Small Ruminant Research 122 (2014) 1–3
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Editorial
Selected lectures from the Regional IGA Conference on Goat Milk Quality, Tromsø, Norway, June 4–6, 2013: From the Editor bird-eye
It was a pleasure to serve as the guest Editor of the Regional International Goat Association (IGA) Conference on Goat Milk Quality, which took place in Tromsø, Norway June 4–6, 2013. Two wishes motivated an international conference on goats in Norway. One was to welcome experts on goats to a regional IGA conference in Norway, and the second was to finalize a national scientific research project with a conference on goat milk quality. The IGA Board supported the idea. A full scope of the presentations that were presented during the conference is available at the symposium website: http://geithold.no/g2013. The scientific level of the presentations was high and the pleasant and intimate atmosphere that prevailed during the conference promoted interesting discussions. A selection of the lectures chosen to be presented in the frame of this special issue is briefly overviewed. Small Ruminant Research (SRR) is the leading journal that covers peerreviewed scientific investigations on goats and sheep. The journal encircles broad range of research areas. The quality of goat’s milk represents a very important aspect in the section of Lactation and Dairy Technology (products and quality) in SRR, for which I am serving as the Associate Editor. The particular importance of milk quality in the goats industry relates to the fact that in western countries most of the milk is processed into dairy products, particularly a wide range of cheeses. Therefore, the relationship between the selected lectures to topics considered in SRR in the last years is also reflected. Goat production in Norway is unique because it is expended to the arctic region of Norway and therefore represents the northernmost dairy farming in the world. The issue starts with a review that covers the historical role of dairy goats in the Norwegian agriculture and culture and the needs to modernize the industry in order to fit to changes in economy and alteration in demand for goat http://dx.doi.org/10.1016/j.smallrumres.2014.07.010 0921-4488/© 2014 Elsevier B.V. All rights reserved.
cheeses products by consumers (Ådnøy, 2014). The second presentation covers the importance of milk quality for cheese production (Skeie, 2014). Though this review puts emphasis on the Norwegian industry, it gives updated presentation of the general picture. The grazing of pasture by goats represents important aspects of goat farming worldwide. In general, animals grazing pastures produce milk with higher nutritional and healthier qualities than animals producing milk in confinement, even when they are fed high proportion of conserved forage (Morand-Fehr et al., 2007; Silanikove et al., 2010). Among the milk components that contribute to the good health of consumers are fat soluble vitamins and fatty acids with lower atherogenic index and with particular health-promoting benefits (Zervas and Tsiplakou, 2011; Renna et al., 2012; Delgado-Pertinez et al., 2013; Mancilla-Leytón et al., 2013). Small ruminants are the most efficient domestic animals in converting low to medium quality forage into high quality dairy products with remarkable chemical composition and organoleptic characteristics (Zervas and Tsiplakou, 2011). Goats are the most efficient domestic ruminant in utilizing browse sources as food, which enable farmers to exploit efficiently natural resources where no other animals can be raised without intensive supplementation of food (Silanikove et al., 2010). The ability of goats to utilize tannins, the most notable secondary metabolite in browse, was considered as unexploited ‘treasure trove’ (Silanikove et al., 2010). The effect of consumption of food rich in secondary metabolites on various aspects of product quality, including milk, was recently reviewed (Vasta and Luciano, 2011) and a paper describing the positive effects of feeding goats with rosemary (Rosmarinus officinalis spp.) by-product on milk and cheese properties (Boutoial et al., 2013), which represent an example for the benefit from gaining knowledge in this field. As mentioned, the major publications in this area are on the effect of pasture on improvement of fat
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Editorial / Small Ruminant Research 122 (2014) 1–3
