The objective of this prospective field study was to evaluate the effects of extending the lactation period of high-yielding dairy cows on milk production, udder health characteristics, and development of body condition. On 40 d in milk (DIM), an examination of the genital tract (transrectal palpation, sonography, vaginoscopy) was performed. Cows without signs of clinical endometritis were blocked by parity and were randomly allocated to 1 of 3 experimental groups with a voluntary waiting period of 40, 120, and 180 d, respectively (G40, n = 135; G120, n = 141; G180, n = 139). Mean daily milk and energy-corrected milk production did not differ between the 3 groups regarding the first 305 d or for the whole lactation (d 1 and up to dry off, culling, or 600 DIM). In late lactation (306 to 600 DIM), G40 had lower average productivity (23.8 kg) compared with G120 (26.5 kg), with G180 showing intermediate values (25.7 kg). The extended lactation groups showed greater persistency, as the rate of decline based on a Wilmink function was lower for G120 (c = −0.063 and −0.045 for milk and energy-corrected milk, respectively) and G180 (c = −0.061 and −0.047) compared with G40 (c = −0.071 and −0.056). We found no difference between the 3 groups regarding the evaluated udder health characteristics (somatic cell count, incidence of mastitis, and days off milk due to mastitis). More cows in G180 (7.9%) were culled due to low productivity compared with G40 (0.7%) and as a tendency compared with G120 (2.8%). Moreover, cows of G180 showed higher median body condition score at the time of dry off compared with cows of both G40 and G120 (3.50 for G180 vs. 3.25 for both G40 and G120). At the time of dry off, G180 cows also had greater backfat thickness (25.0 mm) compared with both G40 (22.2 mm) and G120 cows (21.6 mm). Based on our results, the extension of the voluntary waiting period of highyielding cows up to 120 d has no adverse effects regarding milk production, involuntary culling, udder health, or BCS gain.

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The objective of this prospective field study was to evaluate the effects of extending the lactation period on various reproductive measurements of highyielding Holstein cows. On 40 d in milk (DIM), cows were gynecologically examined (transrectal palpation, sonography, vaginoscopy). Cows without signs of clinical endometritis were blocked by parity and were randomly allocated to 1 of 3 experimental groups with a voluntary waiting period (VWP) of 40, 120, and 180 d, respectively (G40, n = 135; G120, n = 141; G180, n = 139). Cows of G120 and G180 were reexamined at the end of the VWP. If natural estrus was detected within 46 d after the end of the VWP, an artificial insemination was performed. If no estrus was detected, the respective cows were synchronized by applying the classical Ovsynch protocol. We found no difference in the proportion of cows in which estrus was detected between 40 to 86 DIM or in the days to first estrus between the 3 groups. Estrus detection in this period was lower in cows with body condition score <3 on 90 DIM compared with body condition score ≥3 (61.5 vs. 76.0%) and in cows with high energy-corrected milk production (ECM) on 92 DIM [58.6 vs. 70.1%, for cows with higher and lower than the median (39.9 kg) ECM, respectively]. The proportion of cows that estrus was detected within 46 d after the VWP was greater in G120 (88.9%) and G180 (90.8%) compared with G40 (70.4%). These effects were more apparent in cows with high ECM. The rate of estrus detection and of becoming pregnant in this period was greater for G120 (hazard ratio = 2.2 and 1.6, respectively) and for G180 (hazard ratio = 2.4 and 1.8) compared with G40. Cows in both groups with extended lactation had greater overall first service conception rates (G120 = 48.9%; G180 = 49.6%) and a lower number of services per pregnant cow (G120 = 1.56 ± 0.1; G180 = 1.51 ± 0.1) compared with G40 (36.6%; 1.77 ± 0.1). We observed no difference in pregnancy loss or in the proportion of cows culled up to 305 d of lactation between the 3 groups. The number of Ovsynch protocols per 1,000,000 kg of ECM was reduced by 75% in G180 and by 74% in G120 compared with G40 (5.9 vs. 7.1 vs. 25.1). In conclusion, extending the lactation of dairy cows can improve main reproductive measurements in high-yielding cows.

