Pre-laying Period Research Articles

Pre-Laying Nutrition of Sage Grouse Hens in Oregon

Diet, dietary selection, and nutritional composition of the food of sage grouse (Centrocercus urophasianus) hens were determined during the pre-laying period in southeastern Oregon in 1990 an 1991. We collected 42 female sage grouse during a 5-week period preceding incubation (4 March-8 April). Sagebrush (Artemisia spp.) was the most common among 21 foods consumed but forbs composed 18 to 50% of the diet by weight. Desert-parsley (Lomatium spp.), hawksbeard (Crepis spp.), long-leaf phlox (Phlox longifolia Nutt.), everlasting (Antennaria spp.), mountain-dandelion (Agoseris spp.), clover (Trifolium spp.), Pursh's milk-vetch (Astragalus purshii Dougl.), buckwheat (Eriogonum spp.), and obscure milk-vetch (A. obscurus) were the primary (greater than or equal to 1% of the diet by weight) forbs consumed. Forbs were used selectively over sagebrush in both low and big sagebrush cover types. All forbs were higher in crude protein and phosphorus and many were higher in calcium than sagebrush. Consumption of forbs increased nutrient content of the composite diet. Substantially fewer forbs were present in the diet in 1991 than in 1990, which coincided with reduced sage grouse productivity on the study area. These results suggest that consumption of forbs during the pre-laying period may effect reproductive success by improving nutritional status of hens.

Are Hazel Grouse Bonasa bonasia monogamous?

The apparently monogamous social organization of Hazel Grouse Bonasa bonasia previously had been inferred only from observations of unmarked birds. Using radio‐marked Hazel Grouse, we confirmed that the social organization during the breeding season was indeed monogamous, the pair being the social unit. The pair bond, however, appeared relatively weak, as birds were together only 37% of the time during the prelaying period. We could not document mating behaviour, but observations suggested that most males mated monogamously and that at least 37% of the females had an opportunity to mate polyandrously because of (1) the seemingly weak pair bond, (2) attentive neighbouring males, (3) larger territory size of unpaired males, (4) extensive movements of some unpaired males, (5) sharing of a female by two males and (6) a potentially male‐biased sex ratio.

The Relationship of Plasma Thyroid Hormone and Prolactin Concentrations to Egg Laying, Incubation Behavior, and Molting by Female Turkeys Exposed to a One-Year Natural Daylength Cycle

To determine relationships to egg laying, incubation behavior and molting, plasma thyroxine (T4), triiodothyronine (T3), and prolactin levels of 20 female domestic turkeys were determined throughout a one-year cycle of natural daylengths. Endocrine changes were analyzed relative to periods of reproductive and molting cycles. Data were also analyzed relative to termination of lay after division into two groups based on the presence (I, n = 7) or absence (NI, n = 13) of incubation behavior. Plasma T4 levels of the flock increased to a peak and subsequently decreased during the onset of lay period from February to April. Plasma T4 generally increased throughout the decline of lay period from April to July and molting period from July to October, and then reached greatest levels at the end of the molting period. Plasma T3 reached a peak early in the onset of lay and decreased rapidly during the remainder of that period. Plasma T3 remained depressed during the decline of lay, increased throughout molting, and attained greatest levels as molt was completed. Prolactin was low throughout the prelay period and sharply increased midway through the onset of lay. Prolactin increased to a marked peak during the decline of lay, and then rapidly decreased as egg laying was terminated. Relative to NI birds, egg laying was terminated earlier and prolaclin levels were markedly greater during and following the termination of lay in I birds. Plasma T4 and T3 were generally lower in I birds during the molting period which followed the termination of lay and their molt was delayed. These results support the hypothesis that changes in thyroid hormone and prolactin levels are involved in physiological processes associated with the termination of egg laying and molting in female turkeys.

Effect of Light Intensity Level During Prelay Light Restriction on Subsequent Reproductive Performance of Turkey Breeder Hens

Two trials were conducted to determine whether light intensity levels during the prelay (light restriction) and the lay (egg production) periods influenced subsequent photoinduced reproductive performance of turkey breeder hens. The light intensity levels were 22 and 270 lx and each was provided during the prelay and lay periods in a factorial arrangement. Each of the lay period light intensity levels were applied to half of the hens from each prelay treatment group. Data were collected for BW, rate of reproductive development, egg production, fertility, hatchability, egg weight, and poult weight.There were no interactions between the prelay and lay period treatments, nor a consistent prelay light intensity effect on rate of initiation of lay or duration of time to achieve 50% production. In addition, prelay and lay light intensity levels had no consistent effects on rate of lay, percentage of fertility and hatchability, egg weight, and poult weight. It was concluded that there was no advantage to the use of high-intensity light during short-day light restriction of the prelay period on subsequent reproductive performance.

