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The effect of measure number of milk production (MP) on the estimation of parameters in typical and extended lactations curve parameters of local goats was evaluated. This study was conducted with 14 producers in 5 communities of the Comarca Lagunera, State of Coahuila, México. MP was measured monthly by hand-milking during 4 years. Data analyzed included 12,097 observations belonging to 2,229 lactations from 1,125 local goats. The Wood model was utilized to characterize the lactation curve and its parameters (a, b, and c). Two groups were formed, G1 (typical lactation with 3-7 milk measures), and G2 (extended lactations with 8-10 milk measures). The criterion utilized to determine the adequate number of MP measures during lactation was the standard error of the estimate. The best fit in the estimation of the curve parameters was obtained in G2. Factors affecting the curve parameters were also evaluated utilizing the MIXED procedure of SAS. Community, year, and parity number influenced all the parameters in both groups. Flock within community influenced b and c in G1. Season of parity influenced c in G2. It is concluded that a higher measure number of MP in an extended lactation helps in better estimation of lactation curve parameters.

Objective: To estimate the lactation curve and milk production of Pelibuey ewes and their relationship with preweaning growth rate of the lambs. Design/Methodology/Approach: Forty-five Pelibuey ewes were milked during 70 days in Montecillo, Mexico, in 2018, to estimate the daily and total milk production. The lactation curve was fitted with the incomplete gamma function. In addition, the effects of type of birth and ewe weight at milking on milk production were analyzed, and correlations were calculated between ewe milk production and growth rate of the lambs, per week and for the entire lactation. Results: A “typical” lactation curve was found, average ewe milk production for the whole lactation, weighted for the number of lambs suckling, was 1318 L, with 44424 g d1. Ewe weight at milking had an effect (p0.01) on milk production. Positive correlations were found (p0.05) between ewe milk production and preweaning growth rate of the lambs. Study Limitations/Implications: There is a strong dependency of the lambs on the milk production of the Pelibuey ewe, a factor of great relevance so that lambs can gain body weight and survive during lactation. Findings/Conclusions: Pelibuey ewes produce less milk than dairy ewes. Therefore, lambs should be weaned at a maximum of 10 weeks of lactation.

The aim of this study was to evaluate the reproductive performance and productivity of F1 Pelibuey x Blackbelly (P x B) ewes and their crosses with Dorper and Katahdin (Synthetic). 1612 lambing intervals (LI), 1265 prolificacy (Pr), 1263 adjusted litter weaning weights to 91 days (WWa) and1200 productivity (PROD) data were analysed. The statistical model included the fixed effects of maternal breed group (MBG), year of lambing (YL), season of lambing(SL), parity number (PN), litter size at weaning (LSW), lambing interval group (LIG) and first-order interactions. The effect of dam nested within MBG was included as random effect. The means ± SE for Pr, LI, WWa and PROD were 1.2 ± 0.01 lambs, 261.5 ± 1.9 days, 18.5 ± 0,1 kg and 16.8 ± 0,2 kg, of lamb weaned, respectively. Repeatabilities for the traits were also calculated. Except by maternal breed group, all main effects in the models were significant (P < 0.001); only season of lambing did not affect Pr. Repeatabilities were 0.05 ± 0.03, 0.13 ± 0.03, 0.10 ± 0.03 and 0.12 ± 0.03 for LI, Pr, WWa and PROD, respectively. Partial correlations of PROD with WWa and LI were 0.84 and -0.56, respectively. In conclusion, the P x B ewes had similar performance to the Synthetic group. The environmental factors have more importance than the genetics effects. &nbsp, El objetivo de este estudio fue evaluar el comportamiento reproductivo y productividad de ovejas F1 Pelibuey x Blackbelly (P x B) y sus cruces con Dorper y Katahdin (Sintético). Se analizaron 1.612 datos de intervalos entre partos (IEP), 1.265 de prolificidad (Pr), 1.263 de peso de la camada al destete ajustado a 91 días (PCDA) y 1.200 de productividad (PROD). El modelo estadístico incluyó los efectos fijos de grupo racial materno (GRM), año de parto (AP), época de parto (EP), número de parto (NP) y tamaño de la camada al destete (TCD), grupo de intervalos entre partos (GIP) y las interacciones de primer orden. El efecto de la madre dentro de GRM fue incluido como efecto aleatorio. Se calculó el índice de constancia de IEP, Pr, PCDA y PROD. Las medias generales de Pr, IEP, PCDA y PROD fueron 1,2 ± 0,01 corderos, 261,5 ± 1,9 días, 18,5 ± 0,1 kg y 16,8 ± 0,2 kg de cordero destetado, respectivamente. Excepto por grupo racial materno, todos los factores considerados en este estudio afectaron a todas las variables de respuesta. Asimismo la época de parto no afectó la prolificidad. Los índices de constancia estimados fueron 0,05 ± 0,03, 0,13 ± 0,03, 0,10 ± 0,03 y 0,12 ± 0,03 para IEP, Pr, PCDA y PROD, respectivamente. Las correlaciones parciales de PROD con IEP y PCDA fueron -0,56 y 0,84, respectivamente. Se concluye que la productividad del grupo racial materno P x B es similar al grupo Sintético, y que los efectos ambientales tienen más importancia que los efectos genéticos. &nbsp

