Optimal allocation of limited water supplies for Russet Burbank potatoes

Water shortages in many potato-producing regions have increased the demand for information on irrigating potatoes with limited water supplies. Field studies were conducted at Aberdeen, Idaho in 1988 and 1989 to determine the optimal allocation of limited water supplies for Russet Burbank potatoes. Irrigation amounts equal to 60 or 80% of estimated seasonal evapotranspiration (ET) were applied using various patterns of water allocation. Irrigation deficits were either partitioned evenly over the entire tuber bulking period, or were imposed during two of three designated growth stages (early, mid or late bulking) corresponding to the periods from 0 to 3, 3 to 6, and 6 to 9 weeks after tuber initiation, respectively. A well-watered, 100% ET check was included for comparison. Total yield reductions were greater when irrigation deficits were imposed during the early-mid and midlate bulking sequences than when they were imposed evenly over the entire tuber bulking period or during the early-late bulking sequence. Results relating U.S. No. 1 yields to seasonal water allocation patterns were similar to those for total yield. However, U.S. No. 1 yield reductions were proportionately greater. Irrigation deficits imposed during the early-mid bulking sequence resulted in the lowest specific gravities and the highest percentages of dark ends.     

Zone-subsoiling effects on potato yield and grade

Soil compaction and erosion are problems in many Pacific Northwestern potato fields. We wanted to determine if zone-subsoiling would reduce these problems and improve potato yields and or grade without adversely impacting other production practices. Studies were conducted in Southern Idaho at six locations over two years on different soils and with different irrigation methods to assess the effects of zone-subsoiling immediately after planting on tuber yield and grade. Reservoir-tillage comparisons were made at three locations where sprinkler water application rates were higher than soil infiltration rates. Russet Burbank was represented by eight location-years and Russet Norkotah by two. Zone-subsoiling consistently improved tuber grade or increased tuber size. The biggest improvement was under furrow irrigation. Zone-subsoiling also tended to increase total yield in eight of ten location-years. Reservoir-tillage improved yield and grade, but zone-subsoiling did not without reservoir-tillage when water application rates were high. At no location did zone-subsoiling significantly decrease tuber grade or yield. Zone-subsoiling had no appreciable effects on hill configuration or seed-piece dislocation. Surface cracking and “water piping” occurred under furrow irrigation but were not significant problems. Results were similar for both cultivars. Additional studies will be needed to successfully incorporate zone-subsoiling into commercial production practices     

The role of indigenous wild, semidomestic, and exotic birds in the epizootiology of velogenic viscerotropic Newcastle disease in southern California, 1972-1973.

During an epornitic of velogenic viscerotropic Newcastle disease (VVND) in southern California, free-flying wild birds, captive and free-ranging semidomestic birds, and exotic birds were collected from the quarantine area to determine their role in the epizootiology of the disease. The VVND virus was isolated from 0.04% of 9,446 free-flying wild birds, 0.76% of 4,367 semidomestic birds, and 1.01% of 3,780 exotic birds examined. Three house sparrows and 1 crow directly associated with infected poultry flocks were the only free-flying wild birds from which VVND virus was isolated. Among semidomestic species, ducks, quail, chukars, pheasants, peafowl, pigeons, and doves were found to be infected. Psttacines, pittas, and toucans accounted for 92% of the VVND virus isolations from exotic birds. In addition, domestic Newcastle disease virus (NDV) was isolated from 0.29% of the free-flying wild birds, from 1.65% of the semidomestic birds, and from 0.19% of the exotic birds collected. Hemagglutination-inhibition against domestic NDV was demonstrated in 0.24% of 3,796 wild bird serums, 8.28% of 2,004 semidomestic bird serums, and 3.90% of 231 exotic bird serums tested. Although few free-flying wild birds were infected with VVND virus in this epornitic, the isolation of domestic NDV strains from free-flying wild ducks and mourning doves suggests the potential for transportation of NDV over long distances by migratory birds.     

Effects of naloxone on ad libitum intake and plasma insulin, glucose, and free fatty acids in maintenance-fed sheep

