Settable Eggs Research Articles

Daily Energy Allotments and Performance of Broiler Breeders.: 2. Females

Arbor Acres broiler breeder hens, 21 to 61 wk of age, were given the daily ME level recommended by the primary breeder for their age and level of production (100% AA) or were given 94 or 88% of that amount. The reduction in daily energy allotment had no effect on age at 50% or age at peak production, but there was a highly significant linear decrease in the eggs per hen from 165 ± 2.8 in hens given 100% AA to 149 ± 3.2 and 141 ± 3.8 in hens given 94 and 88% AA. The percentage of nonlaying hens between 44 and 60 wk of age was substantially increased as daily energy allotment was reduced. The percentage settable eggs was significantly lower in the 100% AA group, but no differences in fertility or hatchability were seen. Chicks per hen fell from 123 ± 2.4 to 116 ± 2.4 to 102 ± 2.6 as energy allotment was progressively reduced. Dietary energy allotment had no effect on egg weight, shell weight, shell characteristics, or proportion of albumen and yolk. Chick weight was unaffected but chicks’ liver weight increased with increasing dam energy intake. Percentage lipid in hens’ carcasses increased with increasing energy intake and percentage protein and percentage ash decreased.

The Use of Feed Restriction for Improving Reproductive Traits in Male-Line Large White Turkey Hens.: 2. Ovary Morphology and Laying Traits

The influence of feed restriction during rearing was investigated in male-line Large White breeder hens with regard to effects on ovarian morphology, egg production, laying patterns, and egg characteristics. Two hundred poults were reared from 4 to 28 wk of age under four treatments as follows: full-fed controls (FF), low-protein diet (12% CP from 12 to 28 wk; LP), and reduced BW (10 to 20% lower BW than FF; R10 and R20). At photostimulation (28 wk), all birds consumed a commercial breeder diet ad libitum for the remainder of the study (48 wk of age).Settable egg production (eggs per hen) to 48 wk for all hens, and those in lay was: FF, 39.4 (48.6); LP 42.7 (51.7); R10, 41.4 (52.8); R20, 40.7 (55.4). Inferior egg production per bird in R10 and R20 hens reflected a reduced persistency of lay. At first egg, hens of all treatments had a mean of 4.9 postovulatory follicles (POF) not accounted for by an egg. Number of unreconciled POF correlated with abdominal fat pad weight (P ≤ .01). Ovary weight correlated with BW (P < .0001) and fat pad weight (P < .0004). Proportion of yolk and shell in the egg and egg specific gravity were improved with feed restriction. Sequence length was longest in R20 treatment hens and pause length shortest in R10 and R20 hens. Incidence of multiple-follicle sets was reduced in the R10 and R20 treatments. Feed restriction during rearing can potentially improve laying characteristics by altering ovarian morphology without limiting shell quality or yolk size. Quantitative feed restriction was most effective at improving egg quality, reducing average pause length, and reducing ovarian multiple-follicle sets. If problems with persistency of lay are addressed, the R10 and R20 treatments are the recommended rearing restriction treatments for male-line turkey breeder hen candidates.

The Use of Feed Restriction for Improving Reproductive Traits in Male-Line Large White Turkey Hens.: 1. Growth and Carcass Characteristics

The influence of feed allowance during rearing was investigated in male-line Large White breeder hens. A flock of 200 poults was reared from 4 to 28 wk of age under four treatments as follows: full-fed controls (FF), lowprotein diet (12% CP from 12 to 28 wk; LP), and reduced BW (10 or 20% lower BW than FF; R10 and R20). At photostimulation (28 wk), all birds consumed a commercial breeder diet ad libitum for the remainder of the study (48 wk of age).Body weight differed among treatments during most of rearing. The LP birds were similar in BW to the R10 birds at 28 wk of age. By 40 wk of age, growth curves of all treatments became similar, with the R20 group having lower BW. Feed restriction reduced frame size during rearing. Flock uniformity in the R10 and R20 treatment hens was reduced during rearing, but improved early in the breeder period. Feed restriction reduced breast muscle and abdominal fat pad weight early in lay, except for the LP group. Liver lipid content increased throughout the breeder period. Changes in liver weight followed the pattern of BW changes. Total carcass protein content changes in time reflected breast muscle mass changes. In R20 hens, carcass lipid content was reduced and protein content increased. Sexual maturity was delayed in the R20 hens. Body weight at first egg was negatively correlated with settable egg production (r = –.37, P ≤ .0015). The R20 treatment is recommended for male-line turkey breeder hen candidates during rearing.

