Effect of altitude and size of livestock farms on productive and reproductive aspects in the south-western region of Norte de Santander

To evaluate milk production (LP), daily gain of weight in calves (GDP), interval between births (IEP) and use of artificial insemination in Cacota, Chitagá, Pamplona, Pamplonita, Silos, and Mutiscua, a sample of farms was selected (n=113) and a direct survey was applied. Two sizes of farms were characterized: up to 10 animals (47.8%) and >10 animals (52.2%). The farms were grouped by quartiles of altitude in meters above sea level (MSNM) (Q1: 1600-2300 (n=27), Q2: 2300-2600 (n=28), Q3: 2600-2800 (n=28), Q4: 2800-3800 (n=30). The Normande race predominates (38.2%), followed by Holstein (23.0%). The presence of Normande decreases with altitude descent, being different between Q4 and Q1 (P=0.009). Genotypes of Cebuins (Gyr, Brahman) appear in Q2 and increase in Q1 (P=0.03). The PL was 5.5±0.2 L/cow*day, with higher productions in Chitagá and Mutiscua (6.4±0.6 and 6.1±0.4 L/cow*day respectively), and lower (P=0.005) in Pamplonita 4.4±0.4 L/cow*day. The GDP was 367±17 g/day, and tended to be lower (P = 0.09) in farms with up to 10 animals (336±23.3 g/day, n=46) compared to farms with more than 10 animals (393±23.7 g/day, n=53). The larger farms (>10 animals) had a lower average IEP with 393±5.5 days (n=59), compared to farms with up to 10 animals (419±11.4 days, n=54; P= 0.04). For quartile Q1, the IEP was higher (438 days, P = 0.01) than Q4 (382 days). The use of semen from nine breeds for artificial insemination was reported, 48.8% corresponding to specialized dairy breeds (Jersey 27.9%, Ayrshire 11.6%, and Holstein 9.3%), 30.2% dual purpose European breeds (Normandy 27.9%, Simmental 2.3%), and 21.0% zebuin breeds or their crosses (Gyr 11.7%, Guzera 4.7%, Girolando 2.3%, and Brahman 2.3%). The present characterization allows us to diagnose the current state of the livestock industry in the region studied and to project technical guidelines for improvement