Scielo RSS <![CDATA[Austral journal of veterinary sciences]]> vol. 50 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Improvisation or planning the control of an infectious disease outbreak?]]> <![CDATA[The effects of periparturient events, mastitis, lameness and ketosis on reproductive performance of Holstein cows in a hot environment]]> ABSTRACT: The aim of this study was to determine the association among periparturient events such as mastitis, lameness (infectious and non-infectious) and ketosis and the reproductive performance of high producing Holstein cows in a hot environment. The health status and reproductive data variables were recorded from 6,566 completed lactations in a large dairy operation. A logistic regression model with the stepwise procedure was used, considering the occurrence of the health problems during the pre-breeding period as fixed effect risk factors and reproductive variables as dependent variables. Pregnancy rate of cows contracting clinical mastitis (CM) around the period of first inseminations was five percentage points lower than cows without this disease. Cows with CM shortly before or after the first service had twice the risk of requiring more than three services per pregnancy than cows with healthy udders. Cows experiencing abortion, laminitis or metritis were two times more likely to require &gt;3 services per pregnancy than cows not experiencing these reproductive disorders. Cows experiencing lameness, mastitis and metritis presented a significantly longer interval between calving and pregnancy compared to healthy cows. Ketosis and lameness increased the odds of a cow of being inseminated for the first time after 70 days in milk. In conclusion, these results suggest that abortion, ketosis, CM, retained placenta (RP), metritis, and lameness are associated with decreased reproductive performance in high producing Holstein cows subjected to thermal stress. <![CDATA[Physiological and behavioural response of two dairy cows’ genotypes during summertime in the central region of Chile]]> ABSTRACT: Heat stress has been recognised as a serious problem in dairy farms. The study goal was to assess the effects of climatic conditions on physiological and behavioural responses of dairy cows in Central Chile. Data of tympanic temperature (TT), panting score, respiration rate (RR), and shade utilization of cows from two genotypes, Holstein (H) and Holstein x Montbeliarde (HM), were collected twice per day (AM/PM) during three periods of the summer season in Central Chile. Moreover, three thermal comfort indices: Comprehensive climate index (CCI), temperature humidity-index (THI), and adjusted THI were estimated using meteorological data. The hour of each day was classified as “Normal” or “Stressful” based on CCI threshold of 25 °C. Statistical analysis included ANOVA, repeated measures analysis and Chi square test (a=0.05). There was an interaction of genotype x CCI condition x period (P=0.0026) with the highest TT of both genotypes under a stressful condition within each period. In addition, interactions of genotype x hour (P&lt;0.0001) and genotype x CCI condition (P&lt;0.0002) were also observed. The HM cows showed greater TT than H cows in both CCI conditions. The RR was higher during the afternoon and a greater proportion of cows used shade at “Mild” and “Moderate” CCI categories (P&lt;0.001). Both genotypes showed some degree of heat stress, but cool nights and shade seem to be enough to allow to cows’ cope with the challenging diurnal conditions observed in the summer season. A study of these effects on milk production is necessary to confirm or discard the previous. <![CDATA[Energetic metabolic profile of ewes presenting low body condition score induced to subclinical hypocalcemia in early postpartum]]> ABSTRACT: The aim of the present study is to assess plasma concentrations of metabolites related to energy balance in ewes showing low body condition score (BCS) induced to subclinical hypocalcemia in early postpartum. Sixteen crossbred ewes (Ideal x Corriedale) presenting BCS &lt;3 were divided in two groups: 1) control group (n = 9), which received no treatment, and 2) hypocalcemia group (n = 7), which was subjected to twelve hours of induced subclinical hypocalcemia through intravenous Na2EDTA infusion six hours postpartum. Ionized calcium levels were monitored and kept between 0.62 and 0.87 mmol/L. All ewes were subjected to daily blood sampling for five days in order to set the postpartum metabolic profile. There was no interaction between day and treatment in total and ionized calcium concentrations (P&gt;0.05), whereas the mean concentrations of these marks after five days were lower in the hypocalcemia group (P&lt;0.05). However, neither the mean group were different at glucose, non-esterified fatty acids, beta-hydroxybutyrate and insulin (P&gt;0.05) level. These results evidence that, despite the subclinical hypocalcemia induction at early postpartum, ewes presenting low body condition do not change the concentrations of energy balance-related metabolites in the following five days. <![CDATA[The densities of fiber follicles in the Karakaç, Norduz, and Zom sheep and a comparative analysis]]> ABSTRACT: This study aimed to determine the densities of fiber follicles in the skin of the Karaka§, Norduz, and Zom sheep breeds and to carry out a comparative analysis between them. The study included a total of 36 animals aged 1-2 years and 