composition of milk. The subject was recently reviewed (Zervas and Tsiplakou, 2011) and highlighted by several publications (Renna et al., 2012; Delgado-Pertinez et al., 2013; Mancilla-Leytón et al., 2013). The most consistent and remarkable trends found were increase in the contents of C18:1 t6–11, C18:1 and t11c13 + c9c11 in pasture-fed small ruminants. In goats, the basic high content of medium-chain fatty acids is increased further under pasture-fed conditions. These changes are also associated with increased content of ␣-linolenic and eicosapentaenoic acids. Thus, milk of pasture-fed animals is richer than milk of confined-fed animals in components that are considered beneficial to human health, such as medium-chain fatty acids, conjugated linoleic acid, vaccenic acid (C18:1 t11), rumenic acid (C18:2 c9t11) and omega-3 fatty acids. High content of ␣-linolenic acid in pasture plants was considered as an explanation for this beneficial effect (Renna et al., 2012). However, the editor would like to note that potential interactions between phenolics and fatty acid metabolism on the digestive tract, systemic fluids and mammary gland levels may provide novel explanations for the positive effects of pasture. In addition, recent publications in SRR highlighted the effect of pasture on volatile compound profile of ewe’s milk (Vasta et al., 2012) and effects of variation among individuals, breeds and parities on milk fatty acid profile and milk yield of ewes grazed on pasture (Soják et al., 2013). The third presentation in the special issue relates to pasture utilization and importance of supplementation under Norwegian conditions (Steinshamn et al., 2014). As outlined above, milk fat composition in goats is unique and presents many health promoting advantages over milk fat composition in cows. The dietary and physiological effects on milk fat composition were concisely reviewed by leading researchers and research groups in this area (Chilliard et al., 2014). The presence of conjugated linoleic acids (poly-unsaturated fatty acids that deserve a lot of intention due to its health promoting properties) in ruminants milk results from the isomerization and biohydrogenation of unsaturated fatty acids by rumen bacteria as well as by the activity of Stearoyl-CoA desaturase (Chilliard et al., 2014). The report of Tudisco et al. (2014) in the special issue describes the effect of pasture intake on Stearoyl-CoA desaturase expression on milk somatic cells, which were used as a model for mammary epithelial cell metabolism. In this line, Pikul et al. (2014) reported that supplementation of false flax (Camelina sativa) cake in dairy goat diets increased the concentration of poly-unsaturated fatty acids, including conjugated linoleic acids in their milk and kefir made from that milk. A lot of interest in the scientific literature in recent years is concerned with the effects of polymorphism of milk constituents, particularly those of caseins, on milk quality. The influence of the deletion in exon 12 of the gene encoding ␣s1 -casein was discussed in Ådnøy (2014) and Skeie (2014) reviews and the report of Skeie et al. (2014). Dagnachew and Ådnøy (2014) analyzed the effect of variability in caseins genes on milk yield and composition. The four encoding casein loci, which were CSN1S1 (for ␣s1 -CN), CSN2 (), CSN1S2 (␣s2 ) and CSN3 () had economically important effects on milk production traits.
Mestawet et al. (2014a) presented a short overview, which complete a recent publication on this subject (Mestawet et al., 2014b), on how mutations at the ␣s1 -CN gene in Ethiopian and crossbred goats affect milk quality and how such information may affect selection and breeding strategies in developing countries. Last but not least, Silanikove et al. (2014) stated in their review that sub-clinical mastitis and stage of lactation are the most important factors that affect milk quality for cheese production. The physiological and biochemical basis, which justify this bold statement were extensively reviewed. Suggestions for grading goat milk based on its hygienic properties (somatic cell count) and insights on how future move forward in research and technology may lead to improvement in milk quality were presented. In summary, I hope that the interested reader will find the collection of papers presented in this special issue a valuable source for updated information on factors affecting milk quality in goats. I am confident that SRR will continue to play an important role as an excellent medium for publishing high-quality research in the area of Lactation and Dairy Technology (products and quality) and other topics covered by the journal. References Ådnøy, T., 2014. The dairy goat industry in Norway: challenges in a historical perspective. Small Rumin. Res. 122, 