Pre-breeding Period Research Articles

Conspecific cues and breeding territory selection in Whinchat on abandoned fields

Many bird species use social information to guide territory selection. Different species in different habitats may use both pre-breeding and post-breeding conspecific cues. Abandoned agricultural fields are of particular interest for studies of conspecific attraction because the ephemeral nature of the habitat suggests territory search just before breeding, but high predation pressure suggests the use of performance-based conspecific cues. We investigated whether post-breeding or pre-breeding social cues affect Whinchat (Saxicola rubetra) abundance at the territorial scale during a two-year experiment in abandoned fields. We assigned 27 experimental plots (3.14 ha) to one of three treatments: post-breeding treatment, pre-breeding treatment and silent control. We conducted playback experiments with fledgling calls (evidence of past reproductive success) during the post-breeding period and male songs (evidence of conspecific presence) during the pre-breeding period. We estimated the difference in Whinchat abundance in two consecutive years and tested whether this value differed between treatment and control plots. We observed a slight increase (0.67 ± 0.29 pairs per plot) in Whinchat abundance in the post-breeding treatment plots and no significant changes in the pre-breeding (−0.22 ± 0.32 pairs per plot) and control (−0.22 ± 0.22 pairs per plot) plots. Our results suggest that Whinchats do not use conspecific acoustic cues during the pre-breeding period and provide limited evidence for the use of fledgling calls as conspecific cues in the post-breeding period.

Arrival-breeding interval is flexible in a songbird and is not constrained by migration carry-over effects.

As spring phenology advances with climate change, so too must the timing of life cycle events. Breeding at the right time is critical in many species as it maximizes fitness. For long-distance migratory birds, flexibility in the duration of the arrival-breeding interval (pre-breeding period) may allow populations to adjust their timing of breeding. However, whether first egg-lay dates are flexible to local environmental conditions after arrival, and if they are constrained by the time needed to replenish energy lost during migration, remains unclear. We investigated the regional flexibility of the arrival-breeding interval in an avian migrant, the purple martin, Progne subis, across their breeding range. We evaluated whether the duration of the arrival-breeding interval was flexible to temperature and precipitation at breeding sites, and if timing was limited by migration rate and stopover duration. We also tested if longer interval durations were associated with higher fledging success. To address our hypotheses, we used a combination of migration tracking, weather and breeding data collected from four regions across eastern North America (26.1° N to 52.4° N latitude). We found the arrival-breeding interval to be shortest in the north and longest in the south. Across all regions, warmer temperatures encountered at breeding grounds were associated with shorter intervals, and faster migration rates led to longer intervals. The length of the interval was not influenced by precipitation or stopover duration. Finally, longer intervals were not associated with higher fledge success. Currently, the longer arrival-breeding intervals in this study system, on average 28.3 days, may provide both early and late-arriving birds with ample time for recovery so birds can lay eggs according to temperature. Any negative effects of faster migration may have been buffered by longer arrival-breeding intervals, as interval length did not determine fledge success. With ongoing climate change, further research is needed to examine if arrival-breeding intervals become constrained by migration timing, which may limit opportunities for migrants to match the timing of breeding with key resources.

326 Relationship between activity and social interactions of beef bulls during the pre-breeding period and siring capacity in multi-sire breeding groups

