In recent years, the use of both natural and synthetic zeolites in livestock feeds fed to lactating cows has increased, mainly to improve their performance, health, and to protect against mycotoxins intoxication. Data of scientific literature were compiled to analyze the effects of the incorporation of non-nutritional adsorbent zeolite on production performance and ruminal environment parameters of lactating cows. At moderate levels (200–400 g/cow/day), milk yield was increased by zeolite. Milk fat and protein contents and DMI were not altered and all ruminal parameters were improved: acetate was enhanced, propionate was reduced and consequently, acetate to propionate ratio was increased. The rumen pH was increased and rumen ammonia nitrogen was reduced. When the level of zeolite exceeded 400 g/d/cow, all production and ruminal parameters were negatively altered. These data suggest that zeolite level in the diet has a significant effect on the response of dairy production and ruminal environment characteristics.

The objective of the article was to analyze the influence of psychrotrophic bacteria counts (PBCs) and somatic cell counts (SCCs) on the extent of lipolysis in bulk samples of cow's milk at reception and during cold storage. Samples of milk were analyzed on the day of sampling and subsequently during cold storage. The acidity, fat, density, chloride content, electrical conductivity (EC), bulk milk SCCs (BMSCC), and PBC values were analyzed on the day of sampling and the levels of acidity, EC, SCC, and PBC were analyzed during cold storage at 4 °C for 72 h. The SCC value 869 × 10(3) mL(-1) was higher than the recommended threshold. Lipolysis level at sampling day was related more closely with SCC than with PBC. There was no significant correlation between milk acidity and PBC among others parameters, while the milk mean density was only significant (P < 0.01) correlated with the fat content. The EC and chloride content were consistently correlated (P < 0.001) with BMSCC that allowed them to be used as indicators of mammary gland infection. The milk acidity, EC, PBC, and lipolysis levels increased in relation to the storage time at 4 °C. The lipolysis level during storage was in closer relation to the SCC, but not relation to the PBC. Effects of SCC and PBC on lipolysis decreased throughout the chilling period. It was concluded that initial lipolysis level and intrinsic milk lipoprotein lipase appear more effective than SCC and PBC on the development of lipolysis during storage.

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In the present study, the relationship between total bulk milk somatic cell counts (BMSCC), differential BMSCC (macrophage, lymphocyte, and polymorphonuclear leukocytes), and antioxidant enzymes was investigated. Forty-three samples of bulk milk were selected randomly from eight dairy farms in the region of Sfax (Tunisia) in winter, from November 2005 to February 2006. Bulk milk samples were analyzed for antioxidant enzymes such as catalase, SOD and GSHPx activity and differential SCC. After that, milks were allotted according to their total SCC to: group 1, bulk milk with SCC below 1000 × 10 3 ml −1 ; group 2, bulk milk with SCC from 1000 × 10 3 to 1500 × 10 3 ml −1 ; group 3, bulk milk with SCC above 1500 × 10 3 ml −1 . BMSCC levels ranged from 400 × 10 3 to nearly 4000 × 10 3 ml −1 . Lymphocytes were the predominant cell type in all groups, but their proportion declined with the total BMSCC. Catalase and GSHPx activities were found to be significantly (P < 0.001) correlated with total BMSCC and with the PMN population. In contrast, a weak correlation between the activity of the SOD and total or differential bulk milk somatic cells was observed. It has been suggested that milk cells, especially PMN, could generate a situation of oxidative stress in the mammary gland. Specifically, hydrogen peroxide and hydroxyl radicals were probably the most important reactive oxygen metabolites released by PMN.

The purpose of this study was to determine effects of inclusion of Zeolite in lactating dairy cows' rations on blood Ca, P, and Mg status during periparturient period, as well as on milk yield and composition during early lactation. Forty-two pregnant dry Holstein cows were randomly assigned as Zeolite treated cows (EG) or untreated cows (CG) comprising 21 cows each. The EG group received the same diet as the CG group, but with addition of 200 g/cow/day of Zeolite. There was no treatment effect on milk total solids, milk fat, milk protein, lactose, milk ash, milk Ca, milk P, milk Mg, plasma P, and plasma Mg for CG and EG. Conversely, milk yield, fat corrected milk (FCM), fat yield, protein yield, lactose yield, and plasma Ca were significantly increased by Zeolite addition. These results indicate that Zeolite can be effectively used in the rations of dry and lactating cows with positive effects on milk production and components yields and no deleterious effects on milk composition or blood parameters. Blood Ca was enhanced around calving and at the beginning of lactation. It is suggested that prepartum Zeolite supplementation may alleviate the negative Ca balance and therefore reduce the incidence of subclinical hypocalcaemia during the periparturient period.