigación Agropecuaria (INIA, 2008-2011) muestran que las madres cruza Frisona Milchschaf x Corriedale y Finnish Landrace x Corriedale destetan 60 % más corderos que la madre Corriedale pura, mientras que la madre cruza Finnish Landrace x Frisona Milchschaf desteta 85 % más que la madre Corriedale pura. Para recabar información respecto a la edad con que se inicia la pubertad, la estación de cría y tasa ovulatoria de estos nuevos biotipos se realizó un experimento con 87 corderas nacidas en la primavera 2010. Se utilizaron dos razas puras: Corriedale (C.C) y Frisona Milchschaf (M.M) y las siguientes cruzas: Finnish Landrace x Corriedale (F.C), Frisona Milchschaf x Corriedale (M.C), ³/4 Frisona Milchschaf - ¹/4 Finnish Landrace (M.(F.M)), 7/8 Finnish Landrace -¹/8 Corriedale (F.(FxF.C)). Las corderas con más de 75 % de sangre Frisona Milchschaf (M.M y M.(F.M)) presentaron los mayores porcentajes de inicio de pubertad en su primer año de vida (>90 %). La estación de cría de estos dos biotipos fue la más amplia con una tasa ovulatoria de 1,0. Las corderas F.(FxF.C) siguieron a las anteriores en el porcentaje que alcanzó la pubertad y en la amplitud de la estacionalidad con una tasa ovulatoria 1,5. La estación de cría como borregas fue similar para todos los biotipos destacándose la alta tasa ovulatoria de las cruzas Finn (1,9-2,8) seguidas de Frisona Milchschaf (1,5-1,8) y de Corriedale (1.3).

First evaluations of the Prolific Sheep Project of Instituto Nacional de Investigación Agropecuaria (INIA, 2008-2011) demonstrated that the crossbred mothers Corriedale by East Frisian or Corriedale by Finnish Landrace weaned 60 % more lambs than pure Corriedale, and the crossbred mothers East Friesian by Finnish Landrace weaned 85 % more than pure Corriedale. To obtain information regarding the age when puberty begins, the breeding season, and the ovulation rate of these new biotypes, an experiment was carried out with 87 female lambs born the Spring of 2010. Two pure breeds: Corriedale (C.C) and East Friesian (M.M) and the following crosses: Finnish Landrace x Corriedale (F.C), East Friesian x Corriedale (M.C), ¾ East Friesian - ¼ Finnish Landrace (M.(F.M)), 7/8 Finnish Landrace -¹/8 Corriedale (F.(FxF.C)) were used. Female lambs with more than 75 % of East Friesian blood (M.M and M.(F.M)) had the highests percentages of puberty onset in their first year of life (> 90 %). Their breeding season was the widest with an average ovulation rate of 1.0. F.(FxF.C) lambs followed the previous ones in the percentage reaching puberty and the width of the breeding season with an average ovulation rate of 1.5. Breeding season of hoggets was similar for all biotypes, however, hoggets with Finn blood were outstanding by their high ovulation rate (1.9-2.8) followed by East Friesian (1.5-1.8) and Corriedale (1.3).