3-4 years. Skin samples were obtained through biopsies taken from the right sides of the animals to determine the densities and ratios of the fleece follicles. Examination of these samples revealed that the primary follicle densities of the three sheep breeds (Karaka§, Norduz and Zom) were 3.11 ± 0.42, 3.14 ± 0.49 and 3.34 ± 0.59, while the secondary follicle densities were 8.42 ± 1.48, 8.51 ± 1.54 and 6.36 ± 1.44. The secondary to primary (S/P) follicle ratios of the sheep were 2.71 ± 0.70, 2.79 ± 0.69 and 1.85 ± 0.36, respectively. The primary follicle densities of the Karaka§, Norduz and Zom sheep were statistically similar for both age groups. The density of secondary follicles and S/P ratio decreased with age in both age groups. The similarity of the S/P ratios to those from other local sheep breeds suggest that Karaka§, Norduz, Zom sheep can be included in the sheep group that has coarse fleece. <![CDATA[Effect of climate and insemination technique on reproductive performance of gilts and sows in a subtropical zone of Mexico]]> ABSTRACT: The objective of this study was to analyse the reproductive performance of hybrid (Yorkshire x Landrace) gilts/ sows in relation to temperature-humidity index (THI) at artificial insemination (AI), season of AI, occurrence of estrus &gt;8 d post- weaning, repeated estrus, insemination technique (cervical, CAI or post-cervical, PCAI) and parity. Data included 8851 reproductive records (1771 for gilts and 7080 for sows) from a pig farm in a sub-tropical zone (THI ranged from 72.9 in January to 81.8 in June). A decrease in pregnancy rate (PR, 89.8 vs 93.0%; P&lt;0.01) and a tendency to decline farrowing rate (FR, 87.9 vs 90.3%; P=0.07) following AI during high THI (&gt;82), compared to AI at &lt;74 THI were observed. The spring and summer season were associated with decreased (P&lt;0.01) PR compared with fall and winter (90.0% vs 93.0%). Likewise, FR decreased in spring and summer compared to fall and winter (88.5% vs. 90.9%). FR was higher (P&lt;0.01) in non-repeat breeders compared with that of repeat-breeders (90.3% vs 76.2%). Litter size increased (P&lt;0.01) from 10.8 ± 3.2 to 11.1 ± 3.1 pigs when the interval from weaning to estrus was &gt;8 d. The insemination technique did not affect PR and FR but the litter size decreased (P&lt;0.05) from 11.3 ± 3.0 to 11.1 ± 2.9 pigs when PCAI was used compared to CAI. This study reaffirms the negative effects of the hot season on reproductive performance of gilts/sows, although thermal stress at AI did not cause foetal losses. Also, there is no advantage in using the PCAI as compared to the CAI in gilts/sows with high numbers of sperm cells per AI. <![CDATA[Probiotics on performance, intestinal morphology and carcass characteristics of broiler chickens raised with lower or higher environmental challenge]]> ABSTRACT: This study aimed to evaluate the effect of probiotics on performance, intestinal morphology and carcass characteristics of broiler chickens housed on lower or higher environmental challenge. Three hundred male Cobb chicks were distributed into four groups in completely randomised design with treatments arranged in a 2 x 2 factorial scheme to evaluate effects of two diets (with or without probiotics) and two environmental conditions (lower or higher challenge), totaling four treatments with five replications with 15 birds per box. Probiotics were added on diets and were composed of Lactobacillus acidophilus, Bacillus subtilis, Bifidobacterium bifidum and Enterococcus faecium. The environment with lower challenge was made up of new wood shavings used as litter, low bird density (8 birds/m2) and daily-cleaned bell drinkers. The environment with higher challenge was made up of re-used wood shavings used as litter (after three broods of broilers), bird density of 16 birds/m2 with bell drinkers cleaned every two days. No significant interaction between diet and environmental challenge was found for any of the variables evaluated. Performance, slaughterhouse variables and chemical carcass composition were not affected by the use of probiotics. Chicks receiving diets without probiotics had lower intestinal crypt depth (267.1 vs. 316.6 pm, P=0.0068). Birds raised in the environment with higher challenge decreased feed intake (4,660 vs 5,020 g, P=0.0422), weight gain (2,610 vs 2,810 g, P= 0.0054), drumstick and thigh yield (21.98 vs 24.14 %, P=0.0354), and increased crypt depth (325.2 vs 258.5 pm P=0.0009). In conclusion, the probiotic does not promote satisfactory improvements, regardless of the environmental challenge. <![CDATA[Assessment of persistent organic pollutants and their relationship with immunoglobulins in blood of penguin colonies from Antarctica]]> ABSTRACT: Persistent organic pollutants (POPs) may affect the immune system of seabirds, and some field studies have examined this effect. There are evidences that POPs cause negative effects on the immune system, but in Antarctic penguins data are scarce. In order to assess the risks that POPs may have on wild animals, some immunological studies constitute a good alternative. Determining the levels of immunoglobulins can deliver relevant information about the potential impact of POPs in seabirds from different environments. However, there are very few records in penguins so far. The aim of the present work was to quantify the concentrations of polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (LDDT), endosulfans, and