4–9. Boutoial, K., Ferrandini, E., Rovira, S., Garcia, V., Lopez, M.B., 2013. Effect of feeding goats with rosemary (Rosmarinus officinalis spp.) by-product on milk and cheese properties. Small Rumin. Res. 112, 147–153. Chilliard, Y., Toral, P.G., Shingfield, K.J., Roue, J., Leroux, C., Bernard, L., 2014. Effects of diet and physiological factors on milk fat synthesis, milk fat composition and lipolysis in the goat: a short review. Small Rumin. Res. 122, 31–37. Dagnachew, B.S., Ådnøy, T., 2014. Additive and dominance effects of casein haplotypes on milk composition and quality in Norwegian dairy goats. Small Rumin. Res. 122, 59–69. Delgado-Pertinez, M., Gutierrez-Pena, R., Mena, Y., Fernandez-Cabanas, V.M., Laberye, D., 2013. Milk production, fatty acid composition and vitamin E content of Payoya goats according to grazing level in summer on Mediterranean shrublands. Small Rumin. Res. 114, 167–175. ˜ Mancilla-Leytón, J.M., Martín Vicente, A., Delgado-Pertínez, M., 2013. Summer diet selection of dairy goats grazing in a Mediterranean shrubland and the quality of secreted fat. Small Rumin. Res. 113, 437–445. Mestawet, T.A., Girma, A., Ådnøy, T., Devold, T.G., Narvhus, J.A., Vegarud, G.E., 2014a. Crossbreeding, mutations at the ␣s1-CN gene in Ethiopian and crossbred goats: effect on casein content, and coagulation properties of their milks. Small Rumin. Res. 122, 70–75. Mestawet, T.A., Girma, A., Ådnøy, T., Devold, T.G., Narvhus, J.A., Vegarud, G.E., 2014b. New insights in goat breeds of Ethiopia: high content of ␣s1-CN and its association with coagulation properties, whey syneresis and micelle size. Small Rumin. Res. 114, 146–155. Morand-Fehr, P., Fedele, V., Decandia, M., Le Frileux, Y., 2007. Influence of farming and feeding systems on composition and quality of goat and sheep milk. Small Rumin. Res. 68, 20–34. ˙ Pikul, J., Wójtowski, J., Danków, R., Teichert, J.J., Czyzak-Runowska, G., ´ Cais-Sokolinska, D., Cie´slak, A., Szumacher-Strabel, M., Bagnicka, E., 2014. The effect of false flax (Camelina sativa) cake dietary supplementation in dairy goats on fatty acid profile of kefir. Small Rumin. Res. 122, 44–49. Renna, M., Lussiana, C., Cornale, P., Fortina, R., Antonio, M., 2012. Changes in goat milk fatty acids during abrupt transition from indoor to pasture diet. Small Rumin. Res. 108, 12–21. Silanikove, N., Leitner, G., Merin, U., Prosser, C.G., 2010. Recent advances in exploiting goat’s milk: quality, safety and production aspects. Small Rumin. Res. 89, 110–124. Silanikove, N., Merin, U., Leitner, G., 2014. On effects of subclinical mastitis and stage of lactation on milk quality in goats. Small Rumin. Res. 122, 76–82.
Editorial / Small Ruminant Research 122 (2014) 1–3 Skeie, S.B., 2014. Quality aspects of goat milk for cheese production in Norway: a review. Small Rumin. Res. 122, 10–17. Skeie, S.B., Inglingstad, R.A., Brunborg, L.J., Eknæs, M., 2014. The influence of the deletion in exon 12 of the gene encoding CSN1S1 (␣s1-casein) in milk of the Norwegian dairy goat breed on the milk coagulation properties and cheese quality. Small Rumin. Res. 122, 50–58. ´ I., MarSoják, L., Blaˇsko, J., Kubinec, R., Górová, R., Addová, G., Ostrovsky, getín, M., 2013. Variation among individuals, breeds, parities and milk fatty acid profile and milk yield of ewes grazed on pasture. Small Rumin. Res. 109, 173–181. Steinshamn, H., Inglingstad, R.A., Ekeberg, D., Mølmann, J., Jørgensen, M., 2014. Effect of pasture type and season relative to hay diet on dairy goat milk production and quality. Small Rumin. Res. 122, 18–30. Tudisco, R., Grossi, M., Calabrò, S., Cutrignelli, M.S., Musco, N., Addi, L., Infascelli, F., 2014. Influence of pasture on goat milk fatty acids and stearoyl-CoA desaturase expression in milk somatic cells. Small Rumin. Res. 122, 38–43. Vasta, V., Luciano, G., 2011. The effects of dietary consumption of plants secondary compounds on small ruminants’ products quality. Small Rumin. Res. 101, 150–159.
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Vasta, V., D’Alessandro, A.G., Priolo, A., Petrotos, K., Martemucci, G., 2012. Volatile compound profile of ewe’s milk and meat of their suckling lambs in relation to pasture vs. indoor feeding system. Small Rumin. Res. 105, 16–21. Zervas, G., Tsiplakou, E., 2011. The effect of feeding systems on the characteristics of products from small ruminants. Small Rumin. Res. 101, 140–149.
Guest Editor Nissim Silanikove Biology of Lactation Laboratory, Institute of Animal Science, Agricultural Research Organization, P.O. Box 6, Bet Dagan 50 250, Israel E-mail address:
[email protected] Available online 17 July 2014
