Universidad de la Salle

Las siguientes son publicaciones realizadas por los investigadores de la Universidad de La Salle en Salud y Bienestar Animal.

Comparison between two fixed-time artificial insemination protocols in Brahman cows

Objective. To compare two fixed-time artificial insemination protocols (FTAI) according to the pregnancy percentage in Brahman cattle. Materials and methods. 60 cows between days 90 and 360 postpartum were selected and randomly divided into two groups. For Treatment 1 (T1; n= 30), an intravaginal device (IVD) containing 0.5 g of progesterone and 2.0 mg of estradiol benzoate were inserted on Day 0. At the time of IVD withdrawal (Day 8), 150 mg of PGF2a, im and 300 UI of eCG, im and 0.5 mg of estradiol cypionate, im were administered. FTAI was performed on Day 10, 48 - 50 h after IVD withdrawal. For Treatment 2 (T2; n= 30) an IVD was inserted on Day 0 and 0.01 mg GnRH, im were administered. At the time of the IVD withdrawal (Day 5), two doses of 0.150 mg of PGF2a were administered at midnight and noon. FTAI was performed on Day 8, 72h after IVD withdrawal, and 0.01 mg of GnRH, im was administered. FTAI was performed using semen of proven fertility. Results. Pregnancy diagnosis by rectal palpation occurred 45 days after the FTAI. T2 and T1 presented pregnancy percentages of 46.7% (14/30) and 33.3% (10/30), respectively. Conclusions. Treatment 2 is preferred in terms of results and public health.

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Assessing Financial Impacts of Subclinical Mastitis on Colombian Dairy Farms

Bovine mastitis is a dairy cattle disease with high economic impact. Subclinical mastitis (SCM) contributes to most of the financial losses. Colombia dairy sector accounts for 2.3% of the gross domestic product (GDP) and 24.3% of the livestock GDP. Milk production reaches 6,500 million liters/year from nearly 500,000 cattle farms and is mainly based on small-scale production systems. This study evaluates the financial impact of SCM and the potential for its control in three dairy farm strata in a region in Colombia. The objectives of the study were 1) to determine the perception of farmers about the SCM problem on their farms, 2) to assess prevalence and financial impact of SCM on farms and in the Area five sanitary region of the Bogota plateau, and 3) to assess costs and effectiveness of control methods of SCM. Information about disease management and decision-making process was obtained through a participatory epidemiology workshop and applying a semi-structured survey. A two-stage stratified cross sectional epidemiological study was conducted on dairy cattle from a region with approximately 400 farms and 12,000 cows, with a sample size of 55 farms. Prevalence of SCM was calculated by defining a cow as positive for the disease when any quarter had a somatic cell count (SCC) higher than 250 x 10(3) cells/ml. The prevalence of SCM in cows was 55.2%; significant differences were found between strata. Assessment of the financial impact of SCM in terms of milk losses was conducted using spreadsheet models. Milk production losses per farm ranged from 1.3% to 13.5%, and the economic impact in the region was estimated over USD $800.000 per year. The financial impact was greater in small- and medium-sized farms than large farms, and it was associated with the severity of SCC per quarter. Principal component analysis showed interactions, irrespective of the individual effect, and suggested three main groups of control interventions: application of basic milking hygiene practices, increase in the level of hygiene practices and veterinary advice, and SCM diagnosis and drycow treatment. Lack of information on management and production at farms promotes intuitive decision-making. Further research for the deeper understanding of intervention costs and effectiveness is suggested.

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Serologic survey for selected viral and bacterial swine pathogens in colombian collared peccaries (pecari tajacu) and feral pigs (sus scrofa)

In South America, wild populations of peccaries coexist with domestic and feral pigs, with poorly understood consequences. We captured 58 collared peccaries (Pecari tajacu) and 15 feral pigs (Sus scrofa) in locations of Colombia where coexistence of these species is known. Blood samples were tested for antibodies against four viral agents, classical swine fever virus (CSFV), Aujeszky's disease virus (ADV), porcine circovirus (PCV-2), and vesicular stomatitis virus (New Jersey and Indiana subtypes) and two bacterial agents, Brucella spp. and six serovars of Leptospira interrogans. The prevalence of CSFV was 5% (3/58) in collared peccaries and 7% (1/15) in feral pigs. The prevalence of PCV-2 was 7% (1/15) in collared peccaries and 67% (2/3) in feral pigs. Vesicular stomatitis prevalence was 33% (8/24) in collared peccaries and 67% (4/6) in feral pigs. Leptospira prevalence was 78% (39/50) in collared peccary and 100% (8/8) in feral pigs; bratislava, grippotyphosa, icterohaemorrhagiae, and pomona were the most frequent serovars. Also, the only white-lipped peccary (Tayassu pecari) sampled was positive for L. interrogans serovar bratislava and for vesicular stomatitis virus, New Jersey strain. No samples were positive for ADV or Brucella. The seroprevalence of antibodies against L. interrogans was similar to that observed in other studies. Icterohaemorrhagiae appears to be a common serovar among in situ and ex situ peccary populations. Positive antibodies against PVC-2 represent a novel report of exposure to this pathogen in Colombian peccaries. Our results indicate the possible transmission of various pathogens, important for pig farms, in the studied pig and peccaries.

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Sarconesin: Sarconesiopsis magellanica Blowfly Larval Excretions and Secretions With Antibacterial Properties

Larval therapy (LT) is an alternative treatment for healing chronic wounds; its action is based on debridement, the removal of bacteria, and stimulating granulation tissue. The most important mechanism when using LT for combating infection depends on larval excretions and secretions (ES). Larvae are protected against infection by a spectrum of antimicrobial peptides (AMPs); special interest in AMPs has also risen regarding understanding their role in wound healing since they degrade necrotic tissue and kill different bacteria during LT. Sarconesiopsis magellanica (Diptera: Calliphoridae) is a promising medically-important necrophagous fly. This article reports a small AMP being isolated from S. magellanica ES products for the first time; these products were obtained from third-instar larvae taken from a previously-established colony. ES were fractionated by RP-HPLC using C18 columns for the first analysis; the products were then lyophilised and their antimicrobial activity was characterized by incubation with different bacterial strains. These fractions' primary sequences were determined by mass spectrometry and de novo sequencing; five AMPs were obtained, the Sarconesin fraction was characterized and antibacterial activity was tested in different concentrations with minimum inhibitory concentrations starting at 1.2 mu M. Potent inhibitory activity was shown against Gram-negative (Escherichia coli D31, E. coli DH5 alpha, Salmonella enterica ATCC 13314, Pseudomonas aeruginosa 27853) and Gram-positive (Staphylococcus aureus ATCC 29213, S. epidermidis ATCC 12228, Micrococcus luteus A270) bacteria. Sarconesin has a significant similarity with Rho-family GTPases which are important in organelle development, cytoskeletal dynamics, cell movement, and wound repair. The data reported here indicated that Sarconesin could be an alternative candidate for use in therapeutics against Gram-negative and Gram-positive bacterial infections. Our study describes one peptide responsible for antibacterial activity when LT is being used. The results shown here support carrying out further experiments aimed at validating S. magellanica AMPs as novel resources for combating antibacterial resistance.

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