Factors affecting somatic cell count in dairy goats: a review

Abstract

Somatic cell count (SCC) in monitoring udder health has been described in numerous studies as a useful method for the diagnosis of intramammary infection (IMI), and it is considered in standards of quality and hygiene of cow's milk in many countries. However, several authors have questioned the validity of SCC as a reliable IMI diagnosis tool in dairy goats. This review attempts to reflect the importance of different infectious and non-infectious factors that can modify SCC values in goat milk, and must, therefore, be taken into account when using the SCC as a tool in the improvement of udder health and the quality of milk in this species. In dairy goats, some investigations have shown that mammary bacterial infections are a major cause of increased SCC and loss of production. In goats however, the relationship between bacterial infections and SCC values is not as simple as in dairy cattle, since non-infectious factors also have a big impact on SCC. Intrinsic factors are those that depend directly on the animal: time and number of lactation (higher SCC late in lactation and in aged goats), prolificity (higher SCC in multiple births), milking time (higher SCC in evening compared to morning milking) and number of milkings per day, among others. Extrinsic factors include: milking routine (lower SCC in machine than in manual milking), seasonality and food. In addition, milk secretion in goats is mostly apocrine and therefore characterized by the presence of epithelial debris or cytoplasmic particles, which makes the use of DNA specific counters mandatory. All this information is of interest in order to correctly interpret the SCC in goat milk and to establish differential SCC standards.Additional key words: infectious and non-infectious factors; milk quality; mastitis; benchmarking.

Invited review: Animal-based indicators for on-farm welfare assessment for dairy goats

“…In dairy animals, SCC is an important milk characteristic possibly related to animal welfare. Research in dairy goats suggests that this indicator is related to intramammary infections, as SCC increases in presence of clinical or subclinical mastitis Koop et al, 2012), although the latter is asymptomatic and is not reported to affect goat welfare (Jimenez-Granado et al, 2014). Somatic cell count is routinely collected herd data on bulk milk; therefore, it is available in most farms.…”

Divergent selection on milk somatic cell count in goats improves udder health and milk quality with no effect on nematode resistance

“…Milk SCC in goats is commonly higher than in cattle and sheep (Contreras et al, 2007). Furthermore, the ability of milk SCC to predict IMI may be lower in goats than in cattle and sheep, as many environmental factors can increase SCC in the uninfected halves (Poutrel and Lerondelle, 1983;Boettcher et al, 2005;Contreras et al, 2007;Jiménez-Granado et al, 2014). This has raised the question of whether milk SCC is an efficient selection criterion for reducing IMI.…”

Genetic Parameters for Somatic Cell Count, Logscc and Somatic Cell Score of Breeds: Improved Valachian, Tsigai, Lacaune and their Crosses/Genetski Parametri Za Broj Somatskih Ćelija, Logscc I Skor Somatskih Ćelija Kod Rasa: Poboljšana Vlaška, Cigaja, Lakon I Njihovih Meleza

“…Somatic cell count is also included in the parameters considered for the determination of milk price in several European countries [27]. Mastitis is one of the major diseases which leads to signifi cant economic losses mainly due to discarded milk, decreased milk production, quality, early culling, and increased health care costs in dairy ewes [28][29][30][31][32][33][34][35][36][37], cows [38][39][40][41][42] and goats [43][44][45][46][47]. Studies on the genetic resistance to mastitis have increased recently, showing the economic importance of this trait [48].…”