EFFECTS OF OVIPOSITION TIME, HENAGE,AND EXTRA DIETARY CALCIUM ON EGGCHARACTERISTICS AND HATCHABILITY R !I NOVO, L 'E GAMA, and M CHAVEXRO SOARES' Instituto Superior de Agronomia, 1399 Lisboa Codex, Portugal Phone: (01) 3638161 F M : (01) 3635031 measured by SG and eggshell weight [8, 91 DESCRIPTION OF PROBLEM Reis et al [6] also observed that coarse limeEggshell quality as measured by egg specific gravity (SG) has frequently been associated with hatchability of eggs from broiler breeder hens [l, 2,3,4,5,6] Research indicates that a SG of 1.080 is the dividing point between good and poor hatchability [7] Researchers have reported that broiler breeder hens fed in the afternoon exhibit a sig&cant improvement in eggshell quality as To whom correspondence should be addressed stone supplied in the afternoon slightly increased the SG of broiler breeder eggs, but markedly improved embryo viability The literature also indicates that SG of broiler breeder eggs increases as time of laying becomes later in the day [l,21, althoughhatchability of eggs laid in the afternoon is not significantly greater than that of eggs laid during the morning [l] However, further Downloaded from http://japr.oxfordjournals.org/ by guest on June 30, 2014 Primarv Audience: Breeder Production Managers Researchers EXTRA DIETARY CALCIUM 336 same feed in separate sex feedings [15], as diets used by the breeder hen appear to have no detrimental effects on male performance [14] All ration feeding occurred at 08:30 hr Hens received approximately 163 and 157 g of feed per bird at 46 and 65 wk of age respectively, to maintain body weights recommended by the primary breeder [16] The hens had consumed their feed allowance by approximately 11:OO hr each day All birds consumed water ad libitum In the pen assigned to CS treatment, coarse limestone (4 g/bird daily) was scattered on the litter at 16:30 hr The litter was made of naturally dark wood shavings (eucalyptusbark), so that white limestone particles were very visible; the birds rapidly consumed them The Limestone supplement had particles ranging from to mm in diameter, with an average solubility of 37.3+3.3% (five repetitions) determined as described by Keshavarz et al [lq.Extra dietary calcium supplement was provided for consecutive days at both 46 and 65 wk of flock age Calcium distribution began days before the date of first egg collection for experimental purposes (Table 1) EGG COLLECTION AND HANDLING At 46 and 65 wk of age eggs were collected for and days, respectively (Table l),at hr intervals beginning at 08:OO hr and ending at 18:OO hr Eggs laid before 08:OO hr were removed from the nests and were not used in this experiment Eggs that were cracked, very dirty, misshapen, or of extreme size were culled From each pen and collection time, a random sample of 150 hatching eggs was obtained and eggs were then individually marked Eggs from each day’s production reached the hatchery at 12:45, 16:45, and 18:45 hr The eggs were then individually weighed to the nearest 0.1 g, and SG was determined in graded sodium chloride solutions kept at room temperature (about 20°C) and ranging from 1.060to 1.090,with an increment of 0.005 units between successive solutions The concentration in which the egg barely floated beneath the surface indicated egg SG Eggs that did not float in any of the solutions were assigned a SG of 1.095, and those that floated in all solutions were assigned a SG of 1.060.After SG measurement, the eggs were rinsed in warm tap water and dried in a stream of warm air at approximately 20°C MATERIALS AND METHODS SOURCE OF EGGS The study was carried out over two periods, from November to December 1994 and from March to April of the following year, using eggs from one commercial flock of approximately 13,900 broiler breeder hens (Cobb 500) at 46 and 65 wk of age Equal numbers of birds were arbitrarily assigned to each of two identical pens of one building at 0.25 m2 per female, in order to determine the effects of two treatments: no extra calcium supplementation (NC) and extra calcium supplementation (CS) Natural daylight was supplemented with artificial light to give a 16 hr photoperiod (on 0790 hr, off 23:00 hr) Daily low and high in-house air temperatures ranged from 17 to 24°C and 16 to 24°C at ages 46 and 65 wk, respectively All birds received a commercial broiler breeder diet (16.50% CP, 2800 kcal ME,/kg, 3.10% calcium, 0.35% available phosphorus) formulated to meet or exceed National Research Council [14] requirements, as previously described [6] Both sexes received the Downloaded from http://japr.oxfordjournals.org/ by guest on June 30, 2014 studies showed that hatchability [lo] and embryo viability [ll]were si&icantly lower in fust-of-sequence eggs than in subsequent eggs within a laying sequence The fust egg of a sequence is usually laid relatively early in the day and the remainder laid later on each following day; therefore, a high proportion of eggs laid in the early morning of any given day should be first-of-sequence eggs [12] In addition, sequence length in feed-restricted broiler breeder hens reaches a prime mean length at 32 wk of age, then quickly shortens with advancing hen age [13]; therefore, the incidence of first-of-sequence eggs increases with hen age We conducted the present study to determine the effects of oviposition time, hen’s age, and extra dietary calcium on egg weight (EW), SG, EW loss during the first 18 days of incubation, fertility, embryo viability, age of embryonic death in fertile eggs, and hatchability of eggs from feed-restricted broiler breeder hens under commercial conditions Specifically, we wished to ascertain whether the effect of calcium supplementation varied with hen age by affecting SG and with time of oviposition through interaction with time of calcium absorption Field Report 337 NOVO et al TABLE Egg collection and calcium supplementation for broiler breeders at two different periods (46 and X X April - X November 24 X X April X X November 25 X - April X - Eggs from each treatment and collection time were then placed in setter trays (150 eggshay) INCUBATION AND HATCHING Incubation was initiated at 2200 hr on the day of egg collection in electronically controlled single-stage incubators (Petersime 576) The ten experimental trays corresponding to five different collection times and two treatments were randomly placed in one quadrant (front right) on the same trolley, which was then filled with other eggs Quadrant and trolley positions were the same on all collection days to reduce possible position effects AU eggs were fumigated in the incubator at incubation temperature on the day of setting, using 20 g of potassium permanganate and 30 mL formalin (400 g/L) per m3 incubator space with the ventilators closed for 20 Eggs were automatically turned 90" every hour and incubated at conventional temperature and humidity conditions, as previously described by Roque and Soares [5] The eggs were individually candled on the 18th day of incubation, using a hand candling lamp Infertile eggs and eggs containing early dead embryos were removed and broken out for macroscopic examination The eggs with apparently living embryos were individually weighed to the nearest 0.1 g Weight loss was calculated by difference and expressed in absolute terms (g) and as a percentage of initial fresh egg weight The eggs were quickly transferred to hatcher baskets, randomly distributed in the front part of the same trolley, and placed in a hatcher (Petersime 192) operated at conventional conditions, as outlined by Roque and Soares [5].Chicks and unhatched eggs were taken off at 21 days and 12 hr postincubation Saleable hatched chicks and culls (unmarketable chicks) were recorded All eggs removed at candling, and unhatched eggs at the time of taking off the hatch, were broken out, examined macroscopically, and assigned to one of the following categories: infertiles, early-dead germs (embryo deaths during 1to days of incubation),mid-dead germs (deaths during to 18 days), late-dead germs (deaths after 18 days), pipped (beak penetrated eggshell but chick did not emerge), and rots (contaminated) From the data, percent hatchability (number of saleable chicks hatched per all eggs set x 100) and percent embryo viability (number of saleable chicks hatched per number of fertile eggs set x 100) were calculated A total of 7500 eggs were used in the fust period (150 eggs per collection time x daily collection times x days x treatments), and 6000 eggs were used in the second period (4 days) Data were statistically analyzed by analysis of variance [18,19,20] RESULTS AND DISCUSSION The interaction between oviposition time and calcium supplementation was significant only for embryo mortality up to days and contaminated eggs (Table 2); thus, it seems that the effect of ovipositiontime was basically the same for both treatments On the other Downloaded from http://japr.oxfordjournals.org/ by guest on June 30, 2014 November 23 JAPR EXTRA DIETARY CALCIUM 338 TABLE Significance of different sources of variation in the preliminary analysis VARIABLE SOURCES OF VARIATION Treatment Breeder Age (A) Oviposition Time (0) NS *** ** ** ** I** $8 f Egg specific gravity Egg weight at set, g Fertility, % Hatchability, % I NS I t OXT OXA NS * *.* NS NS NS *** NS NS * *** NS **: * :** NS *** *t *P