El objetivo principal fue evaluar el efecto del color de la oveja (café, blanco, pinto, Blackbelly, y negro) en edad al primer parto (EPP, n = 578), prolificidad (PRO, n = 475) e intervalo entre partos (IEP, n = 438) en un rebaño de ovinos de pelo en Campeche, México. De manera secundaria se evaluaron año de parto, mes de parto, y número de parto de la oveja (primíparas, multíparas). Se analizaron datos de características reproductivas de cinco años (2006-2010) de 340 ovejas y sus crías. El rebaño se manejó bajo condiciones semiextensivas; las ovejas y sus crías pastoreaban durante el día y se encerraban toda la noche. El análisis estadístico se efectuó con el procedimiento GLM del paquete estadístico SAS mediante modelos de efectos fijos. Las medias generales de cuadrados mínimos de EPP, PRO e IEP fueron 463,9±13,0 días, 1,71±0,60 corderos nacidos por oveja parida, y 295,7±17,9 días, respectivamente. El color de la oveja influyó (P ≤ 0,05) en EPP e IEP; los menores promedios para EPP fueron para las ovejas blancas (435,8±1,4), café (438,5±2,4) y pintas (439,7±3,6), mientras que en IEP los menores promedios fueron para las ovejas pintas (284,9±6,9, blancas (288,8±1,6), y negras (291,7±5,8). Hubo efectos significativos (P ≤ 0,05) de año de parto, mes de parto, y número de parto en las tres características. Por sus menores promedios obtenidos en edad al primer parto e intervalo entre partos, se concluye que en este rebaño las ovejas blancas y pintas deberían preferirse en un programa de selección en un intento por disminuir los promedios de ambas características. The main objective of the study was to evaluate the effect of the ewe's coat color (brown, white, spotted, Blackbelly, and black) on age at first lambing (AFL, n = 578), prolificacy (PRO, n = 475), and lambing interval (LI, n = 438) in a flock of hair sheep in Campeche, México. As a secondary objective, the effects of lambing year, lambing month, and the ewe's lambing number (primiparous, multiparous) were also evaluated. Data collected on reproductive characteristics during 5 years (2006-2010) from 340 ewes and their lambs were analysed. The sheep were managed under semi-extensive conditions; ewes and their lambs were allowed to graze during the day and were penned overnight. The statistical analysis was performed with the GLM procedure of the SAS statistical package utilizing fixed effects models. Overall least-squares means for AFL, PRO, and LI were 463.9±13.0 days, 1.71±0.60 lambs born per ewe lambing, and 295,7±17,9 days, respectively. The ewe's coat color had a significant effect (P ≤ 0.05) on AFL and LI; the lowest averages for AFL were for white (435.8±1.4), brown (438.5±2,4) and spotted (439.7±3.6) ewes, while for LI the lowest averages were for spotted (284.9±6.9), white (288.8±1.6), and black (291.7±5.8) ewes. Significant effects ((P ≤ 0.05) of lambing year, lambing month, and lambing number were found on the three characteristics. Due to their lowest averages being obtained at first lambing and lambing interval, it is concluded that white and spotted ewes in this flock should be preferred for a selection program in an attempt to decrease the average of both characteristics.

