Review: Milking routines and cluster detachment levels in small ruminants.

Small ruminants not only differ on mammary gland anatomy, milk's properties and the amount of milk yielded comparable to those of dairy cattle, but also on the milking routine strategies and machine milking settings to maximize daily milk secretion. The udder compartment is proportionally larger in dairy sheep and goats, which requires modifications in the milking machine settings, milking procedures and allows the use of different milking strategies as they better tolerate extension of milking intervals. Depending on the breed, cisternal milk in goats varies from 70% to 90%, whereas in dairy sheep it varies from 50% to 78% of the total gland capacity. This explains why these species are commonly milked without pre-milking teat preparation, while in goats it is applied only in cases of high prevalence of intramammary infection in the herd. Recent French researchers observed that 40% of the goats presented an unbalanced udder as well as unbalanced morphology (21% to 30%) and functional milk flow (around 10% to 20% more) which could induce overmilking. In dairy sheep, selection for higher milk production increases teat angle insertion. Thus, to increase machine milk fraction, it is recommended to use either the 'Sagi hook' as an alternative for lifting up the 'pendulous' udder during milking or to perform machine stripping. There are three cluster removal strategies for small ruminants: manual, timed and milk flow driven automatic cluster removal (ACR). Automatic cluster removal reduces overmilking, improves teat condition, enables labour saving and provides a consistent milking routine in small ruminants. There are three to five main milk flow profiles in ewes and goats, which result in curves with one or two peaks (or plateau) and different patterns of the milk flow decreasing phase due to the degree of mammary gland imbalance and teat characteristics. When taking into account our current knowledge, ACR recommended take-off settings for goats are: 200 g/min+10 s delay time (DT) for a long decreasing phase or two plateau curves and 500 g/min+5 s DT for a short decreasing phase and one plateau curve. The ACR take-off settings for ewes are: 150 g/min +10 s DT for long decreasing phase and 200 g /min+5 s DT for a short decreasing phase. This review is intended to be useful for scientists and producers seeking basic knowledge of milking routines and cluster detachment settings for parlour performance and milk quality.

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.

Influence of oral application of mycophenolic acid on the clinical health status of sheep.

Mycophenolic acid (MPA) is an immunosuppressive metabolite of various fungi, especially of Penicillium roqueforti, and can be found in considerable amounts in mouldy silage. The aim of this study was to investigate the effect of MPA on sheep. Thirty-six castrated male sheep aged 7 +/- 1 months were randomly divided into four groups of nine sheep. Different dosages of MPA were administered orally to all groups (group 1/2/3/4: 0/10/70/300 mg MPA/animal daily) for a period of 44 days. Throughout the trial, the sheep were examined daily. Jugular vein blood was taken twice weekly to analyse haematological and biochemical parameters. No significant influence was observed on the number of erythrocytes, thrombocytes, leucocytes (including differentiation), packed cell volume, haemoglobin-, glucose- and bilirubin-concentration, activity of alanine amino transferase, aspartate amino transferase and glutamate dehydrogenase. Even an oral application of up to 300 mg MPA/animal daily, which is equivalent to 5.4 mg/kg body weight, did not affect the sheep's general state of health and weight gain significantly. Mycophenolic acid and its glucuronide were analysed in plasma samples of groups treatments from day 1 on with mean concentrations up to 0.29 +/- 0.13 microg/ml (MPA) and 11.0 +/- 2.9 microg/ml (MPA glucuronide) respectively (group 4). There were no indications for a ruminal reduction of MPA. The postmortem dissection revealed minor alterations in lung, spleen, liver and kidneys, unrelated to the MPA dosage. The results of the study indicate that MPA concentrations occurring naturally in silage have no obvious impact on sheep health.

Effects of mycophenolic acid on inosine monophosphate dehydrogenase I and II mRNA expression in white blood cells and various tissues in sheep.