a b s t r a c tDiarrheic calves are fed with milk or milk replacer and oral rehydration solutions (ORS) to ensure energy and electrolyte supply. An easy and time-saving method is the preparation of ORS in milk. As milk-based ORS are hypertonic solutions administration of them may trigger thirst. Therefore, we hypothesized that restrictively fed calves receiving ORS prepared in milk had a higher water intake than restrictively and ad libitum fed calves receiving ORS prepared in water during diarrheic episodes.The daily water intake was measured in 100 individually-housed Holstein Friesian calves from day 2 to 21 of life. One group of the calves was fed with restrictive amounts of milk, the other group got milk ad libitum by an automated milk feeder. Nearly all calves spontaneously developed diarrhea within the observation period from day 2 to 21 of life. In cases of diarrhea the restrictively-fed calves received ORS prepared in milk or ORS prepared in water two hours after their milk meal, whereas the ad libitum-fed calves only got ORS prepared in water. All calves had ad libitum access to water. The daily intake of water, milk, and ORS and weight gain during diarrheic episode were determined. Data were expressed as arithmetic means ( 7standard deviation) and analyzed by using a oneway ANOVA or repeated-measures ANOVA.From day 2 to 21 of life calves fed with restrictive amounts of milk had higher water intakes related to the total dry matter intake (DMI) with 1.6 L/kg of total DMI than ad libitum-fed calves (0.9 L/kg of total DMI) per day. In cases of diarrhea water intake increased in all feeding groups. The calves receiving milk-based ORS had the highest water intake with 1.7 L/d during the period of diarrhea compared to the calves received ORS prepared in water. Moreover, the calves fed ORS in milk showed with 4.6 L/d the highest daily ORS intake. There were no differences in the duration of diarrhea or the daily weight gain during period of diarrhea between the feeding regimens. Therefore, it can be concluded that all feeding regimens were suitable in the treatment of calf diarrhea. The simplest method to treat calves suffering from diarrhea is the preparation of ORS in milk, but then ad libitum availability of water is absolutely necessary. Moreover, calves drink considerable amounts of water within the first 3 weeks of life and therefore should be provided with water for animal welfare reasons.

In case of diarrhea calves are treated with oral rehydration solutions (ORS), which are known to increase abomasal pH and inhibit milk clotting in vitro. Nevertheless, recent studies have shown that ORS with HCO3(-) ≤ 62 mmol/L do not interfere with abomasal milk clotting in healthy calves. However, in diarrheic calves, feeding ORS and milk simultaneously may disturb abomasal curd formation and exacerbate diarrhea due to faster abomasal passage of ingesta. Therefore, the aim of the present study was to ultrasonographically examine abomasal milk clotting and diameter after feeding milk and milk replacer (MR) with and without ORS to healthy and diarrheic calves. Abomasal curd formation and diameter in healthy and diarrheic calves were ultrasonographically imaged before and after feeding milk, MR and ORS prepared in milk or MR. Feeding mixtures of milk or MR with ORS did not cause any remarkable differences in the ultrasonographic images of abomasal content. Moreover, abomasal milk clotting was not disturbed due to diarrhea. Statistically significant differences of abomasal diameter after feeding between healthy and diarrheic calves indicated that abomasal emptying is delayed in diarrheic calves. Hence, further studies are needed to determine reasons for decelerated abomasal passage in calves suffering from diarrhea.

