Avaliação do comportamento de vacas leiteiras num sistema voluntário de ordenha
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2015-12-03
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O presente trabalho tem como objetivo avaliar o comportamento das vacas leiteiras em sistemas de ordenha robotizada (SOR). Desta forma, pretende-se estudar sobretudo, a frequência de ordenha destes animais ao longo de uma lactação completa, a distribuição das suas visitas ao longo de 24 horas, bem como, a influência do nível produtivo nestes parâmetros.
Numa exploração leiteira com sistema de ordenha robotizada, foram recolhidos dados relativos a 162 animais, através do programa do robot, que nos forneceu o historial de visitas de cada animal ao dispositivo. Para este trabalho, foram utilizados os dados de 18 vacas, todas de primeira lactação, onde se considerou apenas os dias de lactação entre o dia 1 e 305, que foram divididas em 3 grupos com 6 animais cada. Os grupos foram constituídos em função do nível produtivo individual: baixo, médio e alto.
Para a realização do tratamento estatístico recorreu-se ao programa JMP efetuando-se o cálculo da estatística descritiva e determinando-se o efeito dos diferentes fatores na frequência de ordenha, através do modelo ANOVA e do teste Tukey para comparação de médias.
Os resultados mostraram que, de um modo geral, os diferentes lotes seguem o mesmo padrão, no que respeita à frequência da hora de ordenha. As visitas de ordenha foram menores nos períodos em que o robot (SOR) efetua a sua limpeza e no período em que se realiza a distribuição do alimento na manjedoura. Em contrapartida, os picos da frequência de ordenha ocorreram após a realização destas atividades e durante a condução dos animais ao SOR.
Relativamente ao efeito do lote no número de ordenhas, constatou-se que, houve diferenças altamente significativas (P<0,001), onde o lote alto apresentou uma frequência de ordenha mais elevada (3,7 visitas), relativamente aos lotes médio (3,2 visitas) e baixo (2,9 visitas).
Na fase crescente da curva de lactação, verificou-se que, o número médio de ordenhas, nos três lotes, aumentou. Na fase seguinte da curva, entre o dia 75 e 250, averiguou-se uma tendência para manter mais ou menos constante o número médio de visitas de ordenha. Nesta fase, notou-se claramente que, o lote alto evidenciou um maior número de visitas de ordenha. Por fim, na fase descendente da curva de lactação, observou-se um decréscimo no número de visitas, exceto no lote alto, que manteve.
Segundo o modelo de Wood, a produção no pico de lactação diferiu entre o lote alto e médio, relativamente ao baixo (41,0 ± 1,1; 38,2 ± 1,1; 33,9 ± 1,1; respetivamente, com P=0,02). Quanto à produção total de leite, registaram-se diferenças estatisticamente significativas entre os lotes (P=0,0010), onde o lote alto (12389,8 ± 370,7) foi significativamente diferente do lote baixo (9887,8 ± 370,7). Os dias de lactação, o dia do pico e a persistência da lactação não foram afetados pelo nível produtivo dos animais.
Na estimativa da produção total de leite, pelo método de Fleischmann e pelo modelo de Wood, não foram evidenciadas diferenças significativas entre os dois modelos (P>0,05). No entanto, estes diferiram significativamente da produção real (P<0,001), uma vez que a sobrestimaram. Nesta análise, não se verificou nenhuma interação significativa entre o lote e o modelo de cálculo da produção de leite na lactação (P=0,2639).
