Metabolismo Minerale della Bovina da Latte in Transizione: Impatto sull'Efficienza Riproduttiva

Abstract

Macro and micro minerals play a vital role in preventing metabolic disorders around calving, particularly milk fever (MF), retained fetal membranes, mastitis and lameness. These condition all have a negative impact on ovulation and cow fertility and, therefore, their prevention offers potential improvements to fertility later in cows. In particularly the control of four macromineral intake is important in preventive MF, which is, unfortunately, often associated with parturition in cows (Ca, P, Mg, and K). An alternative approach is to provide dietary guidelines for minerals that will result in a reasonable DCAD (or dietary cation anion difference). The purpose of the first experiment was to evaluate the influence of Ca and Pi levels during transition period on reproductive efficiency in dairy cows fed with two close-up rations with different DCAD. One group was fed a basic close up diet added with anionic salts daily (DCAD = 0 meq); the other group was fed a basic diet without the addition. Anionic salts treated cows showed transition lower calcium level, higher phosphorous level than untreated cows. Treated cows had better reproductive performances, even if they had lower total calcium levels than untreated animals. These results suggest that the use of anionic salts during close-up period can improve reproductive performance of dairy cattle and according to other authors, the level of calcium in the ration should be increased proportionally to DCAD reduction. The second experiment investigates about the influence of several macromineral serum levels during transition period on puerperal diseases and reproductive performances in high-producing dairy cows. Among the macro-minerals considered, Ca, Mg e Pi serum levels were particularly interesting. Healthy cows had significantly fewer days to first artificial insemination and days open than ill ones. These results suggest that peripartum macromineral serum levels can influence the incidence of post-partum diseases and affect reproductive performances in dairy cows. The third experiment evaluates the relationship between Se, Zn, Cu serum levels around calving and the incidence of Retained Fetal Membranes (RFM) in dairy cows. Se serum levels of cows with RFM were not significantly different from cows without RFM, while Cu and Zn serum levels showed a tendency to be lower than untreated healthy cows. Based on these results we can suggest that Cu and Zn could play an important role in determining RFM; more investigations are probably necessary to clarify the effects of these micro minerals on cows reproductive efficiency. For successful transition from the dry period to lactation it is important to maintain a correct macro and micro mineral intake pre- and post-calving by using correctly balanced and integrated rations.