Abstract It is currently unknown whether the behavior of bulls during pre-breeding is related to their siring capacity. This information could help producers anticipate the reproductive potential of their bulls and include it in their decision-making. This study aimed to investigate the relationship between the activity and characteristics of social interaction of beef bulls expressed in drylot pens during the pre-breeding period and their siring capacity. Collars with 3-axis accelerometers and proximity sensors were placed on bulls for 12 d prior to breeding season in 2020 (n = 11 bulls) and in 2021 (n = 10 bulls). Bulls were satisfactory at the breeding soundness evaluation, and ages ranged from 1.5 to 5.4 yr. Afterward, bulls were exposed to cows in multi-sire groups at a 1:30 ratio for 2 mo, however, some bulls were removed early due to injuries (range = 15 to 62 d). DNA samples were collected from bulls and calves to calculate the number of calves sired per bull (SRC), adjusted to days exposed to cows. Daily proportion of time active (AC) was measured through a machine learning algorithm created in Python for beef bulls to differentiate activity vs. non-activity from accelerometer data every 20 sec (Precision = 95%). Daily non-directional social networks were created from proximity perceived by the sensors (Precision = 91%, <3m) in Python, where nodes represented bulls and a connection represented one second in proximity. Eigencentrality (how well connected a bull is to others, EC) and strength (proportion of connections among overall connections, ST) were calculated for each bull daily, where greater EC and ST values indicated more interactions. The statistical analyses were performed in RStudio. Negative binomial mixed effect models were fitted to AC (mean ± S.E., 26.05 ± 0.31 %), EC (26.50 ± 0.89), and ST (8.90 ± 0.21 %) as repeated measures, age (3.3 ± 0.3 yr), days exposed to cows (54 ± 3.1 d), and year as covariates, identification of bull as a random effect, and SRC as the outcome variable (21 ± 2, 2 to 45 calves). Estimates were transformed into percentage change. Days exposed to cows, year, and interactions were not significant (P > 0.05). Separate models with EC or ST (model-EC and model-ST) were built due to collinearity (r = 0.89, P < 0.001). In model-EC (marginal-R2 = 0.26, conditional-R2 = 0.70) bulls with increased AC (estimate = 2.16±0.67, P = 0.001), increased EC (0.56±0.24, P = 0.019), and younger (-20.75 ± 5.51, P < 0.001) had greater SRC. In model-ST (marginal-R2 = 0.25, conditional-R2 = 0.72) bulls with increased AC (2.29 ± 0.65, P < 0.001), increased ST (3.57 ± 0.98, P < 0.001), and younger (-19.90 ± 5.49, P < 0.001) had greater SRC. These preliminary results suggest that activity and social interactions during pre-breeding of beef bulls are related to SRC when accounted for age. Therefore, the behavior of beef bulls during the pre-breeding period might have the potential to predict their SRC, and future studies could investigate using this information to select bulls and form breeding groups aiming at optimization of the use of the bulls.

Seasonal changes in invertebrate diet of breeding black-necked cranes (Grus nigricollis).

Invertebrates greatly support the growth, development, and reproduction of insectivorous birds. However, the influence of human activity (e.g., pesticide use, deforestation, and urbanization) inevitably leads to a decrease in global arthropods. The diversity and variation in invertebrate diet influence the food composition of birds, especially species living in rapidly changing environments, such as the Tibetan Plateau. However, little is known of the seasonal variation in invertebrate diet in response to environmental changes. Here, we characterized the invertebrate diet composition in pre- and post-breeding black-necked crane (Grus nigricollis) using fecal metabarcoding. We identified 38 invertebrate genera; the top three were Tipula (82.1% of relative abundance), Ceramica (3.0%), and unclassified_Hymenoptera (2.5%), with Tipula predominated the diet in both seasons. We also observed 20 and 16 unique genera in the pre- and post-breeding periods, and the genera composition was distinct between seasons (R = .036, p = .024). In pre-breeding, black-necked cranes tended to consume more diverse foods, and individual cranes exhibited greater heterogeneity at the genus level. At the genera and species level, pre-breeding black-necked cranes showed a wider dietary niche than post-breeding cranes. We observed season-specific features, with Tipula (common crane fly) and Stethophyma (grasshoppers) being enriched in the post-breeding period and Ceramica (moth) being more abundant in the pre-breeding period. Three Tipula species had the greatest importance in discriminating between seasonal diets. This study demonstrated a seasonal pattern of invertebrate diet in the black-necked crane, suggesting diet composition in response to resource and species availability. These results elaborate on the foraging ecology of highland birds and can inform the management of black-necked crane conservation.

Effect of supplementing algae to breeding and early gestation first calf heifers on growth and reproduction.

