CRYOPRESERVED SEMEN OF Piaractus orinoquensis (SERRASALMIDAE): POST-THAW STORAGE TIMES AND ACTIVATING SOLUTIONS
Fecha de publicación: 05/01/2023

Piaractus orinoquensis is a native species from the Colombian Orinoquia and several studies have contributed to the standardization of protocols for seminal cryopreservation of this species. The main goal of this study was to evaluate the sperm motility, duration of sperm motility (DM), pH, sperm membrane integrity (SMI) and fertility of semen cryopreserved for seven years and subjected to different post-thaw storage times (PST). Semen from five males (3.04 ± 0.3 kg) was diluted 1:4 (semen:diluent) with 10 % dimethylsulfoxide, 5.5 % glucose and 12 % egg yolk in 4 mL macrotubes and frozen in liquid nitrogen. Four PST were evaluated: 0, 15, 45 and 60 min. The sperm cells were activated with 1 % NaHCO₃ (SB) and 0.9 % NaCl (SC) to determine sperm motility, DM, fertility rate, SMI and pH through PST. Significative motility reduction (p < .05) was observed through the PST and between the PST of 0 and 60 min for DM, both for treatments activated with SB and with SC. The SMI had a significant reduction (p < .05) after 60 min of post-thaw storage and the pH did not vary during PST. The fertility rate decreased significantly (p < .05) between time 0 and 60 min of PST. PST affects the seminal quality and fertility of P. orinoquensis, the best fertilization results were obtained by activating post-thawing sperm motility with 1 % SB. The long-term cryopreserved semen (seven years) of the species maintains its fertilization capacity with values like those obtained with fresh sperm.

Cryostorage of white cachama (Piaractus orinoquensis) sperm: Effects on cellular, biochemical and ultraestructural parameters
Fecha de publicación: 18/01/2023

To date, little attention has been paid to identifying the effects of long-term cryopreservation on sperm quality for Piaractus orinoquensis. The object of this study was therefore to evaluate the effect of long-term cryopreservation (24 h, 1, 6 and 12 months) on sperm motility, viability, DNA integrity, ATP content, total antioxidant capacity (TAC), morphology and sperm ultrastructure in this species. Milt samples from six males were cryopreserved in a medium containing final concentrations of 7.5% Me₂SO, 4.1% glucose and 9.0% egg yolk. The samples were frozen in liquid nitrogen (LN) vapor and stored in LN for periods of 24 h and 1, 6 and 12 months. After thawing, both the motility rate and the viability decreased significantly compared with fresh sperm; however, these parameters did not differ among the four cryopreservation times. The DNA integrity and ATP content decreased significantly after 6 months of cryopreservation. There were no significant differences in TAC values between fresh and cryopreserved sperm. The total sperm abnormalities in cryopreserved samples were about 5-fold higher than in fresh sperm; short tail was the most common defect occurring after cryostorage. The ultrastructural analysis reveals that P. orinoquensis spermatozoa consist of an ovoid head without acrosome, a cylindrical mid-piece, and a single flagellum. The nuclear fossa is located at the base of the nucleus and contains the centriolar complex. There are 1–2 ring-shaped mitochondria located in the mid-piece. The flagellum shows a 9 + 2 organization of microtubules in the axoneme. Post-thaw spermatozoa presented damage such as swelling and rupture of the plasma membrane, mitochondrial damage, loss of the electron-dense chromatin of the nucleus, and degeneration in the middle region.

Selection indexes to optimise genetic and economic progress in Colombian Blanco Orejinegro cattle
Fecha de publicación: 08/07/2022

The use of selection indexes optimises genetic and economic gains in a population. The objective of this study was to propose and compare selection indexes built with economic and statistical methodologies in Colombian Creole Blanco Orejinegro breed. Genetic, phenotypic and economic information of the breed were used to design and test the selection indexes. The weights of each selection criteria (weight at 24 months of age, age at first calving, calving interval) were estimated using phenotypic variances, eigenvectors from a principal component analysis and economic values obtained through a deterministic bio-economic model. The selection criteria with the highest weight was weight at 24 months of age, with values of 0.56 and 0.034 USD using eigenvectors and phenotypic variance, respectively. The calving interval had the highest weight using the bio-economic model, with a value of -1.3 USD. The greatest profit due to genetic selection was obtained using the economic values as weights, which increased the average expected profit to a value of 18.76 USD/cow/year. The selection indexes calculated from phenotypic and eigenvectors do not rank animals similarly to the economic selection index. It could generate less genetic and economic progress in the national selection programme for the Blanco Orejinegro breed.

Selection indexes using principal component analysis for reproductive, beef and milk traits in Simmental cattle
Fecha de publicación: 01/07/2021

Selection indexes in dual-purpose cattle should include beef, milk and reproductive traits. The principal component analysis is a multivariate technique that allows researchers to explore relationships between explanatory variables and traits of interest. The objective of this study was to construct selection indexes for tropical dual-purpose Simmental cattle based on principal components. The evaluated traits were weight at 8 months of age; age at first calving; cumulative first-lactation milk yield at 60, 150, 210 and 305 days; and first calving interval. The selection indexes were estimated as the sum of the products of the estimated breeding values for the seven traits times their respective eigenvectors for the first three principal components. The three selection indexes from principal components analysis generated favourable expected genetic progress for all the traits. However, a selection index with a high expected genetic progress for all traits could not be obtained. The principal component analysis allows breeders to have a selection index that simultaneously improves milk, beef and reproductive traits in dual-purpose Simmental cattle. Because a selection index yielding high expected genetic progress for all traits could not be achieved, the decision to use a specific selection index will depend on the specific conditions of the market, the local needs and the farmer preference.

The prevalence of Chlamydia psittaci in confiscated Psittacidae in Colombia
Fecha de publicación: 31/03/2022