Behavior of the productive, reproductive and metabolic parameters of meat cows with an organic management. Technical note

The current study describes productive, reproductive and metabolic performances reached by beef cattle under organic and conventional management. The experiment was carried out in two farms in La Araucania Region, Chile. Both farms provided six cows and one bull for copulation. The feeding offered to conventional animals was based on a grassland of Lolium perenne with Avena sativa supplemented with hay and oat silage; feed produced with synthetic fertilizers. In addition, the animals are handled in a conventional way, that is, with the periosic application of antiparasitic agents, vaccines, vitamins and traditional veterinary drugs. The organic animals were offered natural organic grasslands with Lolium perenne, Trifolium repens, Holcus lanatus, Paspalum dilatatum, Lotus pedunculatus, Dactylis glomerata and were supplemented with hay of the same composition; feed produced without addition of any agrochemicals and fertilized only with manure. In addition, the animals were handled without the application of any traditional veterinary drug, using only phytotherapy and homeopathy as treatments of choice in case of pathologies.. The study period started one w before calving and finished on the eighth w postpartum. Blood samples and weight measurements were taken once a week (w). After the third w postpartum, the bull returned to the herd and cows had an echography each w to determine the return to their estrous cycle. At the beginning, organic cows body condition and weight scores increased throughout the experiment reaching an average weight of 408 ± 44.6 kg, and weighing 481 ± 58.8 kg at the end. Whereas, conventional cows did not exhibit the same tendency at the beginning, throughout the study they lost weight due to low food offering (966 kg dry matter (DM/ha) v/s 1670 kg DM/ha). This is a strategy used by conventional farmers to recover body condition score faster, which when combined with a Negative Energetic Balance (NEB) in the peripartum period, lead to a decrease in livestock weight. When conventional cows gave birth, non esterified fatty acids (NEFAS) and β hidroxy butyrate (βHB) concentrations in blood increased greatly, showing significant differences (P < 0.05) compared to organic cows, even in the first w, which presented lower concentration levels during the experiment. However, these levels decreased in the conventional group, when food offer increased (1417 Kg DM/ha), almost matching the two groups on the same level. In regards to reproductive aspects, significant differences were found in luteal tissue apparition between both groups (P < 0.05) in postpartum anestrus. On average, organic cows returned to cyclicity 1 w before conventional cows. In conclusion, the differences observed between both farms are not attributed to a difference in organic or conventional management but rather to feeding management differences.