The dose-dependent effects of naloxone on feed intake, and plasma chemicals (insulin, glucose, FFA) purportedly involved in feed intake regulation, were determined in 16-hr fasted sheep that were lean and chronically fed maintenance. Dorset ewes (n = 5) were treated with 0 (saline), 0.3, 1 or 3 mg/kg of naloxone in a generalized randomized block experiment with at least 7 d between successive doses. Feed intakes and plasma insulin, glucose and FFA were determined frequently during 24 hr of ad libitum intake after each naloxone treatment. The 0.3, 1 and 3 mg/kg doses of naloxone reduced (P less than 0.01) the 4-hr feed intake by 30, 40, and 60% respectively, whereas the initial feed intake (10 min) was decreased (P less than 0.05) 45% only by 3 mg/kg naloxone. However, total 24-hr intakes were similar across all doses because intakes between 4 and 24 hr of feeding in sheep treated with 0.3 (839 g), 1.0 (802 g) and 3.0 (1330 g) mg/kg naloxone exceeded (P less than 0.01) that in saline-treated sheep (391 g). Feeding-induced changes in plasma insulin, glucose and FFA concentrations were independent of naloxone treatment, suggesting that endorphinergic control of feed intake may not involve coincidental changes in plasma insulin, glucose and FFA levels which are thought to play a role in systemic regulation of appetite in animals. The endorphinergic regulation of appetite in sheep may involve the central nervous system, rather than peripheral opiate mechanisms that utilize blood-borne signals. Further, the ability of naloxone to suppress appetite in sheep appears inversely related to the duration of fasting or severity of negative energy balance.     

Lamprey gonadotropin-releasing hormone-III selectively releases follicle stimulating hormone in the bovine

Recent studies have shown that lamprey gonadotropin-releasing hormone (l-GnRH) is localized in the mammalian brain, and that l-GnRH-III, can selectively induce FSH secretion in the rat both in vivo and in vitro. Consequently, the purpose of this study was to determine if l-GnRH-III could elicit selective FSH release in cattle and compare this response with that to mammalian luteinizing hormone releasing hormone (m-LHRH). Cattle were chosen as the animal model because previous studies have demonstrated that FSH and LH are secreted by separate gonadotropes in that species. For these studies, crossbred cycling heifers were implanted with jugular cannulae and l-GnRH-III was infused either between Days 9–14 or on Day 20 of the estrous cycle. Blood samples were collected both before and following peptide infusion. Our results demonstrate that during Days 9–14 of the estrous cycle (luteal phase), when progesterone levels averaged between 4 and 5 ng/ml, a dose of 0.25 mg of l-GnRH-III induced the release of FSH (P < 0.05), but not LH. A 0.5 mg dose of l-GnRH-III caused a greater release of FSH (P < 0.01), but still did not induce LH release. Higher doses of the peptide were capable of significantly releasing both gonadotropins. Importantly, during the luteal phase, doses of 0.5 and 2 mg of m-LHRH were ineffective in stimulating FSH, but did elicit marked increases (P < 0.001) in LH. Again, progesterone levels averaged 4–5 pg/ml. In order to assess gonadotropin releasing ability of l-GnRH-III at a different phase of the estrous cycle, some animals were administered the peptide on Day 20, when progesterone levels were below 1.0 pg/ml. At this time, the l-GnRH-III induced the release of LH (P < 0.01), but not FSH. Overall, our results demonstrate that l-GnRH-III can selectively induce FSH in cattle during the luteal phase, whereas m-LHRH was ineffective in that regard. Furthermore, the fact that l-GnRH-III can selectively stimulate FSH when serum progesterone is high, and LH when serum progesterone is low, suggests its actions are under strong control of this steroid. We suggest the FSH releasing capacity of l-GnRH-III in cattle could render this peptide useful for enhancement of reproductive efficiency in this species.     

Treatment of Neonatal Calf Diarrhea with an Oral Electrolyte Solution Supplemented with Psyllium Mucilloid

Dairy calves under 14 days of age with naturally occurring, uncomplicated diarrhea were treated for 3 days with a hypertonic oral electrolyte solution with (n = 15) or without (n = 12) psyllium. Clinical response and clinical pathology data were compared between the 2 groups. Glucose absorption was evaluated on days 1 and 3 by measurement of plasma glucose and lactate and serum insulin concentrations for 4 hours after formula administration. On day 1, glucose, lactate, and insulin concentrations were lower in psyllium-fed calves than in control calves, with significant differences noted in glucose and lactate concentrations at several time points ( P < 0.05). Plasma lactate concentrations were higher at several times in both treatment groups on day 3 than on day 1 ( P < 0.05). Fecal consistency was markedly different in psyllium-fed calves as compared with control calves within 24 hours of psyllium supplementation. Fecal percent dry matter content was lower in psyllium-fed calves than in control calves at least once a day during supplementation and on day 3 compared with day 0 in the psyllium-fed calves ( P < 0.05). There were no significant differences in clinical performance scores, hydration status, arterial blood gas, serum anion gap, electrolyte, or total CO, concentrations. Addition of psyllium to an oral electrolyte solution resulted in immediate alterations in glucose absorption without impairing rehydration in diarrheic calves, but differences were transient and did not affect clinical outcome.