Mycophenolic acid (MPA) is a mycotoxin commonly found as Penicillium genus secondary metabolite in feedstuffs and silages. Feeding with MPA contaminated silages may modulate the immune system in the farm animals and can cause appetite lost, ketosis, paralysis and abortion. The aim of the present study was to characterize the long-term MPA effect on both the inosine monophosphate dehydrogenase (IMPDH) isoforms I and II mRNA expression in white blood cells (WBC) and various tissue of healthy sheep. In treated animals 300 mg MPA/day/sheep was applied. In all investigated tissues the IMPDH I and II mRNA was abundant: WBC, spleen, thymus, ileum, jejunum, kidney, liver, pharyngeal and mesenterial lymph node. An efficiency-corrected relative quantification of the IMPDH types I and II isoforms mRNA were performed by normalizing with the constant reference gene expression of beta-actin. High IMPDH I mRNA expression levels were seen in kidney > mesenterial lymph node > jejunum > spleen > pharyngeal lymph node. Medium and low abundance was found in ileum > WBC > liver > thymus. Type II mRNA was highly expressed in liver > thymus > jejunum. In pharyngeal lymph node > spleen > ileum > mesenterial lymph node > kidney > WBC medium to low IMPDH II mRNA concentrations were detected. Under MPA treatment the IMPDH I mRNA expression was not significantly regulated in WBC, only trends of down- and upregulation were observed. Surprisingly in jejunum an upregulation could be observed (P < 0.05). In pharyngeal lymph node a tendency to downregulation was shown. This may be due to frequent ruminant activities and frequent exposition of MPA to the pharyngeal lymph nodes. In contrast to type I mRNA expression, IMPDH II mRNA was significantly downregulated in ileum (3.4-fold, P < 0.01) and tendencies in downregulation could be seen in jejunum (5.1-fold, P = 0.14). In addition, significant downregulation of IMPDH II gene expression over the entire feeding experiment could be shown in WBC of MPA-treated animals compared with untreated animals (P < 0.05). In conclusion, the recent study demonstrates that feeding sheep with MPA-contaminated silage did not induce IMPDH I mRNA expression in various tissues and blood, except in jejunum, but has suppressive effects on IMPDH II mRNA expression in WBC and ileum.

Effects of cleaning duration and water temperature on oxytocin release and milk removal in an automatic milking system.

Four different methods of teat preparation during milking in an automatic milking system were studied in 2 experiments on Red Holstein/German Fleckvieh cross-breed cows. Milking routines used were milking: 1) without premilking teat preparation; 2) with one cleaning cycle (58 to 60 s) with cold (13 to 15 degrees C) water; 3) with one cleaning cycle with warm water (30 to 32 degrees C); or 4) with 2 cleaning cycles (122 s) with warm water. In experiment 1, milking characteristics were evaluated and milking routines were randomly assigned to 62 cows during 3 measuring periods of 24 h each. In experiment 2, 10 randomly selected cows were assigned to the same milking routines during 4 d and blood samples for oxytocin (OT) determination were taken during milking in addition to milk flow recording. Milk production, peak flow rate, total, and quarter milk yields showed no differences among treatments. Premilking preparation with cold water compared with warm water showed no differences in OT release, milk yield, peak flow rate, main milking time, average flow rate, or time until main milk flow. Baseline OT concentrations were consistently low. At the start of teat cup attachment without premilking teat preparation OT concentrations remained on the basal level but were elevated in all other treatments. By 30 s from the start of milking, OT concentrations were markedly increased in all treatments and were no longer different between treatments. In conclusion, the teat cleaning device used in the automatic milking system, either with warm or cold water, was suitable to induce milk ejection in cows before the start of milking.

Coping capacity of dairy cows during the change from conventional to automatic milking.

In conventional milking systems, dairy cows are driven to the milking stall twice or thrice daily, whereas in automatic milking systems (AMS), the cows enter the milking stall voluntarily. In this study, noninvasive methods were used to analyze the physiological reaction of 17 cows toward the changeover from conventional to automatic milking. Milk yield and composition were analyzed. Heart rate was recorded continuously, and feces was sampled twice daily to determine cortisol metabolites (11, 17-dioxoandrostanes) for a period of 2 wk. During the first visit to the AMS (without milking), heart rate was elevated compared with parlor milking by 35 +/- 3 beats per minute (bpm) above basal heart rate (P < 0.05). Heart rate during the first milking in AMS (eighth visit) was already similar to the heart rate previously measured during milking in the parlor (18.1 +/- 2.2 bpm above basal level). Concentration of fecal cortisol metabolites was unchanged during the change-over compared with parlor milking. A decreased (P < 0.05) milk yield of 68 +/- 7% relative to previous parlor yield during the first AMS milking indicated a disturbance of milk ejection in most cows. Individual yields ranged from 8 to 96% of the previous parlor yield. To examine the relationship between adrenal cortex sensitivity and the coping process, an ACTH challenge experiment was performed after the changeover period. Cows that released more cortisol after ACTH injection, indicating a higher adrenal cortex sensitivity, had a less enhanced heart rate and a near normal milk ejection during the first AMS milkings (P < 0.05). In conclusion, the reactions toward the changeover to AMS milking varied widely within cows. Adaption to the AMS was easier in animals with a higher adrenal cortex sensitivity to ACTH.