Feeding anionic salts for preventing partorient paresis; The DCAD-Concept and its effects on health status of dairy cows and their calves | Die Verfütterung Saurer Salze zur verhinderung von Gebärparese

Feeding diets with negative dietary cation-anion difference (DCAD) to dry cows is a common method to prevent parturient paresis. Administration of anionic salts leads to metabolic acidosis, which is usually compensated for by adult animals without clinical signs. On the other hand balance of acid-base status of newborn calves is very unstable. External influences like dystocia, aspiration of amniotic fluid, respiratory diseases and especially diarrhoea may cause fatal metabolic acidosis in newborn calves. There is very poor scientific evidence suggesting that calves born to cows supplemented with anionic salts have metabolic acidosis or not. In our trial, 36 multiparous dairy cows were allocated to three groups (n=12). Cows of group 0 served as a negative control (ration DCAD=230 meq/kg DM), animals of group I received 150 g/d anionic salts (ration DCAD=102 meq/kg DM) and cows of group II received 300 g/d anionic salts (ration DCAD=-7 meq/kg DM), beginning 3 weeks prior date of parturition, respectively. In this study a commercially available product containing anionic salts was used (DCAD=-8000 meq/kg). Mineral nutrients, trace elements and vitamins were supplemented according to supply of cows from group II (ration content per kg DM: Ca=80 g; P=50 g; Mg=60 g; Na=18 g; K=240 g; Cl and S differed between groups in accordance to anionic supplementation). Examinations conducted in cows: dry matter intake (DMI/d), blood and blood gas analysis, urine analysis. Examinations conducted in calves: APGAR-Score (vitality), blood and blood gas analysis (pursued a scheme:15 blood gas analyses within the first 72 hours of life). Statistical evaluation (ANOVA) showed that DMI of cows (mean 12.4 kg/d) did not differ significantly between groups. Contents of blood Ca++ (ionised blood Ca) of cows were 1.23 mmol/l (0), 1.24 mmol/l (I) and 1.22 mmol/l (II) and also blood pH did not differ significantly between groups (p0.05). The lack of significant differences can be seen as a consequence of high K contents in the ration and because of inadequate acidification. On the other hand net acid-base excretion (NSBA) was 118 mmol/l (0), 69 mmol/l (I) and 53 mmol/l, respectively (p0.05). pH in urine was 8.47 (0), 8.42 (I) and 8.19 (II) (p0.05). Blood pH mean values from the first blood samples, taken within the first 30 minutes after birth of calves, were 7.35 (0), 7.29 (I) and 7.24 (II), respectively (p0.05). Lapse of blood pH in calves of group I and group II took 10-14 hours to achieve the level of blood pH of calves in the control group (pH 7.39). These results indicate that calves born to cows supplemented with anionic salts do have significant lower blood pH during first hours of their life.