Changes in milk composition of sows during 28 days of lactation

Our trial was aimed at finding daily nutrient and milk production during 28 days of lactation. Daily production of protein, fat, ash and nitrogen free extract (NFE) was determined. The results can be described by regression equations for daily (x) production of fat (g/day) = -0.5735x(2) + 25.009x + 273.14 (R-2 = 0.9209), protein (g/day) = 0.0497x(2) - 2.3482x(2) + 30.882x + 247.72 (R-2= 0.6896), NFE (g/day) =-0.6166x(2)+ 29.463x + 129.58 (R-2 = 0.9857) and ash (g/day) = -0.121x(2)+ 5.4817x + 32.781 (R-2= 0.9749). The mathematical expression of daily milk production in kg = 0.0004x(3) - 0.026x(2) + 0.6401x + 2.799 (R-2= 0.9949), where x = day of lactation. Other interesting results are the average dry matter of milk 184.31 g/kg, that of protein 50.76 g/kg, fat 68.45 g/kg, NFE 5 797 g/kg and ash 14.12 g/kg. I kg milk contained 4.82 MJ energy on average.