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Zusammenfassung Gegenstand und Ziel Die thermische Enthornung von Kälbern stellt einen mit Schmerz und Stress verbundenen Eingriff dar. Verschiedene Verfahren der Schmerzausschaltung sowie die unmittelbaren Auswirkungen auf physiologische, biochemische und ethologische Prozesse wurden bereits ermittelt. Ziel der Studie war zu evaluieren, ob die Enthornung selbst, das Schmerzmanagement oder das Alter der Kälber zum Zeitpunkt des Eingriffs die Gesundheit der Tiere beeinflusst. Material und Methode Die Studie wurde als randomisierte, dreifach verblindete, prospektive Untersuchung an 337 weiblichen Deutsch-Holstein-Kälbern durchgeführt. Die Enthornung der Tiere erfolgte zwischen dem 4. und 10. Lebenstag oder zwischen dem 15. und 28. Lebenstag. Jedes Kalb wurde dabei einer von 9 Behandlungsgruppen zugelost, die sich in Art und Umfang der analgetischen Komponenten (Sedation, Leitungsanästhesie, Antiphlogese vs. Plazebo) unterschieden. Alle Kälber, bis auf die aus der Gruppe der scheinenthornten, wurden thermisch enthornt und sämtliche Tiere unterlagen einer klinischen Überwachung beginnend vor bis 4 Wochen nach dem Eingriff. Die erhobenen Befunde wurden als Boniturnoten unter Verwendung des Schwellenwertkonzepts mit dem Statistikprogramm SAS ausgewertet. Ergebnisse Die Enthornung beeinflusste die Gesundheit des Respirationsapparats der Kälber. Tiere, bei denen die Enthornung lediglich simuliert wurde, zeigten die niedrigsten Erkrankungsraten. Am häufigsten erkrankten Kälber, bei denen die Enthornung ohne Analgesie erfolgte. Die Varianten des Schmerzmanagements senkten das Risiko respiratorischer Erkrankungen in unterschiedlichem Maß. Die zu einem früheren Zeitpunkt enthornten Kälber wiesen seltener eine abweichende innere Körpertemperatur auf als ältere Kälber. Schlussfolgerung Die Enthornung stellt ein Risiko für die Gesundheit des Respirationsapparats von Kälbern dar. Sind Hornloszüchtung oder die Haltung horntragender Tiere nicht möglich, kann durch ein adäquates Schmerzmanagement das Risiko respiratorischer Erkrankungen gesenkt werden. Die Enthornung zu einem frühen Zeitpunkt ist möglich und sinnvoll. Klinische Relevanz Die Studie belegt die Bedeutung eines adäquaten Schmerzmanagements zur Enthornung für die Kälbergesundheit.

The administration of oral rehydration solutions (ORS) is an effective method to treat dehydration and acidosis in calves suffering from diarrhea. The ORS can be prepared in water or milk. The aim of the present study was to elucidate how fluid and acid-base balance change after feeding milk compared with ORS prepared in water or milk to diarrheic calves. Calves (n = 30) with naturally acquired diarrhea were sequentially assigned in a 2:1 ratio to the following pretreatments: milk and water-ORS (pretreatment 1; n = 20 calves) or milk-ORS (pretreatment 2; n = 10 calves), respectively. The assignment was done on the day of diarrhea diagnosis. On d 3 ± 1 following assignment to pretreatment group, and after a fasting period of 9 h, diarrheic calves were subjected to the following treatments: 2 L of milk (pretreatment 1; n = 10 calves), water-ORS (pretreatment 1; n = 10 calves), or milk-ORS (pretreatment 2; n = 10 calves). Blood samples were taken before and at several time points until 6 h after feeding. Plasma protein, osmolality, and electrolytes were determined and a blood gas analysis was performed. Change in plasma volume was calculated according to plasma protein, and water intake during the experimental period was recorded. Plasma volume was increased 30 min after feeding water-ORS or milk but the increase was less pronounced after feeding milk compared with water-ORS. After feeding milk-ORS, no significant increase in plasma volume could be detected. Because of the pretreatment, plasma osmolality was higher in calves fed milk-ORS, but no change in plasma osmolality after feeding was detected. No difference in water consumption between the treatment groups was noted within the observed 6-h period. The pH was increased after feeding milk-ORS, whereas water-ORS and milk-feeding did not increase pH in blood. Pretreatment with milk-ORS resulted in higher baseline d -lactate concentration, but feeding milk-ORS reduced d -lactate values after feeding. In calves with diarrhea, plasma volume increased more quickly and to a greater extent after feeding water-ORS; thus, we recommend treating diarrheic calves with water-ORS before supplying milk. Nevertheless, diarrheic calves need milk to fulfill their energy needs. The administration of ORS in milk combined with free water access is more advisable than feeding milk exclusively because milk has no alkalinizing ability and contains less sodium. However, the effects of milk-ORS feeding on d -lactate levels in diarrheic calves need further elucidation.