Effect of estrus synchronization on daily somatic cell count variation in goats according to lactation number and udder health status

Abstract

Two repeated experiments were carried out in 2 different years to study the effect of estrus on somatic cell count (SCC) in dairy goats. In the first year, 36 Murciano-Granadina goats were used [12 primiparous and 24 multiparous; 22 healthy and 14 with an intramammary infection (IMI)] and, after a 6-d pre-experimental period, were divided into 2 groups according to lactation number, udder health status, SCC, and milk production. One group was kept as a control, whereas the other received an estrus synchronization hormonal treatment lasting 11d. At 24, 48, and 72h after cessation of the hormone treatment, goats were placed in contact with a buck to confirm that they were in estrus. For 32 consecutive days (6 pre-experimental, 11 in hormone treatment, and 15 post-treatment) the SCC per gland and udder were monitored in all animals. In the second year, we repeated the same experimental design using a total of 38 Murciano-Granadina breed goats (12 primiparous and 26 multiparous; 26 healthy and 12 with IMI). Throughout this experiment, milk yield and composition were also recorded daily for each goat. Upon termination of the hormonal treatment, the SCC in udder milk increased significantly in the treatment group compared with the control group over 3 consecutive days. This increase was observed for year (1 and 2), parity (primiparous and multiparous), and udder health status (healthy and IMI). The log10 SCC (cells/mL) increased from 5.5±0.09 before estrus to 6.04±0.09 during treatment; therefore, the geometric mean of the SCC increased 3.5 times during treatment. The maximum values obtained in healthy glands of primiparous goats (geometric mean=0.37 million cells/mL) were lower than in healthy glands (1.1 million cells/mL) or infected glands (1.7 million cells/mL) of multiparous goats. The increase in SCC observed during estrus (200% increase in geometric means) could not be explained by the changes in milk production, which only fell by 13%. During estrus, the percentage of protein and dry matter in the milk also increased significantly. We concluded that it is necessary to consider the presence of estrus to correctly interpret milk SCC, as an indirect method for detecting IMI or as a commercial milk quality parameter.

Effect of stress on somatic cell count and milk yield and composition in goats

“…This work has experimentally demonstrates, for the first time to our knowledge, that stress can cause a marked elevation of SCC in lactating goats of parity ≥3. This increase is transitory with a duration of 1 to 3 days, which is similar to the effect of estrus in goats (Mehdid et al, 2013). Although the increase of SCC presented a great individual variability (from 2.5-fold to 35-fold higher than the SCC values previous to stress), the average was higher than the increase produced by estrus (6-fold increase in this work and 3.5 and 4-fold for the estrus; Mehdid et al, 2013;Moroni et al, 2007).…”

“…This increase is transitory with a duration of 1 to 3 days, which is similar to the effect of estrus in goats (Mehdid et al, 2013). Although the increase of SCC presented a great individual variability (from 2.5-fold to 35-fold higher than the SCC values previous to stress), the average was higher than the increase produced by estrus (6-fold increase in this work and 3.5 and 4-fold for the estrus; Mehdid et al, 2013;Moroni et al, 2007). The fact that all the TEscc in the STR group were concentrated on day 1 suggests that they were caused by the stress suffered by the animals on day 0.…”

“…Moreover, the SCC in goats has demonstrated high daily variability (Randy et al, 1988;Zeng et al, 1997), showing notable transient elevations of SCC lasting 1-3 days, in which the SCC increased 2-20 times within a day. Estrus has been shown to raise the SCC in goats (Christodoulopoulos et al, 2008;McDougall and Voermans, 2002;Moroni et al, 2007) and originate transient elevations of SCC which cannot be explained by variations in milk production (Mehdid et al, 2013). However, whether there are other non-infection factors that can also cause these SCC rises in goats remains unknown.…”

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

“…When the bacteriological analysis was negative and SCC was > 1 000 000 cells/ml on two or more consecutive sampling days and for non-physiological causes, it was considered unspecific (UNS). A physiological increase in SCC, for example due to oestrus (Christodoulopoulos et al 2008) or acute stress (Mehdid et al 2013) was defined when bacteriological analysis was negative and there was an increase of SCC in both glands for a maximum of 3 consecutive sampling days which was followed by SCC < 1 000 000 cells/ml in a subsequent analysis. A gland was considered free from mastitis with negative bacterial culture and SCC < 1 000 000 cells/ml or if the increase of SCC values was due to physiological causes.…”

Performance of current microbial tests for screening antibiotics in sheep and goat milk

“…Moreover, sheep and goat milk is characterised by a higher fat and protein content than cow milk (Park, Juarez, Ramos, & Haenlein, 2007), an elevated natural inhibitor content (e.g., immunoglobulins, lactoferrin, or lysozyme) (Crosson, Thomas, & Rossi, 2010) and a higher somatic cell count (SCC) even in the absence of intramammary infections (Medhid, Díaz, Martí, Vidal, & Peris, 2013), potentially interfering in the microbial inhibitor test response.…”