Effect of two housing systems on performance and longevity of dairy cows in Northern Italy.

The objective of the current study was to evaluate and compare performance of dairy cows housed in compost-bedded pack barns (CBP) and free stall barns, with a focus on longevityrelated parameters. Study included 30 commercial dairy farms located in the Po Valley, Italy. Twenty farms had free stall barns, among which 10 used rubber mattresses (FSM) and 10 used deep straw bedding (FSS). The remaining 10 farms had CBP. Monthly dairy herd records were obtained from the Italian DHI association for each farm included in the study over a period of one year. All farms were visited to measure characteristics and dimensions of housing facilities. Linear mixed models were used to evaluate the association between housing system and the outcome variables. In CBP total available area was larger than both in FSM and FSS. However, space per cow over the bedded pack area in CBP (6.8 ± 2.4 m2 cow-1) was relatively low for this housing system. Milk production was similar among housing systems but somatic cell count and mastitis infection prevalence resulted to be higher in CBP than in FSM and FSS. Calving interval was lower in FSS compared with both FSM and CBP while no differences were found in number of services per pregnancy. Cows housed in CBP were older and had higher parities than those in FSM and FSS while no significant differences in herd turnover rate were detected among housing systems. Results confirm that CBP housing system may improve longevity of dairy cows, which is reported to be one of the most important motivations for building this kind of housing. Nevertheless, CBP housing can pose some challenges in achieving adequate udder health and high milk quality, especially with low space per cow.