Publicação
Phenotypic and nosological factors affecting milk production and composition in serrana goats
| Resumo: | The main objective of the present research work was to contribute to the scientific advance of mastitis diagnose in goats, namely for the Serrana goat breed, Transmontano ecotype. This research highlights the multiplicity of infectious and non-infectious factors, which influence somatic cells count (SCC), contributing to understand the conventional diagnostic methods and its limitations. Besides that, it supports the implementation of new technologies, including infrared thermography and ultrasonography as tools for sustainable mastitis control. Our first approach to the udder health status was in order to understand the extent to which microbiological contamination, and the consequent increase in somatic cells, interferes in the composition of milk used for cheese manufacture. High SCC has been observed, and the percentage of fat content and lactose has been negatively correlated with log10 SCC, both indicating severe udder health problems. The negative correlation value of the total bacterial count suggested environmental contamination and cooling problems in milk storage. Our second study aimed to evaluate the seasonal variation of milk composition and SCC of Serrana dairy goats reared in mountains along a year. The mean±SD percentage of milk protein, fat, lactose and solids-not-fat were 3.63±0.24, 5.22±0.70, 4.72±0.25 and 8.92±0.44, respectively. The mean fat/protein ratio, Log 10 SCC and Log 10 of total bacteria count per mL were 1.45±0.21, 3.39±0.19 and 2.55±0.53, respectively. A significant effect of month was found for all the parameters studied (P for production purposes and that an improvement of production system management can play an important role in mitigating milk yield losses. The mammary gland development is strictly related to the lactational performance. Being mastitis the main cause for decreased milk quality and quantity, our fourth study aimed to characterize the external morphological traits of the mammary gland and their relations with the presence of intramammary infection and SCC. It was observed that bifurcated pendular udders, with vertical loose teats and located close to each other, are more likely to have intramammary infection, and have the highest SCC. The udder shape, symmetry, degree of suspension and degree of separation parameters have shown to be significantly different depending on SCC. Considering SCC limitations, we wanted to explore diagnostic techniques already being used in cattle for mastitis diagnosis. Hence, the fifth study evaluated whether infrared thermography (IRT) and B-mode ultrasonography could become diagnosis tools to be used as first field techniques. Bacteriological examinations, SCC and California Mastitis Test (CMT) were performed on milk samples from both udder halves. Significant differences were found between bacterial groups according to lactation number and stage (p <0.005). SCC and CMT were significantly different according to the isolated bacterial species (p<0.005) Significant differences were found in the minimum (p <0.001) and mean (p <0.01) udder surface IRT temperatures and for the measured surface IRT temperature of teats (p <0.01), between control group (negative to microbiological evaluation; n=29) and the different isolated bacterial groups, such as Staphylococcus aureus (n=12) and Coagulase-negative staphylococci (n=12), but not with Streptococcus spp. (n=13) and yeasts (n=11). Regarding parenchyma ultrasonographic images, numerical pixel intensity analysis revealed that mean, standard deviation, minimum and maximum numerical pixel values did not differ of the control group neither depending on each bacteria or yeast group. In conclusion, a set of specific phenotypic factors were determined to be considered in mastitis control programs in Serrana dairy farms, the Transmontano ecotype. Infrared thermography appears to have the potential for diagnosing mastitis in situ, but further studies are needed to improve this technique. |
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| Autores principais: | Margatho, Gisele da Costa |
| Assunto: | Caprinos Leite |
| Ano: | 2022 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Trás-os-Montes e Alto Douro |
| Idioma: | inglês |
| Origem: | Repositório da UTAD |
| Resumo: | The main objective of the present research work was to contribute to the scientific advance of mastitis diagnose in goats, namely for the Serrana goat breed, Transmontano ecotype. This research highlights the multiplicity of infectious and non-infectious factors, which influence somatic cells count (SCC), contributing to understand the conventional diagnostic methods and its limitations. Besides that, it supports the implementation of new technologies, including infrared thermography and ultrasonography as tools for sustainable mastitis control. Our first approach to the udder health status was in order to understand the extent to which microbiological contamination, and the consequent increase in somatic cells, interferes in the composition of milk used for cheese manufacture. High SCC has been observed, and the percentage of fat content and lactose has been negatively correlated with log10 SCC, both indicating severe udder health problems. The negative correlation value of the total bacterial count suggested environmental contamination and cooling problems in milk storage. Our second study aimed to evaluate the seasonal variation of milk composition and SCC of Serrana dairy goats reared in mountains along a year. The mean±SD percentage of milk protein, fat, lactose and solids-not-fat were 3.63±0.24, 5.22±0.70, 4.72±0.25 and 8.92±0.44, respectively. The mean fat/protein ratio, Log 10 SCC and Log 10 of total bacteria count per mL were 1.45±0.21, 3.39±0.19 and 2.55±0.53, respectively. A significant effect of month was found for all the parameters studied (P for production purposes and that an improvement of production system management can play an important role in mitigating milk yield losses. The mammary gland development is strictly related to the lactational performance. Being mastitis the main cause for decreased milk quality and quantity, our fourth study aimed to characterize the external morphological traits of the mammary gland and their relations with the presence of intramammary infection and SCC. It was observed that bifurcated pendular udders, with vertical loose teats and located close to each other, are more likely to have intramammary infection, and have the highest SCC. The udder shape, symmetry, degree of suspension and degree of separation parameters have shown to be significantly different depending on SCC. Considering SCC limitations, we wanted to explore diagnostic techniques already being used in cattle for mastitis diagnosis. Hence, the fifth study evaluated whether infrared thermography (IRT) and B-mode ultrasonography could become diagnosis tools to be used as first field techniques. Bacteriological examinations, SCC and California Mastitis Test (CMT) were performed on milk samples from both udder halves. Significant differences were found between bacterial groups according to lactation number and stage (p <0.005). SCC and CMT were significantly different according to the isolated bacterial species (p<0.005) Significant differences were found in the minimum (p <0.001) and mean (p <0.01) udder surface IRT temperatures and for the measured surface IRT temperature of teats (p <0.01), between control group (negative to microbiological evaluation; n=29) and the different isolated bacterial groups, such as Staphylococcus aureus (n=12) and Coagulase-negative staphylococci (n=12), but not with Streptococcus spp. (n=13) and yeasts (n=11). Regarding parenchyma ultrasonographic images, numerical pixel intensity analysis revealed that mean, standard deviation, minimum and maximum numerical pixel values did not differ of the control group neither depending on each bacteria or yeast group. In conclusion, a set of specific phenotypic factors were determined to be considered in mastitis control programs in Serrana dairy farms, the Transmontano ecotype. Infrared thermography appears to have the potential for diagnosing mastitis in situ, but further studies are needed to improve this technique. |
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