Numbers and size of sperm storage tubules and the duration of sperm storage in birds: a comparative study

Estimates of the numbers of sperm storage tubules (SSTs) in the utero-vaginal junction of 11 bird species are presented. Numbers of SSTs varied by a factor of 40 between species, and ranged from 500 to 20000. Body mass accounted for over 50% of the variation in SST mumbers. SST length was positively correlated with the length of spermatozoa across species. The duration of sperm storage was not correlated with the number of SSTs or the volume of sperm storage tissue. However, the number of ‘active’ SSTs appears to vary between species and it was not possible to make allowance for this. Sperm storage duration was weakly, positively correlated wth clutch size, but showed a significant positive relationship with the number of days over which laying occurred. The number of SSTs was also positively correlated with the number of sperm per ejaculate. The best predictor of sperm storage duration was a multiple regression equation using the spread of laying and the length of sperm storage tubules. The duration of sperm storage in birds which remain together during the pre-laying period is such that a single insemination immediately before the start of laying could fertilize the entire clutch.

The Effects of Re-Seeding Heathland on Breeding Whimbrel Numenius phaeopus in Shetland. II. Habitat Use by Adults During the Pre-Laying Period

The Effects of Re-Seeding Heathland on Breeding Whimbrel Numenius phaeopus in Shetland. II. Habitat Use by Adults During the Pre-Laying Period

Female Feeding and Male Vigilance during Nesting in Greater Snow Geese

We studied the duration of the pre-laying period, female feeding activity, male vigilance, and the potential for parent-offspring conflicts in high-Arctic nesting Greater Snow Geese (Chen caerulescens atlantica). The pre-laying period is unusually long for a goose species nesting at high latitudes (73” N). Geese arrived at Bylot Island around 27 May but the peak initiation of egg-laying was around 12-14 June. During pre-laying, paired females fed for 75% and were alert for 6% of the 24-hr day, whereas males fed for 44% and were alert for 33% of the day. In one year that laying geese were observed, females fed less than during pre-laying and time spent at the nest increased. Time budget was not related to time of day or number of days before egg-laying. Although male vigilance apparently enabled females to devote more time to feeding, male alert behavior was poorly synchronized with female feeding. Pair copulations were recorded frequently (0.23/hr) and 2 extra-pair copulations were observed. Males were involved more often than females in aggressive interactions (2.55 vs. 0.36 aggressions bird-l hr-I) and often attacked neighboring pairs. The proportion of pairs with yearlings was low (6.3%) and parents frequently attacked their young (1.53 bird-’ hr-I). However, presence of yearlings did not influence time budget of pairs. The long pre-laying delay and the intense feeding activity of females suggest hat, in addition to energy reserves accumulated during the spring migration, food intake on the nesting ground may also be an important source of energy for laying Greater Snow Geese.

Sex Differences in Reproductive Behavior of Atlantic Puffins

Female Atlantic Puffins (Fratercula arctica) incubated eggs longer and fed chicks more often than males, whereas males spent more time maintaining and defending the nesting burrow. Although time together was greatest during the pre-laying period, pair members were apart most of the time, suggesting limited mate guarding. Males attempt extra-pair copulations, but because copulations occurred on the water where females can dive to escape, copulations were never forced and may have been successful only between mates. These data suggest that the paired female's ability and willingness to prevent mating with additional males may be important in the evolution of mate guarding. Sex differences in time budgets and male mating attempts were consistent with suggestions that even with shared parental care in monogamous species, females invest more in direct care of the young (parental effort), while males invest more in territorial defense and attempted extra matings (mating effort).

Experimental Evidence for Food Limitation of Egg Production in Gulls

Lesser Black-backed Gulls Larus fuscus nesting on Flat Holm Island in 1989 laid significantly smaller clutches than birds nesting in the same colony in the years 1983-86. Provisioning territories with supplementary food (fish) in 1989 during the prelaying period significantly increased clutch size and egg size compared with unfed controls. Similar experiments carried out on nearby Skomer Island in 1988, where egg production by unfed birds was typical of the species in Britain, did not increase clutch or egg size. The results clearly indicate that egg production can be limited by poor food supply during the laying period, but suggest that such food limitation is not a proximate mechanism for the restriction of the normal clutch to three.