The aim of this study was to evaluate the productive performance of F1Pelibuey x Blackbelly (P x B) lambs and their crosses with Dorper and Katahdin (GM). Data on 648 birth weights (BW), preweaning daily weight gains (PGW1), adjusted weaning weights to 98 d (WWa), postweaning daily weight gains (PGW2), and postweaning sale weights adjusted to 198 days (PWs) were analyzed. The statistical model included the fixed effects of breeding group (P x B and GM), birth year (2000 to 2002), birth season (dry: February to April, rainy: May to October; and windy: November to January), birth type (single and multiples) and first-order interactions. The dam effect nested within genetic group was included as a random effect. Repeatability and partial correlations between traits were also calculated. Breeding group affected PGW1, WWa, PGW2 and PWs (P < 0.05). Year of birth affected PGW1, WWa and PGW2 (P < 0.01); season of birth affected all traits (P < 0.01) and type of birth affected BW, PGW1 and WWa (P < 0.01). The breeding group x year of birth and breeding group x season of birth interactions were significant for some traits. In conclusion, the P x B breeding group had a better performance than the GM group for most of the variables analised. Single lambs born during the dry season had the best performance. &nbsp, El objetivo del estudio fue evaluar el comportamiento productivo de ovinos F1Pelibuey x Blackbelly (P x B) y sus cruces con Dorper y Katahdin (GM). Se analizaron 648 pesos al nacimiento, ganancias de peso pre (Gan1) y postdestete (Gan2), pesos al destete ajustados a 98 d de edad (Pda) y pesos a la venta ajustados a 198 d (Pva). El modelo estadístico incluyó los efectos fijos de grupo racial (P x B y GM), año de nacimiento (An: 2000 a 2002), época de nacimiento (En: seca, febrero a abril; lluvias, mayo a octubre; vientos, noviembre a enero), tipo de nacimiento (Tn: únicos y múltiples) y las interacciones simples. La madre del cordero anidada dentro de grupo racial se incluyó como efecto aleatorio. Se estimaron además los índices de constancia y correlaciones parciales entre las variables de respuesta. Grupo racial afectó Gan1, Pda, Gan2 y Pva (P < 0,05). An afectó Gan1, Pda y Gan2 (P < 0,01). Época de nacimiento influyó en todas las variables de respuesta (P < 0,01) y tipo de nacimiento afectó Pn, Gan1 y Pda (P < 0,01). En conclusión el grupo racial P x B tuvo mejor comportamiento productivo que los corderos de GM en la mayoría de las variables analizadas. Los corderos nacidos en la época seca y de tipo de parto único mostraron el mejor comportamiento productivo. &nbsp

Con el propósito de estudiar la conformación corporal de ovinos Blackbelly, se tomó una muestra aleatoria de 220 hembras y 36 machos de los rebaños del municipio de Campeche, México. La zoometría fue la base del estudio y se evaluó con 14 medidas corporales y el peso vivo de ovinos de uno, dos y tres años de edad. Se efectuaron análisis de varianza y de correlación, así como un análisis de conglomerados en los machos y hembras de uno y tres años de edad. Las medidas corporales tuvieron cambios significativos (p