Breeding Habitat Segregation of Wood Frogs and American Toads: The Role of Interspecific Tadpole Predation and Adult Choice

In western North Carolina, adult wood frogs and American toads often occur syntopically but segregate with respect to breeding habitat. American toads arrive at breeding ponds 4-10 wk after wood frogs and typically select breeding sites that lack wood frog tadpoles. In an experiment conducted in seminatural ponds, adult toads completely avoided ovipositing in ponds with wood frog tadpoles. Additional experiments strongly suggest that predation of wood frog tadpoles on toad eggs and larvae is the primary reason for the evolution of adult avoidance behavior in toads. In one set of experiments, toad eggs and hatchlings suffered complete mortality within two days after being placed in artificial ponds containing natural densities of wood frog tadpoles. Similar mortality occurred when eggs and hatchlings were introduced into natural breeding sites. In one experiment in which 2000 toad hatchlings were added to natural ponds, all were killed and consumed within 45 min by wood frog tadpoles. Although tadpoles of most anurans are considered to be microphagous suspension feeders that occupy lower trophic levels of food chains, a growing body of evidence indicates that many tadpoles can temporarily shift feeding modes to become upper level, macrophagous predators. Because facultative predators such as wood frog tadpoles often reach far higher densities in ponds than do top predators, their role in structuring aquatic communities via opportunistic predation may be more important than previously realized.

Effects of Increased Rearing Period Body Weights and Early Photostimulation on Broiler Breeder Egg Production ,

Broiler breeder pullets were subjected to photostimulation (PS) at either 14, 17, or 20 wk of age after attaining greater than recommended BW during rearing in order to determine effects on age at onset of lay, egg weight, and egg production. During rearing, feed was consumed ad libitum (AL) or provided in allotments resulting in growth to projected BW of 2.8 (heavy, HV) or 2.3 kg (light, LT) at 20 wk. Rearing period feeding and age at PS treatments made up a 3 × 3 factorial arrangement. A single restricted feeding program was provided during lay.Although age at first egg in the AL treatment was earlier than in HV and LT treatments, total production by HV and LT birds was greater because peak and postpeak production by AL birds were depressed. Relative to PS at 20 wk, PS at 14 and 17 wk advanced age at first egg and increased cumulative production to 30 wk. However, early PS decreased peak production and, therefore, did not affect total production. Mean egg weight and settable egg production (egg weight > 50 g) were increased in HV and LT treatments. Egg weight and settable egg production were not affected by age at PS. These results indicate that the onset of lay by broiler breeders can be advanced by early PS and that increased BW facilitates this. However, allowing greater BW during rearing does not compensate for reduced early egg weights and results in decreased total production and mean egg weights when feed is provided at recommended levels during lay.

Feed resource base for scavenging village chickens in Sri Lanka.

The productivity of a population of scavenging village chickens in Sri Lanka has been assessed, and the scavenging feed resource base has been measured and analysed. The laying period lasted 34 +/- 13 days and the batch size was about 20 eggs. The households ate 71% of the egg production. The mean egg weight was 48 g and the mean size of a set of eggs was 9.4. The hatching percentage was 67 +/- 32 and the liveweight at 70 days averaged 313 g with a range of 142 to 492, by which time 65% of the chicks hatched had died. The age at first lay averaged 211 days when the pullets weighed 1,160 g. The broody period lasted from 3 weeks to 4 months depending on whether the hen hatched eggs, and for how long she tended the brood. The laying hens were actively scavenging for most of the daylight hours. The average amount of scavenged feed per household flock per day was 550 g dry weight with a proximate composition of 9.4% crude protein, 9.2% ether extract and 5.4% crude fibre. More than 70% of the feed intake was household refuse (27% cooked rice, 30% coconut residue, 8% broken rice and 36% other scraps). The remainder was from the environment (13% grass shoots, 8% small metazoans and 7% paddy rice). Proximate analyses of crop contents, household refuse and its major components were carried out. Dietary Ca and P levels were low in the village, as were plasma levels of these minerals. On a balanced commercial diet plasma Ca was still lower than that of hybrid commercial chickens. Suggestions are made for improving the productivity of the scavenging system with no requirement for inputs, and with inputs.

