Milk yield, milk composition and blood metabolites in organic sows on pasture winter and summer - effect of two different dietary protein levels

Summary

Normal and low protein level was tested in 47 organic 1st and 2nd parity sows in summer and winter under Danish weather conditions. There were no differences between the two dietary regimens on milk yield, milk composition or blood metabolites (P>0.05). In contrast, sow performance was higher during summer than in winter (P<0.001).Casein concentration was greater (P=0.01) and protein concentrations tended to be higher (P=0.10) in milk from sows fed with NP diet than the LP diet. In conclusion, a 13% lower protein level did not impair sow performance, milk composition or blood metabolites, when sows were fed iso-energetic (ME) concentrate and had ad libitum access to fresh clover grass during summer and grass silage during winter.