El objetivo de este estudio fue evaluar el efecto del complemento alimenticio en el comportamiento productivo postdestete de corderas Pelibuey x Blackbelly manejadas bajo condiciones de pastoreo. Veintiocho corderas Pelibuey x Blackbelly se asignaron a uno de dos tratamientos: 1) complementación alimenticia baja: 0,18 Mcal de energía metabolizable (EM) cordera-1d-1 y 10,5 g de proteína bruta (PB) cordera-1d-1 o 2) complementación alimenticia media: 0,54 Mcal de EM y 31,6 g de PB cordera-1 d-1 , durante 70 días. La complementación alimenticia no afectó (p>0,05) al peso corporal y la ganancia diaria de peso (GDP). Se concluye, que en corderas Pelibuey x Blackbelly en pastoreo, la complementación alimenticia media no mejora la GDP con respecto a la complementación alimenticia baja. The objective of this study was to evaluate the effect of supplemental feed on postweaning performance of Pelibuey x Blackbelly ewe lambs managed under grazing conditions. Twenty eight Pelibuey x Blackbelly female lambs were assigned to one of two treatments: 1) low feed supplementation: 0.18 Mcal of metabolizable energy (EM) lamb-1d-1 and 10.5 g of crude protein (PB) lamb-1d-1 and 2) medium feed supplementation: 0.54 Mcal of EM and 31.6 g of PB lamb-1d-1, offered during 70 days. The supplement feed did not affect (p>0.05) body weight and average daily body weight gain (GDP). It is concluded that in grazing Pelibuey x Blackbelly ewe lambs the medium feed supplementation did not improve the daily body weight gain with respect to a low feed supplementation.

El objetivo del estudio fue evaluar la influencia de la edad al primer apareamiento sobre la eficiencia reproductiva de las corderas Pelibuey. El estudio se dividió en dos ensayos, crecimiento postdestete y manejo reproductivo. Se utilizaron 20 corderas Pelibuey. Las corderas se alimentaron con una dieta integral durante todo el estudio. En el primer ensayo, el factor de estudio fue el tipo de nacimiento (TN). Se evaluó el PV y la ganancia diaria de peso (GDP) durante 42 días. El TN no influyó (P > 0,05) el PV, GDP y edad a la que las corderas alcanzaron 28 kg P V. En el segundo ensayo, el factor de estudio fue la edad de las corderas al alcanzar los 28 kg: JOVEN (139 días) vs MADURA (169 días). Las variables evaluadas fueron: PV y corderas en estro (%). En el grupo MADURA se detectó un 43% (6/13) de corderas en estro. Mientras que en JOVEN no se detectaron corderas en estro (0/7). Se concluye que el tipo de nacimiento de las corderas no influyó sobre su eficiencia de crecimiento postdestete, ni sobre la edad a la que estas inician el manejo reproductivo a un peso fijo. La edad con la que inician el manejo reproductivo las corderas tiene un efecto importante sobre la detección del estro, en donde la mayor proporción de fallas reproductivas se presentan en corderas jóvenes. The aim of this study was to evaluate the influence of age at first mating on the reproductive performance of Pelibuey ewe lambs. The study consisted of two trials: postweaning growth and reproductive handling. Twenty Pelibuey ewe lambs were used which were fed a complete diet throughout the study. In the first trial, the studied variable was the type of birth (TN). Body weight (PV) and daily weight gain (GDP) were studied during 42 days. The TN did not influence (P > 0.05) PV, GDP and age of the ewe lambs at 28 kg PV. In the second trial, the studied variable was the age of the ewe lamb at 28 kg PV: YOUNG (139 days) vs MATURE (169 days). PV and ewe lambs in estrus (%) were studied. In the MATURE group, a 43% (6/13) of ewe lambs in estrus were detected, whereas in the YOUNG group there were no ewe lambs in estrus (0/7). It was concluded that the type of birth of the ewe lambs had no effect on the postweaning growth performance nor the starting age for reproductive handling at a determined body weight. The starting age for reproductive handling of ewe lambs had an important effect on estrus detection, and there was a high ratio of reproductive failure in young ewe lambs.