Lipid and fatty acid compositional differences between eggs of wild and captive‐breeding alligators (Alligator mississippiensis): an association with reduced hatchability?

Fertile eggs were obtained from the nests of wild and captive‐breeding alligators in Louisiana, USA. Whereas embryo hatchability ofthe wild eggs was 94%, in the captive eggs it was only 500%. Analysis of the lipid and fatty acid compositions of the yolks showed extensive differences between the two sets of eggs. In particular, the lipids of the yolks from the captive eggs displayed considerably lower levels of C20 and C22 polyunsaturated fatty acids and higher levels of C18 polyunsaturates than the wild eggs. More specifically, overall levels of n‐6 polyunsaturates were increased at the expense of n‐3 acids in the captive eggs. In view of the specific role of C20 and C22 polyunsaturated fatty acids in embryo development, it is proposed that the yolk fatty acid compositional differences and the difference in hatchability are associated.

The Effect of Candling on the Hatchability of Eggs from Broiler Breeder Hens

In many commercial hatcheries candling is maintained as a routine operation, assuming that the removal of “clear” eggs at transfer can improve hatchability and chick quality. However, in the published literature, few data exist to support the benefits of this routine. A series of experiments was conducted to evaluate the influence of candling on hatchability and chick quality. Eggs from breeder flocks at seven different ages were used.Candling did not alter average hatchability when calculations were based on total number of eggs set (84.53 vs 84.07%, respectively, for candled and control eggs), as well as on the number of eggs with live embryos at 18 days of incubation (95.65 vs 95.89%, respectively, for candled and control eggs). There were no significant differences observed due to flock age.Average chick quality was slightly improved by candling when culls were expressed as a percentage of total settable eggs (0.84 vs 0.97% of culls). For flocks 63 weeks of age, a positive effect was also observed (0.93 vs 1.49% of culls).

Influence of saline drinking water on eggshell quality and formation

Many studies have shown that saline drinking water supplied to mature laying hens at concentrations similar to those found in underground bore water has an adverse effect on eggshell quality and on the incidence of eggshell defects. This response can be observed in the absence of any adverse effects on production parameters such as food intake, egg production and egg weight. Strain differences appear to exist, and even within a strain there is considerable variation in the responses of individual hens to saline drinking water. The sensitivity of the hen also increases with age with a greater occurrence of broken and shell-less eggs. The incidence of shell-less eggs also increases with higher concentrations of NaC1 in the water. The use of saline drinking water with breeder flocks significantly reduces the production of day-old chicks through reduced numbers of settable eggs and lower hatchability. The primary metabolic lesion associated with the poor eggshell quality which results from the intake of saline drinking water appears to be related to the supply of bicarbonate rather than calcium to the lumen of the shell gland for eggshell formation. A reduced activity of carbonic anhydrase in the shell gland mucosa is of particular importance. This limits the supply of bicarbonate and the dependent calcium to the lumen of the shell gland. Treatments which have been found to be effective are preventive rather than remedial in nature. The two most promising treatments, apart from desalination of drinking water, appear to be the use of ascorbic acid supplements in the diet or drinking water appear to be the use of ascorbic acid supplements in the diet or drinking water and the use of zinc–methionine supplements in the diet. The mechanism by which ascorbic acid exerts its effect is unknown but the response is dose-dependent. The zinc component of zinc–methionine appears to be the important factor with this treatment, perhaps through its effect on carbonic anhydrase, a zinc-requiring enzyme.

Observations on the commercial production of ostrich (Struthio camelus) in the United Kingdom: rearing of chicks.