immunoglobulin IgY in blood samples of colonies of chinstrap penguins (Pygoscelis antárctica) that inhabit in the Antarctic Peninsula area. Analysis of POPs in blood samples was carried out through extraction with QuEChERS method, followed by gas chromatography. Detection of IgY concentrations was achieved by ELISA test, using anti-chicken antibodies. There was some significant correlation between immunoglobulin and the presence of PCBs and endosulfans. Even though the levels of these pollutants are low to cause any biological effect on the birds, the results are indicating some influence on the IgY concentrations in penguin blood. <![CDATA[Comparison of common tests performance for <em>Mycobacterium bovis</em> infection diagnosis in low prevalence dairy cattle herds of southern Chile]]> ABSTRACT: The aim of the present study was to assess the performance of routinely used diagnostic tests to detect M. bovis infection in cattle populations with very low infection prevalence. A cross-sectional study was performed using 609 animals from 17 herds that were sampled for blood interferon, and tested with the caudal fold tuberculin test (CFT). It was planned that animals which showed CFT positive results were sent to the slaughterhouse for post mortem confirmation testing. However, not all the animals considered in the initial sampling were culled. Paired population proportions of positive results for the different diagnostic tools were compared. Apparent sensitivity and specificity was also estimated. Overall, intradermal tuberculin based diagnostics showed better performance in comparison to interferon based test, even though interferon was slightly more specific. From these results, it may be suggested that specific cut-off lines for interferon based techniques for certain areas with particular low bTB prevalence should be considered, as well as the modification of more specific antigens and the use of better combinations of PPDs if in vitro testing is intended must be taken into consideration. The uncertain role of interference bacteria that could be affecting the results of the in vitro analysis must be considered, and perhaps this could explain the apparent lack of consensus of the results obtained in Chile versus the ones obtained elsewhere. More studies must be performed in order to assess this issue. <![CDATA[Relationship between the nutritional state before the breeding period and the reproductive success in alpacas <em>(Vicugna pacos)</em> from the Chilean Puna]]> ABSTRACT: A poor nutritional state may explain the low fertility rates of domestic camelids from Puna herds. The objective of this study was to determine the relationship between the nutritional state of alpacas before the breeding period and their reproductive success. The body live weight (BLW) and body condition score (BCS; scale from 1-5) of 35 non-pregnant non-lactating alpacas from the Caquena bofedal in Chile were registered previous to the breeding period. In addition, blood samples were collected (heparinised tubes) to determine the plasma concentration of cholesterol (CHOD-PAP method), triglycerides (GPO-PAP method) and NEFA (enzymatic colorimetric method). Pregnancy was determined by trans-rectal ultrasonography (7.5 MHz, Samsung Madison, Korea) at the end of the breeding period. Data from Pregnant and Non-Pregnant groups were compared using Mann-Whitney U test (SPSS programme; P&lt; 0.05). Pregnant (n=20) and Non-pregnant groups (n=15) had similar BLW (47.1 ± 8.8 compared to 52.8 ± 11.1 kg, respectively; P = 0.9), BCS (3.0 ± 0.4 compared to 3.1 ± 0.4, respectively; P = 0.5), plasma cholesterol (1.0 ± 0.4 compared to 0.9 ± 0.3 mmol/l, respectively; P=0.7), triglycerides (0.3 ± 0.1 compared to 0.4 ± 0.1 mmol/l, respectively; P = 0.3), and NEFA (0.6 ± 0.4 compared to 0.8 ± 0.6 mmol/l, respectively; P = 0.1) before the breeding period. NEFA values of both groups showed evidence of negative energy balance. The nutritional state of alpacas before the breeding period did not explain the differences obtained in their reproductive success. <![CDATA[Energy value of unfermented dried grape pomace as substitute of alfalfa hay in diets for growing lambs]]> ABSTRACT: The energy value of unfermented dried grape pomace (DGP) was evaluated in an 84 d feeding trial on 16 PelibueyxDorper lambs (17.8 ± 2.0 kg). The control diet contained 90% mature alfalfa hay and 10% concentrates. Treatments consisted in the replacement (DM basis) of alfalfa hay by DGP at 0, 10, 20 or 30%. Lambs were blocked by weight and assigned individually to pens. Increasing DGP level in diet tended (P=0.06) to decrease daily gain and linearly increased (P=0.04) dry matter intake (DMI); thus, feed efficiency, dietary energy, and observed-to-expected diet NE were linearly decreased (P&lt;0.01), increasing linearly (P&lt;0.01) observed-to-expected DMI coefficient as DGP level was increased in the diet. There were no effects of treatments on carcass characteristics. Using the replacement technique, the energy value of DGP were 0.80, 0.75 and 0.67 Mcal ENm/kg DM, for 10, 20 and 30% of inclusion, respectively. It is concluded that the estimated NE of DGP at 10% inclusion level in the diet is very similar to the NE value assigned by the NRC (2007) for the fermented DGP. Increasing the inclusion of DGP levels beyond 10% decreases its energy value, maybe due to the negative associative effects of chemical compounds (such as phenols) naturally contained in DGP.