Sexual selection and the tail ornaments of North American barn swallows

In this study conducted in southeastern Ontario, Canada, we manipulated the length of outer tail feathers (streamers) of male barn swallows (Hirundo rustica) shortly after they returned to four small breeding colonies in the spring. Both streamers on most males in these colonies were experimentally either lengthened or shortened by 20 mm and as a result 10 randomly chosen males of each category had their streamer lengths manipulated before the fertile period of their mate. Males with elongated streamers had a significantly shorter pre-laying period (from arrival until first egg date) than those with shortened streamers and we interpret this as indicating that they obtained their mates more rapidly. Females mated to elongated males had significantly longer tails and laid their first egg significantly earlier than those mated to shortened males; no other indices of reproductive success differed between these two experimental groups. These results provide some support for previous work suggesting that females prefer males with longer streamers and thus that streamer length in this species is under the influence of sexual selection. We also found that males with longer natural streamers were significantly more likely to break them and that males were much more likely to break their streamers than were females. Since males participate in incubation in North America but not in Europe, we suggest that the aerodynamic disadvantages of streamer breakage that result from incubation attentiveness are at least partly responsible for the shorter streamer length of males in North America.

BREEDING BIOLOGY OF THE BEARDED VULTURE IN SOUTHERN AFRICA, PART I: THE PRELAYING AND INCUBATION PERIODS

Summary Brown, C. J. 1990. Breeding biolo of the Bearded Vulture in southern Africa, Part I: The pre-laying and incubation periods. Ostrich 61: 24–32. In southern Africa the Bearded Vulture Gpaetus barbatus lays its eggs in mid-winter. between the second half of May and the first week of July. Pairs became more active in their nesting areas about six weeks before laying and usually roosted there at night. Courtship flights were less frequent and demonstrative than in Eurasian birds and took place mainly in the late afternoons. During the pre-laying period most nest visits (77%) were to bring nesting material, 92% by the male. All nesting material was arranged by the female. Copulation was always preceded by allopreening, and occurred most frequently in the mornings. No copulation or courtship display took place after the first egg had been laid. Of 18 clutches, 16 (89%) contained two eggs and the remainder one egg. The laying interval was usually 3–5 days (range 2–9 days). Incubation started with the firs...

Dietary Effects on Body Composition and Subsequent Production Characteristics in Broiler Breeder Hens

Broiler breeder pullets were fed either a broiler starter (23% CP, 3,133 kcal per kg) or pullet grower (15.5% CP, 2,885 kcal per kg) diet from 2 to 18 wk of age. Feed allocations were adjusted to equalize energy intake (kcal per day). Protein intake, however, was greater for pullets fed the starter diet versus those fed the grower diet A sample of pullets of similar BW from each treatment was killed at 13 and 18 wk of age. The starter diet resulted in a significant increase in the weight of the tibia and the associated muscles (total drumstick) and of the Pectoralis major (breast) muscle and a significant decrease in the size of the abdominal fat pad at both ages. During the prelay period (18 to 25 wk), half the pullets in each pullet treatment were fed either the pullet grower (LP) or broiler starter (HP) diet There were no significant effects of protein intake during the rearing or prelay periods on the aforementioned carcass parameters at 25 wk of age. The HP treatment resulted in a significant increase in hen-day production from 28 to 32 and from 32 to 36 wk of age. The LP treatment resulted in a nonsignificant increase in BW at 27 wk (P<.064) and in the number of double-yolked eggs from 32 to 36 wk (P<.096) relative to the HP treatment. Egg size was also increased nonsignificantly (P<.067) from 28 to 32 wk by the LP treatment relative to the HP treatment.

Effect of Body Weight, Feed Allowance, and Dietary Protein Intake During the Prebreeder Period on Early Reproductive Performance of Broiler Breeder Hens

In Experiment 1, two groups (n = 180) of breeder pullets were selected at 16 wk from two larger groups with BW of either 1,591 ± 43 (LBW) or 1,988 ± 59 g (HBW). From 16 wk of age until a peak feed allotment of 159 g per bird per day, weekly feed allowances were increased in a low (LOW), medium (MED), or high (HIGH) manner. There were significant differences (P<.05) in BW between the LBW and HBW treatments through 32 wk of age. Within each pullet weight class, the HIGH treatment was numerically heaviest through 32 wk. The HBW hens had significantly improved hen-day production from 24 to 28 (P<.001) and 28 to 32 wk (P<.06). The LOW treatment resulted in significantly poorer production in both the LBW and HBW weight groups from 24 to 28 wk. There were no significant treatment effects on egg weight at a given age. Within each pullet treatment, the HIGH treatment resulted in an increased percentage of double yolked (DY) eggs from 24 to 28 wk (P<.05) and 28 to 32 wk (P<.07).In Experiment 2, pullets in each of two pullet treatments received approximately 12 kg of feed from 2 to 24 wk of age. One treatment received a greater quantity of feed early in the rearing period (HEAVY) while pullets in the other treatment received a greater quantity of feed later in the rearing period (LIGHT). One-half of the pullets from each rearing treatment were fed either a 14% (LOWPRO) or 18% (HIGHPRO) protein diet during the prelay period (18 to 24 wk). Pullets in the HEAVY treatment were significantly heavier (P < .01) than those in the LIGHT treatment at 21 but not at 24 wk. The HIGHPRO treatment resulted in a significant improvement (P<.05) in hen-day egg production from 24 to 28 and 28 to 32 wk. There were no treatment effects on egg weight, and the LOWPRO treatment resulted in a significant increase (P≤.01) in the number of DY eggs from 28 to 32 wk.