Two sets of ostrich eggs (60 and 120 eggs) were imported into the United Kingdom under class 1 quarantine restrictions. The eggs were incubated and observations were made on the growth, survival and sex ratio of the chicks hatched. The chicks decreased in weight for five days after hatching before they began a sustained period of exponential growth. They reached a liveweight of 4 kg five weeks after hatching. Female chicks grew significantly faster than male chicks. The survival rates of the chicks to three months of age were 66.7 per cent and 78.3 per cent, respectively, for the two sets of eggs, and mortality restricted mainly to the first four weeks of rearing. All the birds which died showed poor rates of growth before they died. The sex ratio of both groups was skewed 2:1 towards males.

Observations on the commercial production of ostrich (Struthio camelus) in the United Kingdom: incubation.

Two sets of ostrich eggs (60 and 120 eggs) were imported into the United Kingdom under class 1 quarantine restrictions. Single stage incubation was carried out and the eggs were weighed before and during incubation in order to control weight loss. In the two hatches the weight losses during the incubation of viable eggs were 13.4 per cent and 11.4 per cent, respectively. The development of the eggs was followed by candling and although only dark shadows were observed a pattern could be recognised. For the first set of eggs the average length of incubation was 45.9 days with an interval of 12.7 hours between pipping and hatching. The second set of eggs was incubated at higher temperatures than the first and the main incubation period was 43.3 days with hatching 19.2 hours after pipping. Larger eggs took longer to hatch.

The Relationship Between Body Weight and Reproductive Efficiency in Meat-Type Chickens

With improvements in growth rate of broiler chickens, the ability of meat-type parent stocks to reproduce has been severely reduced. Broiler breeder chickens require dedicated programs of feed restriction to maximize egg production and chick production. The production of settable eggs is limited by poor shell quality as a result of a lack of coordination of the shell calcification process, and by a high incidence of multiple-yolked eggs. The erratic nature of oviposition in full-fed hens, evidenced by multiple ovipositions in a 24-h period and by ovipositions occurring during the dark period, indicates that such hens do not abide by the principles of the ovulatory cycle that are accepted for egg-type hens. Fertility is reduced in overweight broiler breeders due to reduced mating success (which limits sperm transfer to the female), by a reduction in the duration of fertility, and possibly by impaired sperm transport to the site of fertilization (because the normal passage of developing eggs is more random than in egg-type hens). Fertility can also be poor due to problems with the male, including reductions in semen production and libido as well as poor physical coordination. Embryonic mortality is high in the eggs of overweight hens, as such eggs are often poorly calcified, which results in increased shell porosity and egg weight loss. Overweight hens exhibit short laying sequences and may also have poor overall chick production due to an increased incidence of first-of-sequence eggs, which have been demonstrated to exhibit an increased incidence of embryonic mortality.

Hatch of Eggs of Overwintering Blackheaded Fireworm (Lepidoptera: Tortricidae) in Response to Duration of Winter

Eggs of overwintering blackheaded fireworm, Rhopobota naevana (Hubner), were collected from cranberry marshes in Wisconsin and Washington. Eggs were held at a naturally progressing photoperiod (for 45 degrees latitude) and constant cold temperatures representing winter conditions in the two states: -2 degrees C for Wisconsin and 5 degrees C for Washington. On five different dates in March, April, and May, sets of eggs were incubated at 18 degrees C while natural photoperiod was maintained. The first three groups of eggs from Wisconsin showed no difference in development rate upon incubation. The fourth group, transferred about mid-April, developed faster than previous groups. The fifth group developed fastest. The first group of eggs from Washington, incubated in early March, developed slowest. The remaining groups, incubated about mid-March and thereafter, developed and hatched at the same, more rapid, rate.

Effect of Feed Allowance During Rearing and Breeding on Female Broiler Breeders.: 2. Ovarian Morphology and Production

