Alen Dzidic

Validation of simulation model for robotic milking barn design

Abstract As milking robots are a recent technological development, there are few precedents and little experience to draw upon when designing robotic milking barns. There is wide diversity among farms, so the optimal layout of the robotic milking barn (RMB) varies accordingly. Using a behaviour-based simulation model, the design focused on optimal facility allocation and its relation with feeding routine, herd size, management practices, etc. This paper applies validation study, compares data on real and simulated RMBs. Measurements from a real robotic farm with 10, 20, and 29 cows are compared with simulation data. The simulation model appears to be a valid, accurate representation of the real system, under commercially feasible conditions. This hypothesis is tested statistically and is not rejected at α =2.5%. So, the conclusion is that the model is a practical design tool, enabling the designer to optimise facility allocation and barn layout.

Oxytocin release, milk ejection and milking characteristics in a single stall automatic milking system

The objective of this study was to evaluate the effect of teat cleaning by two rolling brushes on oxytocin (OT) release, milk ejection and milking characteristics during milking in a single stall automatic milking system (AMS). Five treatments B0 (no brushing), B1 (one brushing cycle for 16 s, 4 s per teat), B2, B4 and B6 (two, four and six brushing cycles, respectively) were randomly changed and quarter milk flow curves were recorded. In addition, blood samples were taken from 10 randomly selected cows during milking at 1-min intervals for OT determination in treatments B0, B2, B4 and B6. Basal OT concentrations were similar (2.7 to 3.9 pg/ml) in all treatments. At the start of milking, OT concentration was lower (P<0.05) in B0 as compared to all other treatments. At 1 min after the start of milking and throughout milking OT concentrations did not differ between treatments. Time until occurrence of main milk flow was lower in well filled udders as compared to udders with small amounts of milk stored. Frequency of the bimodal curves is decreasing with increasing number of brushing cycles. The teat cleaning device in the used AMS was suitable to induce OT release and milk ejection before the start of milking in treatments B2, B4 and B6.

Effect of stimulation intensity on oxytocin release before, during and after machine milking

Release of oxytocin (OT) is essential for milk ejection in dairy cows (Lefcourt & Akers, 1983 ; Bruckmaier & Blum, 1998). During milk ejection, alveolar milk is shifted into the cistern, which causes an increase of intracisternal pressure (Bruckmaier et al. 1994). To initiate maximum milk ejection at the start of milking, increasing OT concentration beyond a threshold level is sufficient (Schams et al. 1983). Increasing OT concentration beyond this threshold has no additional effect on intracisternal pressure, i.e., milk ejection (Bruckmaier et al. 1994). Stimulatory effects of milking by hand or by machine or by suckling are well documented (Gorewit et al. 1992 ; Bar-Peled et al. 1995 ; Tancin et al. 1995 ; Bruckmaier & Blum, 1996). At the start of milking, stimulatory effects of machine milking without pre-stimulation or with a manual pre-stimulation and subsequent machine milking cause the release of comparable amounts of OT (Gorewit & Gassman, 1985 ; Mayer et al. 1985 ; Bruckmaier & Blum, 1996), whereas the timing of the applied pre-stimulation is important for the shape of the milk flow curve. Should the pre-stimulation period be too short, or absent altogether, the start of the main milk flow is delayed resulting in a bimodal milk flow profile (Bruckmaier & Blum, 1996). Furthermore, the stimulation of only one teat causes an OT release similar to that caused by stimulation of all four teats (Bruckmaier et al. 2001). However, milk production is greater for hand milking or suckling than for machine milking, possibly owing to higher OT concentrations (Gorewit et al. 1992 ; Bar-Peled et al. 1995).

Genetic diversity and differentiation of 12 eastern Adriatic and western Dinaric native sheep breeds using microsatellites

Nuclear genetic diversity and differentiation of 341 sheep belonging to 12 sheep breeds from Croatia and Bosnia and Herzegovina were examined. The aim of the study was to provide the understanding of the genetic structure and variability of the analysed pramenka sheep populations, and to give indications for conservation strategies based on the population diversity and structure information. The genetic variation of the sheep populations, examined at the nuclear level using 27 microsatellite loci, revealed considerable levels of genetic diversity, similar to the diversity found in other European indigenous low-production sheep breeds. Population-specific alleles were detected at most loci and in breeds analysed. The observed heterozygosity ranged from 0.643 (in Lika pramenka) to 0.743 (in Vlasic pramenka), and the expected heterozygosity ranged from 0.646 (in Lika pramenka) to 0.756 (in Dalmatian pramenka). Significant inbreeding coefficients were found for half of the populations studied and ranged from 0.040 (Pag island sheep) to 0.091 (Kupres pramenka). Moderate genetic differentiation was found between the studied sheep populations. The total genetic variability observed between different populations was 5.29%, whereas 94.71% of the variation was found within populations. Cres island sheep, Lika pramenka and Istrian sheep were identified as the most distinct populations, which was confirmed by the factorial analysis of correspondence and supported through a bootstrapping adjustment to correct for the difference in the sample sizes. The population structure analysis distinguished 12 clusters for the 12 sheep breeds analysed. However, the cluster differentiation was low for Dalmatian, Vlasic, Stolac and Krk pramenka. This systematic study identified Lika pramenka and Rab island sheep as those with the lowest diversity, whereas Istrian sheep and Pag island sheep had the highest. Conservation actions are proposed for Istrian, Rab and Cres island sheep, Lika and Kupres pramenka because of high estimated coefficients of inbreeding.

Relationship between udder and milking traits during lactation in Istrian dairy crossbreed ewes

Abstract The aim of this study was to determine the udder morphology and milking characteristics changes throughout lactation during machine milking of the sheep. Additionally, udder morphology was analyzed by using slide ruler and digital picture. Milking characteristics were influenced by milking interval and day of lactation. Udder morphology traits did not change throughout lactation, except for udder width. The repeatability between slide ruler and digital picture measurements was high (r=0.53 to 0.68). Milkability in Istrian dairy crossbreed ewes could be improved if udder traits are incorporated in selection scheme. Digital picture analysis for faster recording of udder morphology measurements in sheep can be used.

Sequence polymorphism of PrP exon 3 gene in Istrian and crossbred sheep

Abstract Polymorphisms in sheep PrP (prion protein) gene are known for scrapie susceptibility. We sequenced part of PrP exon 3 gene in 92 autochthonous Istrian (IS) and 38 crossbred sheep (CBS). ARQ, ARR and AHQ alleles were predominant with frequency of 0.674 (0.526), 0.228 (0.132) and 0.082 (0.263) in IS (CBS), respectively, while VRQ (0.011 in IS) and ARH (0.005 in IS and 0.079 in CBS) alleles were rare. We also found non-synonymous mutations at codons 112 (M→T), 127 (G→S) and 143 (H→R), and synonymous mutations at codons 231 (R) and 237 (L). Additional mutations were associated only with AHQ, ARH and ARQ alleles. The polymorphism of PrP gene in IS was not critical with respect to scrapie susceptibility and with some efforts number of “favourable” genotypes can be increased.