The present study aims to evaluate the behavior of dairy cows in an Automatic Milking System (AMS). It is intended mainly to study the behavior of milking dairy cows in a AMS throughout a full lactation, the distribution of their visits over 24 hours as well as the influence of the production level in these parameters. Data were collected on a dairy farm with 162 animals which has an AMS. The AMS software provided the pattern of visits to the AMS and milk production of each animal. For this work data from 18 cows were used, all in first lactation, which was considered only the days in milk between day 1 and 305. These animals were divided into 3 groups of 6 animals each. The groups were formed on the basis of individual production level: low, medium and high. To perform the statistical analysis it was used the JMP program. It was performed the calculation of descriptive statistics and the effect of different factors on the milking frequency, via ANOVA model and Tukey test for comparison of means. The results show that, in general, different groups follow the same pattern in relation to the milking frequency in AMS. The visits to AMS were lower in periods when system performs its cleanliness and during the food distribution period in the feed bunk. Conversely, peak frequency of milking occurred after these activities and during the conducting of animals to the AMS. When it was considered the group effect it was observed statistically significant differences (P<0,0001) between the high group, as expected, showed a high frequency of milking (3,7 visits) in relation to the other two groups (3,2 and 2,9 visits for medium and low groups, respectively). In the growing stage of the lactation curve, it was found that the average number of milking increase for all groups. In the next phase of the curve, between 75 and 250 days, it was observed a tendency to maintain constant average number of milking visits for the groups. Nevertheless at this stage, it is noted that the high group showed a greater number of milking visits than the others. Finally, in the descending phase of the lactation curve, there was a decrease in the number of visits, except in high group that remained with the number of visits observed in the previous phase. According to Wood's model, production at peak lactation was different between the high and medium and the low groups (41,0 ± 1,1; 38,2 ± 1,1; 33,9 ± 1,1 kg, respectively, P = 0,020). For the total milk production, there were statistically significant differences between groups (P=0,0010), where the high group was significantly different from the low group (12389 vs 9887 kg). The days of lactation, the peak day and persistency of lactation were not affected by the productive level of animals. In estimating the total milk production by the Fleischmann and Wood methods there were no significant differences between these two models (P>0,05). However, these methods differ from the actual milk production (P< 0,0001).
The present study aims to evaluate the behavior of dairy cows in an Automatic Milking System (AMS). It is intended mainly to study the behavior of milking dairy cows in a AMS throughout a full lactation, the distribution of their visits over 24 hours as well as the influence of the production level in these parameters. Data were collected on a dairy farm with 162 animals which has an AMS. The AMS software provided the pattern of visits to the AMS and milk production of each animal. For this work data from 18 cows were used, all in first lactation, which was considered only the days in milk between day 1 and 305. These animals were divided into 3 groups of 6 animals each. The groups were formed on the basis of individual production level: low, medium and high. To perform the statistical analysis it was used the JMP program. It was performed the calculation of descriptive statistics and the effect of different factors on the milking frequency, via ANOVA model and Tukey test for comparison of means. The results show that, in general, different groups follow the same pattern in relation to the milking frequency in AMS. The visits to AMS were lower in periods when system performs its cleanliness and during the food distribution period in the feed bunk. Conversely, peak frequency of milking occurred after these activities and during the conducting of animals to the AMS. When it was considered the group effect it was observed statistically significant differences (P<0,0001) between the high group, as expected, showed a high frequency of milking (3,7 visits) in relation to the other two groups (3,2 and 2,9 visits for medium and low groups, respectively). In the growing stage of the lactation curve, it was found that the average number of milking increase for all groups. In the next phase of the curve, between 75 and 250 days, it was observed a tendency to maintain constant average number of milking visits for the groups. Nevertheless at this stage, it is noted that the high group showed a greater number of milking visits than the others. Finally, in the descending phase of the lactation curve, there was a decrease in the number of visits, except in high group that remained with the number of visits observed in the previous phase. According to Wood's model, production at peak lactation was different between the high and medium and the low groups (41,0 ± 1,1; 38,2 ± 1,1; 33,9 ± 1,1 kg, respectively, P = 0,020). For the total milk production, there were statistically significant differences between groups (P=0,0010), where the high group was significantly different from the low group (12389 vs 9887 kg). The days of lactation, the peak day and persistency of lactation were not affected by the productive level of animals. In estimating the total milk production by the Fleischmann and Wood methods there were no significant differences between these two models (P>0,05). However, these methods differ from the actual milk production (P< 0,0001).
Descrição
Dissertação de Mestrado em Engenharia Zootécnica
Palavras-chave
Produção leiteira , Vaca leiteira , Lactação , Intervalo de ordenha , Sistema de ordenha robotizada