The influence of feed allowance during rearing (4 to 18 wk) and breeding (18 to 62 wk) on ovarian morphology and egg production was examined. During rearing, beginning at 4 wk of age, 400 Indian River pullets that had been full-fed from 1 day of age either continued to be full-fed (F, n = 200) or were feed restricted (R, n = 200), following commercial practice. At 18 wk of age, 100 birds (within ±15% of the mean BW) in each of F and R rearing groups were further assigned to be full-fed (n = 50) or feed restricted (n = 50) during breeding. Thus, based on feed allowance during rearing and breeding, four treatment groups were formed (FF, FR, RF, and RR).Feed restriction during rearing significantly delayed oviduct development and age at sexual maturity (age at first egg). Compared with feed restriction during both rearing and breeding (RR), ad libitum feeding beginning at 18 wk of age (RF) significantly increased the weight of the ovary and the number of large follicles at sexual maturity but did not significantly affect the age at sexual maturity. Feed restriction during rearing, breeding, or both significantly reduced the incidence of erratic ovipositions, defective eggs, and multiple ovulations. The incidence of erratic ovipositions was positively correlated (r = .692, P ≤ .001) with the laying of soft-shelled and shell-less eggs and negatively correlated (r = −.508, P ≤ .001) with the production of settable eggs to 62 wk of age. Compared with ad libitum feeding, controlled feeding during breeding significantly improved both settable and total egg production. Among the four feeding regimens, Treatment RR resulted in the highest fertility and hatchability.

Research Note: Increased Growth of Chicks and Poults Obtained from Hens Injected with Jackbean Urease

Two experiments were conducted using 120 Single Comb White Leghorn (SCWL) hens and 40 turkey hens. Hens were randomly assigned to two treatments: those injected with urease and controls injected only with adjuvant. At 22 wk of age, half of the SCWL hens were injected intramuscularly with 12 Sumner units of jackbean urease suspended in incomplete adjuvant six times in 26 wk. Turkey hens were injected twice at weekly intervals with 70 Sumner units. The other half of the breeders received adjuvant without urease (control). Urease injection into SCWL hens had no effect on feed consumption, feed conversion, and percentage fertility, hatchability, and hatch of all eggs set, but egg weight and body weight of chicks at hatch and at 3 wk of age were significantly higher as compared with the control hens. In the case of turkey hens, percentage hatchability and progeny body weight were significantly higher as a result of urease injection.

The Influence of Egg Sequence Position on Fertility, Embryo Viability, and Embryo Weight in Broiler Breeders

A study was undertaken to determine whether fertility, early embryo viability, and the weight of the egg, shell, and embryo are influenced by the position of an egg in a laying sequence. One hundred and three Indian River broiler breeder hens were housed individually in cages at 21 wk of age. Beginning at 43 wk of age, each hen was inseminated once per week, with 50 μL of fresh undiluted pooled semen from Indian River broiler breeder males. Beginning at 45 wk of age, and for the following 45 days, all eggs laid were collected. Eggs were collected hourly for 8 h after “lights on” and a final daily collection was made 14 h after lights on. Each egg was classified as “first-of-sequence” or “subsequent”. Eggs were weighed and placed in a forced-air incubator twice per week. After 168 h of incubation, the eggs were removed from the incubator, weighed and assessed for fertility and embryo viability status. The embryo was also weighed. Shell weight was recorded after 3 to 4 days of air drying.Egg weight was significantly greater in first-of-sequence compared with subsequent eggs. First-of-sequence eggs exhibited significantly smaller Day 7 embryos (on a percentage basis), lower shell weight (on a percentage basis), and significantly less egg weight loss during the 7 day incubation period (absolute and percentage basis) than did subsequent eggs of a sequence. Least squares (LS) means for fertility did not differ significantly between first (87.02%) and subsequent (89.56%) eggs. There was no significant difference in LS means for embryo viability (number viable per 100 fertile eggs set × 100) between first (89.71%) and subsequent (92.75%) eggs. However, the number of viable embryos per 100 eggs set (fertility × viability) was significantly lower in first (78.74%) compared with subsequent (83.17%) eggs.