The effect of food on laying date and clutch‐size in Tengmalm's Owl Aegolius funereus

The breeding of Tengmalm's Owl Aegolius funereus was studied at Umeå, Sweden, during the 1984–85. Mean clutch‐size was one egg larger in 1984 than in 1985 despite the later laying in 1984. The difference in clutch‐size was related to a better food supply in 1984. Daily weight increase of females during the prelaying period showed a high negative correlation with laying date in 1985, and a high positive correlation with clutch‐size independently of laying date in 1984–85. This suggested that food eaten before and during laying had a great and direct influence on both laying date and clutch‐size. Many females increased in weight during laying and most others decreased only moderately (relative to egg weight), suggesting that body reserves were not a main source for egg production.Late breeding females were provided with extra food during the prelaying and laying periods in 1985. Fed females weighed more, bred eight days earlier and laid one more egg than controls. At the same laying dates in mid season, and after heavy snow‐fall, clutch‐size and female weight were larger in the fed birds than in controls, but this was not so near the end of the laying season. Although the earliest of the fed late breeders weighed more, and probably were less restricted by food availability just before or during laying, they did not lay more eggs than did early breeders. This result suggested some limitation on clutch‐size that could not be overcome by the supplementary feeding. Weights of females during laying did not show any consistent relationship with clutch‐size during successive laying date intervals, suggesting that clutch‐size was not directly related to body condition.

Deceptive use of alarm calls by male swallows, Hirundo rustica: a new paternity guard

Male swallows (Hirundo rustica) frequently gave alarm calls when their fertile mates left the nest vicinity without the male during egg laying. Females engaged in extrapair copulations during such absences when they were not guarded intensely by their mates. However, males were sometimes able to disrupt extrapair copulation attempts toward their mates by giving alarm calls, causing all nearby swallows to take flight. I experimentally tested the idea that male swallows gave alarm calls when their certainty of paternity was at stake. When colonially breeding female swallows were temporarily chased away from their nest during the egglaying period in the absence of their mates, males nearly always gave alarm calls when they returned to the empty nest. In contrast, colonially breeding males rarely gave alarm calls when their mates were absent during the prelaying or the incubation periods. Solitarily breeding males rarely gave alarm calls in the absence of their mates, irrespective of the time in their nesting cycle. However, solitarily breeding males did give alarm calls when their mates were absent from the nest if a male mount previously had been presented near their nest during the egg-laying and the prelaying periods, but not during the incubation period. Deceptive use of alarm calls (in the absence of any predators) by male swallows apparently was an effective paternity guard.

Time Allocation by Northern Fulmars Fulmarus glacialis during the Breeding Season

Averaged over the whole breeding cycle (pre-laying through mid-chick stage), breeding fulmars spent about 39% of their time at the breeding site and 61% of their time at sea. Annual means of site occupancy before egg-laying were positively correlated with breeding success, suggesting that time allocation was a sensitive indicator of food availability in different years. Nonbreeding site-holders spent about half as much time at the colony as breeders; their attendance was highest early in the season when pair bonds and site ownership were established. The attendance of failed birds after egg or chick loss was positively correlated with colony-wide breeding success in six years. Males spent more time at the breeding site than females at every stage of the season. Most days were devoted to foraging in the pre-laying period (69% in males, 82% in females). An extended absence from the colony just before laying (the pre-laying exodus) averaged 12.2 d in males and 17.6 d in females. Changes in body weight indicated that neither sex incurred an energy deficit on a seasonal basis. A greater investment by the male in site attendance during incubation offset the female's investment in egg production and assured that both sexes entered the demanding chick-feeding stage in good condition.

