Page 14—Poultry Notes Supplement to Lancaster Farming, Saturday, Sept. 25,1993 \ Lancaster Fanning I V I U Benchmarks in Layer Performance Paul H. Patterson It is easy to document prog ress in the layer industry with the excellent records that are kept on commercial white egg strains today. In his “Egg Eco nomics Update” Don Bell, poultry specialist at Riverside, Calif, looked back on 18 years of summarizing performance records of table egg flocks and the progress that has been made (Table 1). During the period from 1973 to 1991, eggs pet hen housed has improved 45.4 eggs, or 2.5 eggs per hen per year. The average rate of egg production has increased by 13.4 percent Table 1. Mortality % HH eggs HD % Weekly Total Year 172.0 663 .33 10.6 183.3 6.94 .26 9.9 184.6 70.9 .27 10.1 186.4 70.8 .29 11.0 185.5 70.8 .30 11.3 190.0 71.8 .28 10.5 1973 1974 1975 1976 1977 1978 205.4 76.0 >, .20 8.0 205.4 76.4 .22 8.8 204.2 75.4 .22 8.8 207.1 76.1 .22 8.6 210.5 76.5 .20 7.9 212.5 76.6 .20 8.1 214.6 78.6 .71 6.8 217.4 79.7 .15 6.0 Table 2 1991 HH eggs Hen-Day HD peak Mortality Feed Feed Undcr flocks to 60 wk ave % 28-31 wk % lb/100 hd Ib/doz grade % Best 25% 229.1 83.4 92.7 2.6 19.2 2.92 _ 2.2 Poorest 25% 204.3 75.3 85.2 10.6 23.0 3.45 5.7 Grilless Pan Feeders n or .74 percent per year. Mortal ity percentages have gone down weekly from .33 to .15 percent, while total figures have dropped from 10.6 to 6.0 percent (.26 percent per year). Birds today tend to weigh less than they did 20 years ago, and with this trend feed consump tion has been reduced from .234 pound per hen per day to only .212 pound. This repre sents an annual improvement of .12 pound per 100 hens per day during the 18-year period. Feed conversion (pounds of feed per dozen eggs) has improved from 3.86 to 3.19 pound in 18 years, with an annual drop of .04 pound per dozen per year. Feed Feed Under lb/100 hd. Ib/doz. grade % (from 25 to 60 wks) 23.4 3.86 24.3 3.81 23.6 3.71 23.4 3.60 22.9 3.56 23.6 3.62 (from 21 to 60 wks) 22.4 3.54 22.1 3.48 5.50 22.0 3.50 5.51 21.9 3.45 5.61 21.7 3.41 5.33 21.7 3.38 4.86 21.3 3.26 4.97 21.2 3.19 4.02 World Cla SSSfTn Heaters wfm mw _ V _“Zir -wyi;-" HILo Pan While these numbers are not the most that can be expected from today’s laying hens, they represent an “average” and demonstrate the progress that has been made over 18 years of keeping records. Ranges in performance are shown for 1991 in Table 2. These arc the corresponding “best 25 per cent” and “poorest 25 percent” records of 360 flocks summarized. Compared to the 1991 aver age flock, there is the oppor tunity to get an additional 11.7 eggs to 60 weeks. Don’t be satisfied with an average 79.7 percent hen day egg production when the best 25 percent are getting 83.4 percent and peaks of 92.7 percent. Furthermore, better flocks have less mortali ty, fewer undergrades, and do it all with less feed. As a target, you can compare your flocks with this range of performance, and ask the hard questions: why is my flock not performing as well in certain categories listed below? With out good records, and the time to really look them over and evaluage flocks performance, it’s difficult to get to the bot tom of a bird health, equip ment, or performance problem. Dietary Treatment For Laying Hens With Kidney Damage Paul H. PAtterson Assistant Professor, Poultry Science, Penn State Researchers at Penn State t Adult Turkey Feeder Platform Scale Wednesday, September 29 Thursday, September 30, Lancaster Host Resort University have shown that when Leghorn pullets are fed laying hen diets during the growout period (6 to 18 weeks), formation of kidney stones or uroliths are induced in the ureters and urine collect ing ducts of the kidney. Compared with the young pullets requirements, layer rations contain high levels of calcium (3.5 to 4.0 percent) and relatively low levels of available phosphorus (.4 to .5 percent). Pullets fed these rations will exhibit, in addition to stones, kidney atrophy, fiber formation, tissue mineraliza tion, asymmetry and a reduc tion in die number of urine fil tering units. These symptoms are similar to the degenerative renal dis ease “urolithiasis”. In addition, infectious bronchitis virus (IBV) has been suspected as a cause of urolithiasis, based on the evidence that some strains of IBV cause kidney damage similar to field outbreaks of urolithiasis. In experimental work com bining the effects of the “Gray” strain of IBV and layer rations, urolithiasis incidence has been observed at between 8.6 and 25 percent, and kidney damage between 25.8 and 58 percent. Unfortunately, the degree of kidney damage may not be realized until later in the adult life of the hen when accumu lated kidney calcium deposits and loss of functional tissue results in a drop in egg produc tion and increase in hen mortal Poultry Leader Feed Bins ity! What is a egg-producer to do if these circumstances hap pen to your birds? Prevention is the best cure, by closely monitoring the cal cium levels fed to your pullets and ensuring adequate IBV protection with a polyvalent vaccination program. If you still are faced with kidney damaged hens, there are some remedial treatments that can be applied in preventing further growth of the kidney stsones. These calcium deposits are caused in laige part because of a metabolic alkalosis brought on by an increase in the cation;anion ratio of the ration. This leads to an increase in urine calcium concentration, a decrease in the H+ ion concent ration, and providing an excel lent medium for precipitation of calcium-urate, the primary mineral in avion uroliths. Treatment lies with the strategy of increasing dietary H+ ion concentration (more acid) in hopes of reducing urine pH and dissolving urin ary calcium. Calcium solubil ized by urine acidification can then be excreted without preci pitation in the kidney. These are several means of modifying dietary pH or H+ ion concent ration to prevent kidney stone enlargement and dissolve pre formed deposits. Ammonium chloride added to the diet at the O.S percent level has been suc cessful in reducing calcium induced kidney damage and stone formation, however, it (Turn to P»go 15) jd/fiSTRB4/# r Mventilation systems * w A Division of (gSf) K Jiss*« s * K » ' «1 1 . ,*3*. ♦ Aj Ventilator Controls Chain Feeder Fans - ' l' "' "' Nesting System
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