Effects of atmospheric ammonia at 0, 25, and 50 ppm in relation to time on broiler cockerels were studied. Average body weights, feed efficiencies, air sac scores, and paired-lung and bursa of Fabricius weights were determined from 10 birds per replicate at 28, 40, and 49 days of age. Carcass condemnations and USDA carcass grades were measured at 49 days of age.Feed efficiency at 49 days of age was significantly affected (P<.01) by ammonia levels. Broilers subjected to 50 ppm ammonia from 1 through 49 days were least efficient. Broilers subjected to 50 and 25 ppm ammonia from 1 to 28 days and adjusted to 25 ppm ammonia from 29 to 49 days were next least efficient, followed by 50 and 25 ppm ammonia groups from 1 to 28 days and reduced to 0 ppm ammonia from 29 to 49 days. Control birds (0 ppm ammonia) from 1 to 49 days were most efficient.Average body weights, air sac scores, lung weights, and bursa of Fabricius weights as a percentage of live body weight, carcass grades, and condemnations were not significantly affected by treatment.The results indicated ammonia levels of 25 and 50 ppm from day of age in conjunction with Newcastle infectious bronchitis (Mass.) vaccination at 21 days of age can adversely affect feed efficiency of broiler cockerels and thereby increase cost of production. (

White locoweed (Oxytropis sericea Nutt. in T&G) is widespread throughout the short-grass prairies and mountain grasslands and causes chronic poisoning of cattle, sheep, and horses. The objective of this study was to determine the effect of clipping (simulated grazing) on vigor, mortality and toxic alkaloid concentration of white locoweed. One hundred locoweed plants were marked at each of 3 locations (New Mexico, Colorado, and Utah). Plants were stratified into 2 age/size classes: young/small < 5 stalks; older/large > 7 stalks (n = 50 in each class). Pairs of plants within each age class that were as similar as possible were selected, and 1 of each pair (n = 25) was clipped at ground level annually for 4 years. Vigor indices included number of stalks, number of flowering heads, leaf length, and flowering head height. Mortality was recorded and the toxic alkaloid swainsonine was measured. Clipping did not consistently reduce vigor. Flowering heads/plant declined in most clipped plants (P < 0.05), but stalks/plant declined only in large clipped plants in Utah and small clipped plants in New Mexico (P < 0.01), and clipping did not greatly affect leaf length or flowering head height. Clipping did not increase mortality, and did not affect swainsonine concentration. However, there was a natural die-off that may have been related to precipitation. There were negative correlations between precipitation and locoweed mortality (r =-0.42 to-0.84), with most of the marked plants dying during the recent drought. Grazing locoweed for short periods would likely not affect its vigor or toxicity, but its population dynamics were affected by drought.

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Anecdotal evidence suggests that cattle fed alfalfa hay during the winter are inclined to graze locoweed on spring range. Two studies were conducted to compare the influence of feeding alfalfa hay vs grass hay during the winter on subsequent consumption of white locoweed (Oxytropis sericea Nutt. ex T&G) in the spring. Eight cows were daily fed alfalfa hay (15.2% CP in 1998, % CP in 2000) and 8 cows were daily fed grass hay (10.7% CP in 1998, 12i % CP in 2000) plus 20% protein molasses block during the January-April winter feeding period. Treatment groups grazed in separate pastures (8 ha) on white locoweed-infested range in May and June in northern Colorado in 1998 and in northeast New Mexico in 2000. Diets were estimated by bite count. There was no difference in locoweed consumption between the 2 groups (P > 0.22). Cattle grazed locoweed for 5% of diets in Colorado and 10% of diets in New Mexico. Feeding alfalfa hay over winter did not predispose cattle to graze locoweed in the spring. Previous research showed other feeding practices or supplements do not affect locoweed consumption or poisoning. Prevention of locoweed poisoning requires denying access to locoweed when it is relatively more palatable than associated forages.