Quantification of reproductive changes and nutrient requirements of broiler breeder pullets at sexual maturity

1. 480 Broiler breeder pullets, kept in individual cages, were subjected to different rates of increase in food allocation during the period 18 to 30 weeks of age. From 80 g food/bird d at the start of the experiment, the 5 treatments comprised linear weekly increments in food allocation to reach a maximum of 150 g/bird d at 21, 23, 25, 27 or 29 weeks of age respectively. 2. Body weight, liver weight, fat pad weight and alimentary tract weight were influenced by the rate of increment in food allocation. 3. Rate of development of the oviduct and the ovary was not influenced by these treatments. 4. Although the amount of fat and protein contained in the liver increased most rapidly on the treatments where 150 g/bird d was attained first, by 25 weeks of age there were no meaningful differences in these two variables between treatments. It is unlikely, therefore, that a high protein intake during this period would allow sufficient protein or energy to be stored in the liver to sustain a higher egg output later in the laying period. 5. It is concluded that the amount of protein required by a broiler breeder pullet for maintenance and for growth during the pre-laying period is about 10 g/bird d.

Severe Feed Restriction in Pullets During the Early Growing Period: Performance and Relationships Among Age, Body Weight, and Egg Weight at the Onset of Production

The performance of egg type (Leghorn × Rhode Island Red) chickens that were feed restricted during the prelaying period was studied in two trials, each conducted with 300 hens. In Trial 1, treatments included 1) an ad libitum-fed control; 2) restriction for close to zero growth between 7 and 28 days of age; 3) the same restriction as (2) but continued by restriction of 50% growth up to 70 days; 4) restriction between 7 and 70 days for 50% growth; and 5) restriction for 50% growth between 7 and 98 days. In Trial 2, birds were restricted severely (close to zero growth) from 7 to 28 days of age, followed by restriction of 50% growth up to 28, 56, 84, and 112 days of age, respectively.In all cases, feed restriction resulted in a delay in the onset of egg production, leading to some increases in egg weight. Egg production rate and cumulative production were not affected, in most cases, by early feed restriction. The BW at the onset and after 20 mo of production was reduced when feed restriction was continued beyond the age of 84 days. Overall feed conversion (grams feed per egg) and feed efficiency (grams feed per gram egg mass) were not affected significantly by feed restriction, although feed efficiency (grams gain per gram feed) was improved during the prelaying period. Within each treatment, BW was positively correlated with age at onset of egg production. Egg weight was a function of both age and BW at the onset of production. The significant correlation between egg weight and BW was maintained even after a year of production.

Sperm Competition and Copulation Intervals of the White Spoonbill (Platalea leucorodia, Aves, Threskiornithidae)

AbstractSome aspects of sperm competition were studied in the white spoonbill (Platalea leucorodia) breeding in Doñana National Park (SW Spain). Shorter pair copulation intervals occurred during the prelaying period, when females were subjected to a relatively high frequency of extra‐pair copulations. Pair copulation intervals with an intermediate extra‐pair copulation by the male mate were longer than those without extra‐pair copulation. This result indicates that males need a time of recovery between copulations before they can perform another. Extra‐pair copulations by the females did not affect the length of intervals between pair copulations. There were no differences between the lengths of the intervals between an extra‐pair copulation by the female and the following pair copulation for cases in which the male mate detected an intruder male attempting copulation with his mate and those in which the intruder remained undetected. However, the correlations obtained between copulatory intervals for detected and undetected cases suggest a copulatory response by their mates, although affected by the required recovery time between copulations by the males. Finally, since extra‐pair copulations mainly occurred while male mates were collecting nest material, they engaged in this activity shortly after pair copulations, probably to avoid a last‐male advantage under the sperm competition pressure.

Turkey hen fertility and egg production after artificial insemination and multiple oviduct eversion during the pre-laying period.

The onset of egg production (mean 18.3 days after the onset of photostimulation) and the rate of egg production (flock averaged 4.9 eggs per bird per week for the first 8 weeks of egg production) were not affected by 5 days of twice daily oviduct eversion ('venting') in the pre-laying period when compared to unvented controls. After the onset of photostimulation, pre-laying hens were inseminated twice daily on Days 12 to 16 with 3 microliter semen containing 15 x 10(6) spermatozoa, and compared with groups of hens inseminated once daily on Days 15 and 16 with 15 microliters semen containing 75 x 10(6) spermatozoa or 41 microliter semen containing 200 x 10(6) spermatozoa. Fertility remained high for the first 5 weeks of egg production. However, by Week 6 the fertility of the hens receiving frequent low doses of semen dropped significantly below that of the others, which suggests that multiple inseminations with a low semen volume containing relatively low numbers of spermatozoa does not lead to an increase in the efficacy of sperm transport and storage in the oviduct.