Influence of seaweed addition in the dairy goats diet on milk chemical composition

Abstract

The effect of Chlorella pyrenoidosa seaweed inclusion in the dairy goat diet on milk fatty acid composition, atherogenicity index, fat and protein percentage were evaluated in the present study. For the development of the experiment, 10 pregnant goats belonging to Majorera breed were used. The animals were fed with corn, soy 66, dehydrated Lucerne, dehydrated beetroot, wheat straw and vitamin-mineral corrector in accordance with the guidelines issued by L´Institut de Recherche Agronomique. Goats were allotted into two groups (n=6) based on the diet; the control group received a standardized diet (0 g Chlorella pyrenoidosa) and animals of the experimental group (seaweed group) received the standardized diet plus 5 g C.pyrenoidosa from 15 days before partum to day 40 of lactation. Goats were milked by machine milking once a day and milk samples (100 ml) of each goat were collected after milk removal at partum and 1, 2, 3, 4, 5, 10, 20, 30 and 40 days later. Milk samples were divided into two aliquots, 50 ml of each were used to measure the basic chemical composition (fat and protein) immediately after sampling and 50 ml were maintained at -80ºC until fatty acid composition was analyzed. The saturated, polyunsaturated and monounsaturated fatty acids percentage (SFA, PUFA and MUFA) was determined by using a gas chromatograph. The atherogenicity index (AI) was calculated as C12:0 + (4 x C14:0) + C16:0/ MUFA+PUFA. There was no significant effect of seaweed addition on milk fat percentage (8.87 vs 8.70% at partum and 5.20 vs 5.81% at day 40, seaweed and control group, respectively). In addition, fat percentage decreased throughout the experiment in both groups, ranged from 8.87 to 5.20% and 8.70 to and 5.81%, seaweed and control group, respectively. Milk protein percentage decreased throughout the experiment in both groups, ranged from (20.28 to 3.10% and 21.53 to 3.88%, seaweed and control group, respectively) being milk protein significantly higher at first day of lactation in the seaweed group (13.20 vs 8.30%, seaweed and control group, respectively). No significant effects of seaweed diet addition were observed in SFA, MUFA and PUFA percentages and AI. Both groups displayed similar values until day 5 of lactation. However, there was a trend of raising the SFA percentage and AI and decreasing the MUFA and PUFA percentages in both groups from day 10 to day 40 of lactation. In conclusion, the addition of C. pyrenoidosa increases the milk protein percentage at first day of lactation.