Effect of two winter housing systems on production, body weight, somatic cell count, BCS, and dry matter intake of organic dairy cows

Abstract Text: Organic cows (n = 83) were used to evaluate the effect of 2 winter housing systems (December 2012 to May 2013) on production, SCC, body weight, BCS, and DMI. Cows were assigned to 1 of 2 treatments (2 replicates per group): 1) outdoor (straw pack, n = 42) or 2) indoor (compost-bedded pack barn, n = 41). There were 21 cows per replicate for the outdoor housing and 21 and 20 cows per replicate for the indoor housing.  Cows calved during 2 seasons (March to May 2012 and September to December 2012) at the University of Minnesota West Central Research and Outreach Center, Morris, Minnesota, organic dairy. Organic wheat straw was used as bedding for the 2 outdoor bedded packs, which were 12 m wide by 27 m long, and maintained by farm management to keep cows dry and absorb manure throughout the winter.    The open-front compost-bedded pack barn (2 pens in the barn) was bedded with organic approved sawdust, and the bedding material was stirred twice per day with a small chisel plow. Cows were fed a TMR that included organic corn silage, alfalfa silage, corn, expelled soybean meal, vitamins and minerals.  Milk, fat and protein production and SCC were recorded from monthly DHIA testing. Body weight and BCS were recorded bi-weekly as cows exited the milking parlor. The PROC MIXED of SAS was used for statistical analysis, and independent variables were fixed effects of season of calving (fall or spring), parity (1, 2, 3+), breed group, housing system, with replicate and cow nested within the interaction of housing system and season as a random effect. Energy-corrected milk and SCC was not different for the outdoor (15.5 kg/d, 206,000 ml) and indoor (16.1 kg/d, 357,000 ml) housing systems, respectively.  In addition, outdoor and indoor housing systems were not different for body weight (523 vs. 538 kg) and BCS (3.15 vs. 3.08), respectively. Daily DMI was 17.8 kg/d for indoor cows and 17.6 kg/d for the outdoor cows (P = 0.47).  Total bedding costs during the winter was $8,275 for the outdoor system and $9,248 for the indoor system.  In summary, cows housed outdoors on straw-bedded packs did not differ from cows housed in an indoor compost-bedded pack barn for production and SCC, as well as body weight, BCS, or DMI.

Keywords:

organic, outwintering, compost barn