This study was conducted on two rabbit lines divergently selected for intramuscular fat (IMF) content in the Longissimus thoracis et lumborum (LTL) muscle. The aim was to estimate the direct response to selection for IMF after 10 generations, and the correlated responses in carcass quality traits, meat fatty acid content, liver fat and its fatty acid content, and in plasma metabolic markers related to liver metabolism. Selection for IMF content was successful, showing a direct response equivalent to 3.8 SD of the trait after 10 generations. The high-IMF line (H) showed a greater dissectible fat percentage than the low-IMF line (L), with a relevant difference (D_H-L = 0.63%, P_r = 1). No difference was found in liver fat content (D_H-L = −0.04, P₀ = 0.62). The fatty acid content of both LTL muscle and liver was modified after selection. The LTL muscle had greater saturated (SFA; D_H-L = 5.05, P_r = 1) and monounsaturated fatty acids (MUFA; D_H-L = 5.04, P_r = 1) contents in the H line than in the L line. No relevant difference was found in polyunsaturated fatty acids content (PUFA; P_r = 0.05); however, greater amounts of C18:2n6 (D_H-L = 3.03, P_r = 1) and C18:3n3 (D_H-L = 0.56, P_r = 1) were found in the H than in the L line. The liver presented greater MUFA (D_H-L = 1.46) and lower PUFA (D_H-L = −1.46) contents in the H than in the L line, but the difference was only relevant for MUFA (P_r = 0.86). The odd-chain saturated fatty acids C15:0 and C17:0 were more abundant in the liver of the L line than in the liver of the H line (D_H-L = −0.04, P_r = 0.98 for C15:0; D_H-L = −0.09, P_r = 0.92 for C17:0). Greater concentrations of plasma triglycerides (D_H-L = −34) and cholesterol (D_H-L = −3.85) were found in the L than in the H line, together with greater plasma concentration of bile acids (D_H-L = −2.13). Nonetheless, the difference was only relevant for triglycerides (P_r = 0.98).

High-Andean Creole cattle represent a genetic resource with significant adaptive value in high-altitude ecosystems. In this study, 151 Creole cows from the provinces of Canas and Quispicanchis (Cusco, Peru) were evaluated to characterize their morphometry, calculate zoometric indices, and establish functional biotypes. Ten morphometric parameters were measured, and eight structural indices were calculated. Four differentiated biotypes were identified through the multivariate analysis and hierarchical clustering of quantitative variables (BI, BII, BIII, and BIV). Morphological differences were statistically significant (p < 0.05) and associated with different productive orientations. Biotype I showed greater thoracic development and a compact structure, which is compatible with intermediate beefaptitude; Biotype II exhibited more elongated proportions and a lower weight, indicating a dairy tendency; Biotype III stood out for its muscle mass, thoracic depth, and pelvic width, evidencing a clear beef orientation; and Biotype IV combined a higher weight, rectangular conformation, and wide pelvis, showing potential for beef production and ease of calving. Functional differentiation was supported by Principal Coordinates Analysis (PCoA) and PERMANOVA tests. Correlations between morphometric variables and zoometric indices revealed anatomical patterns consistent with the productive functions proposed. The results highlight the morpho-functional diversity of Andean Creole cattle and their potential for conservation and improvement programs in extensive highland systems.

Introduction. The study of the sperm morphometry of the white-tailed deer (Odocoileus virginianus peruvianus) allows to characterize the sperm cells of this species for conservation purposes. Objective. To determine the sperm subpopulations according to the morphometry of the epididymal spermatozoa of the white-tailed deer, using a CASA-Morph system. Materials and methods. The study was carried out in the second semester 2016, at the Universidad Nacional San Antonio Abad del Cusco, Peru. In semen samples obtained from the caudal end of the epididymis of two deer (two and four teeth), it was determined based on the CASA-Morph system, Integrated Semen Analysis System (ISAS¨v1): the length, width, area, perimeter, ellipticity, elongation, regularity, and roughness of the sperm head were determined, also, the width, area, distance, and midpiece insertion angle of the sperm. Principal components analysis (PCA) was performed and the non-hierarchical k-means model was applied to determine the optimal number of clusters. Results. The morphometric variables were distributed in five PCAs: ellipticity, size, circularity, midpiece insertion angle, which explained 81.24 % of the total variance. The Cluster analysis determined four subpopulations (SP), SP1 grouped large, elongated cells with high elongation and ellipticity (21.76 %), SP2 composed of small and thin spermatozoa both in the head and in the midpiece (37.7 %). The SP3 was related to the presence of elongated cells with high values of midpiece width, ellipticity, and elongation (17.7 %), and SP4 grouped spermatozoa with intermediate size of the head and the midpiece (22.84 %). Conclusion. The determination of four sperm subpopulations in white-tailed deer semen can be the basis of assisted reproduction programs for this species.

El objetivo del estudio fue determinar el efecto del tratamiento con papaína en la cinética de los espermatozoides de llama. Se seleccionaron 4 llamas machos Ch’aku de 5-8 años de edad. El semen fue colectado mediante vagina artificial y maniquí. Se hicieron cuatro colectas de semen por animal con intervalos de una semana. Las muestras de semen fueron separadas en dos alícuotas. Una para su análisis en fresco y la otra para ser tratada con papaína (20 minutos). Se evaluó el volumen, filancia, concentración de espermatozoides, porcentaje de espermatozoides vivos, porcentaje de funcionalidad de la membrana espermática, y porcentaje de espermatozoides con reacción acrosomal. La movilidad de los espermatozoides y su cinética se evaluó utilizando un sistema CASA-Mot (ISAS®), determinándose la movilidad total (MT) y la movilidad progresiva (MP), así como los parámetros de cinética espermática: velocidad curvilínea (VCL), velocidad rectilínea (VSL), velocidad promedio (VAP), y los índices de rectitud (STR), linealidad (LIN) y oscilación (WOB), la amplitud del desplazamiento lateral de la cabeza (ALH) y la frecuencia de batido de la cola (BCF). El efecto de la papaína se analizó con un modelo factorial en bloques al azar. La MT no presentó diferencias significativas entre semen fresco y degelificado con papaína, pero la MP fue superior con papaína (p<0.05). Se encontró diferencias significativas (p<0.05) a favor del semen degelificado con papaína con relación al semen fresco para la VCL, VSL, VAP, LIN, STR y BCF, lo que sugiere que el tratamiento con papaína mejora la movilidad progresiva, así como la mayoría de los parámetros de cinética del espermatozoide de llama.