Key to the eggs of the equid stomach bot flies Gasterophilus Leach 1817 (Diptera: Gasterophilidae) utilizing scanning electron microscopy

Abstract. A key to the eggs of the equid stomach bot flies is presented. Scanning electron photomicrographs of eggs are used to illustrate differences among the eight Gasterophilus species. The eggs include those of G.haemorrhoidalis (Linnaeus, 1758), G.inermis (Brauer, 1858), G.intestinalis (De Geer, 1776), G.meridionalis (Piller and Evans, 1926), G.nasalis (Linnaeus, 1758), G.nigricornis (Loew, 1863), G.pecorum (Fabricius, 1794), and G.ternicinctus Gedoelst, 1912. The eggs of G.meridionalis and G.ternicinctus are shown for the first time. Egg profile is the same for a particular species and is used as a key character for egg identification. Colour of eggs is used in some couplets but only as a supplemental character. Absence or presence of striae on the eggs is used as a primary contrasting character to separate G.pecorum from the other seven species. Shape of the striae varies on eggs of the same species, even those dissected from the same specimen, and is therefore deemed an unreliable taxonomic character for further separation of the Gasterophilus species. Eggs of the same species taken from specimens throughout the world appear the same in profile. Two sets of eggs require close inspection for adequate identification: G.inermis and G.nigricornis separated primarily by the shape of the microphylar region; and G.intestinalis and G.ternicinctus separated by the shape of the egg ventrum. All other eggs have very unique and distinctive profiles. Only G.pecorum was found to possess the Type‐II egg attachment organ (AO) used for adherence of the egg to plants or flat surfaces. The eggs of the remaining seven species possess a Type‐I AO used to attach the eggs to hair shafts. The type of AO and the degree that the Type‐I AO is extended posteriorly were used as key characters in the first and second couplet respectively.

Reproductive Performance of Artificially Inseminated Hens Receiving Saline Drinking Water

Laying hens were selected at random and placed in individual cages in a commercial type layer shed. One hundred hens received town water and one hundred received town water supplemented with 2 g NaCl/L. Half the hens on each water treatment were inseminated every 7 days with mixed semen collected from six cockerels of a commercial table egg strain maintained on town water. The remaining hens were inseminated with semen from six cockerels receiving town water supplemented with 2 g NaCl/L. Eggs were collected and stored at 12 C over a 7-day period before eggs with defective shells were identified and removed. All remaining eggs were incubated and candled at 7 and 18 days of incubation to detect infertile eggs and embryonic deaths. Data from six consecutive hatches were analyzed.The incidence of eggs with defective shells doubled in hens receiving the saline drinking water. These hens had a significantly (twofold) higher incidence of embryonic deaths and a significantly lower (13%) hatchability of fertile eggs. For every 100 eggs laid the numbers of settable eggs and chicks hatched were significantly reduced in hens receiving the saline drinking water. The saline water reduced the numbers hatched by 20% for every 100 eggs laid. The water treatment given to the cockerels had little effect on reproductive performance.

Effect of low doses of gamma irradiation prior to egg incubation on hatchability and body weight of broiler chickens

1. Four experiments involving 23,800 settable eggs of commercial broiler parent stocks were conducted to determine the effect of gamma irradiation before egg incubation on hatchability and body weight of hatched chicks. 2. Irradiation doses were 0, 0.05, 0.10, 0.15, 0.20, 0.40, 0.80 and 1.2 Grays (Gy) for experiment 1; 0, 0.15 and 1.2 Gy for experiment 2; 0 and 0.15 Gy for experiment 3; 0, 1.6 and 2.1 Gy for experiment 4. Dose rate was about 0.12 Gy/min. 3. Gamma irradiation at doses of 0.05 to 1.6 Gy before incubation did not affect embryo development, whereas a dose of 2.1 Gy was harmful.

Biotin diffusion in stored chicken eggs: A re-assessment

1. 1. The possibility that biotin in stored eggs migrates from the yolk into the albumen was re-investigated. 2. 2. Sets of eggs collected from 12 Single Comb White Leghorn hens were stored at 5, 8, 12, 15, or 18°C for 5, 10, 15, 20, or 25 days and then frozen. 3. 3. For cach set, yolk and albumen samples adjacent to the yolk membrane were each pooled and assayed for protein-bound biotin by radioligand exchange with non-linear regression analysis of the data. 4. 4. In contrast to previous work reported by Bush and White ( Comp. Biochem. Physiol. 93B, 543–547, 1989), no evidence of biotin diffusion was found. 5. 5. Non-linear regression was used to re-evaluate the data from the earlier study, confirming the results, although less strikingly. 6. 6. The discrepancy is partly due to the method of data analysis, although differences in breed or number of hens may also be contributing factors.