Effect of intramammary infection on milk electrical conductivity in Murciano-Granadina goats

Abstract

Measurements of electrical conductivity (EC) of milk are used in mastitis detection in cows due to the low cost, possibility of automation, and rapid diagnosis, but the literature about EC measurement in goats is scarce. In this study, we studied the effect of the establishment of intramammary infection (IMI) on EC of goat milk by gland using daily measurements. Additionally, the effects on milk yield, somatic cell count (SCC), and mineral content were analyzed. Eight primiparous and 10 multiparous Murciano-Granadina goats free from IMI were included in the study. Health conditions of the participating animals were monitored for 16 d and then various unfavorable health situations that may arise on commercial farms were simulated to increase the chances of IMI. Once the IMI was confirmed, the experiment continued for another 16 d. Statistical analysis was conducted using a linear mixed model considering several periods regarding the establishment of the infection and whether it affected one or both glands in the animal. The establishment of IMI caused a significant increase of EC, SCC, and chlorides in the infected glands, whereas the sodium:potassium ratio and the ratio of EC between collateral glands showed significant increases only in bilaterally infected animals. The microorganisms that caused greater increases of EC were Staphylococcus aureus and a gram-negative bacterium. Changes due to other isolated microorganisms (coagulase-negative staphylococci and streptococci) were small. No significant differences in milk yield were determined. The significant effect of infection on EC in the affected glands suggests that the use of a system based on daily readings of EC could be useful in IMI detection of goats.

On-Line Monitoring of Milk Electrical Conductivity by Fuzzy Logic Technology to Characterise Health Status in Dairy Goats

“…This is probably due to the lack of a significant decrease of MY in non-healthy glands, also worsened by an insignificant correlation between deviations of MY and HS, which affected the accuracy of the model. These results seem to confirm that MY is not a useful parameter to detect HS in dairy goats, as found by Díaz et al (2012). However, in dairy cows the decrease of MY is generally more significant in cows with mastitis.…”

“…However, in this study a higher prevalence of bilateral infections was observed (47.9 vs 32.3%). Díaz et al (2012) found a significant increase of EC only in cases of bilateral infection. Higher prevalence of bilateral infections observed in this study could therefore explain the different significance that data showed in terms of the relationship between EC and HS.…”

“…Furthermore, SCC in infected glands was approximately twice as high as in healthy glands (from 5.03 for the first fraction of milking to 5.31 log SCC for the third fraction of milking in healthy glands, compared with 5.47 for the first milking fraction and 5.66 log SCC for the third fraction of milking in cases of infected glands). Díaz et al (2012), in a study on 18 Murciano-Granadina goats at the third month of lactation, found a significant increase of SCC after infection of a gland, which was not observed in collateral healthy glands or in glands from goats free from infection. In another study conducted by Diaz et al (2011) over 7 months of lactation on 105 Murciano-Granadina goats from 3 different farms reported a significant increase in the average value of log SCC during lactation (from 5.83 for the first month of lactation to 6.03 for the seventh month of lactation).…”

“…Also the rules for the fuzzy inference step were mainly derived from the well (Cavero et al, 2006;de Mol and Woldt, 2001;Díaz et al, 2011Díaz et al, , 2012Salehi et al, 2000;Ying et al, 2004) and different combinations of these rules were evaluated. The determination of the HS of the goat with membership functions equal to very high, high, middle and low probability of disease were the outcomes of the combined input variables.…”

Goat mastitis detection using daily records of milk conductivity: comparative results of different algorithms

“…There are several factors other than mastitis related to EC, including differences between animals, so that, in dairy cows, methods that employ an absolute EC threshold for all the animals for mastitis detection are not accepted, even if EC is measured in the complete milking or at gland level. Studies in dairy goats (Ying et al 2002;Diaz et al, 2011Diaz et al, , 2012Romero et al 2012) have shown significant effects of parity, lactation stage, farm, and the analyzed fraction, in addition to mammary infection.…”