A cow type for concentrate-free feeding systems - What characteristics does it display?

Summary

Feeding of concentrates to ruminants in organic farming in Switzerland is questionable due to several aspects: (i) suitability for ruminants, (ii) land use change caused by soy cultivation, (ii) organic principles of closed circuits, and (iv) ethical considerations when ruminants directly compete with human nutrition.
In the past decades breeding strategies in the dairy sector focused primarily on milk production which led to increased energy requirements. A reduction of concentrates in the ration may thus lead to a more negative energy balance and may be detrimental for health and fertility. Published genotype x feeding system interactions suggest that different breeds, strains or genotypes react differently to different levels of feeding. The aim of this study was to analyze potential auxiliary traits for their relationship with health and fertility in order to find typical traits for cows that remain healthy and fertile under concentrate-free feeding conditions. The study was carried out as part of the “Feed no Food”-project at FiBL.
Physical parameters of interest were type traits related to body size and volumetric dimensions, BCS and milk components. Type traits were corrected for breed. Parameters for health and fertility were calving interval, somatic cell score (SCS), treatment incidences, and lameness score for a subset of animals. Data from totally 159 dairy cows on 14 organic farms were available. Generalized linear mixed effects models with health and fertility parameters as outcome variables were calculated for this data set. Feeding behaviour was measured using a pressure sensor developed at ART in Tänikon. 26 cows on one farm were equipped with this sensor attached to a halter for three times 24 hours in September and December each. Behavioural parameters were analyzed through correlations and linear regression for individual patterns and influence of stage of lactation. Relationships among behavioural, physical, health, and fertility parameters were evaluated through spearman correlations.
A larger BCS range within one lactation was found to be associated to prolonged calving intervals and more fertility and total treatment incidences. Fat-to-protein ratio (FPR) values of above 1.5 also indicated longer calving intervals but reduced SCS. Both, BCS range and FPR of above 1.5, are well known in literature as predictors of certain health and fertility disorders. Due to their considerable heritability, both traits have potential to be used in breeding strategies for concentrate-free feeding systems. Yet, the connection between FPR and SCS was unexpected and might be caused by decreasing milk yields as consequence of udder inflammation and thus a less negative energy balance. Contrary to the prevailing view, smaller cows (height at the withers) were associated with slightly more treatment incidences. Cows in higher lactations showed impaired health (SCS) and fertility (calving interval).
Values for traits related to feed intake (feeding duration, mastications while feeding) as well as number of boli produced, mastications per boli, rumination and feeding rate (mastications/min) revealed individual patterns when comparing the two measurement periods. No influence of stage of lactation was found. Rumination duration and mastications per bolus were not as individually consistent between the two measuring periods and they were partly influenced by stage of lactation. Except for single correlations between behavioural traits and lameness, no relationship between feeding behaviour and health or fertility parameters could be found.
The individual pattern of some of the behavioural traits might to a certain degree be due to genetic determination. Further investigations with more animals are necessary to detect any potential connections to health or fertility and to assess heritability. Advanced instruments to measure chewing activity in cows are currently being tested and could possibly simplify large-scale observations.