Fat supplementation has potential to improve reproductive performance and increase pregnancy rates in cattle by increasing the energy density of the diet. However, some of the positive effects of fat seem to be influenced by the type of fatty acid fed. Docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) are long-chain n-3 poly-unsaturated fatty acids (PUFA) that have important biological effects on reproduction through their involvement in hormone and series 3 prostaglandin synthesis. Ruminant tissues are naturally almost devoid of n-3 long-chain PUFA, specifically EPA and DHA. Algae biomass provides a consistent source of DHA and EPA that could be fed to alter hormonal profiles and improve reproduction of beef heifers. Eighty-eight Angus × Simmental heifers (427 ± 1.8kg body weight [BW]) were blocked by BW and allotted to 2 treatments (44/treatment, 4 pens/treatment, 11 heifers/pen). Control heifers were fed a diet that contained (dry matter [DM] basis) 52.8% mixed grass silage, 32% corn silage, and 15.2% concentrate. DHAgold (49% fat; 21.8% DHA; DSM Inc.) was included in the algae diet at 1.65% DM, replacing equal parts of corn and DDGS. Diets were formulated to contain 12% crude protein and 0.85 Mcal/kg net energy for gain (NEg). Heifers were fed treatment diets from 54 d prior to the breeding season through the first trimester. Follicular fluid was collected on day 47 for hormonal analysis. Artificial insemination (AI) was from days 54 to 77. Heifers that did not get pregnant to AI were removed from the study on day 109 and placed with a bull. The study ended on day 180. Data were analyzed using the MIXED procedure of SAS. During the pre-breeding period, algae heifers had lesser dry matter intake (P = 0.006) compared to control heifers. Heifers supplemented with algae had a greater average daily gain (P = 0.03) during the breeding period and BW tended (P = 0.06) to be greater for algae compared to control heifers on day 98 and was greater on day 180 (P = 0.03). Dominant follicle diameter and follicular estrogen concentration were unaffected by treatment (P ≥ 0.12). Follicular insulin-like growth factor-1 was greater in algae compared to control heifers (P = 0.03). First service conception rate did not differ between treatments (P = 0.67); however, second service and overall conception were lesser (P ≤ 0.03) in algae compared to control heifers. These data suggest supplementing DHA-rich algae improved growth but decreased conception rates of primiparous beef females.

37 Precision Feeding of Prolific Sheep in Highly Productive Management Systems

Abstract Globally lamb production is constrained by seasonal reproduction and flock productivity. There is potential to reduce both with improved reproductive and nutritional management in systems with a reduced interbirth interval. These accelerated systems can improve productivity >2 times compared with conventional systems. Successful adoption of these systems has been hampered; however, by low and variable reproductive efficiency during the suboptimal breeding period (February to July). We designed a series of studies to address this problem using an 8-month birth interval system with Polled Dorset x Polypay ewes without the use of exogenous hormone or photoperiod therapies. In study 1, we examined prebreeding nutrition combined with the male effect on reproductive outcomes in both long (April/May) and short-day (Dec./Jan.) breeding seasons. Ewes were randomly allocated to one of 3 nutritional treatments after weaning during a 21-day prebreeding period: 50%, 100% or 200% of maintenance energy intake. Ewes were exposed to vasectomized rams the last 14 days of treatment followed immediately with fertile rams for a 34-day breeding period (22 to 27 ewes per vasectomized or fertile ram). Both litter size (1.60 short vs. 1.34 long) and conception (96% short vs. 86% long) were greater in the short season (P < 0.001). Nutrition did not impact conception in either season; however, litter size was increased 15% in long and 25% in short day breeding season in ewes fed 200% compared the other treatments. These results suggest that litter size can be improved in these systems regardless of season by elevating energy intake above current recommendations. In study 2, we examined the impact of energy status during 2 preconception periods: lactation (last 30 days of previous lactation) and flushing (21 days pre-breeding plus 34-day breeding period). During lactation ewes received either 70% (L), 100% (C), and 150% (H) of energy requirements according to litter size. During flushing, ewes received 70%, 100% and 160% of maintenance energy with reproductive management as for study 1. Blood samples collected every 3 to 4 days were analyzed for plasma progesterone concentration via radioimmunoassay. Season had a great impact on return to estrus with 18% of ewes exhibiting luteal phases before teaser ram introduction during long as compared with 99% during short-day season. Nutrition during lactation also impacted return to estrus but only in long days with 40% of ewes on the H diet exhibiting luteal phases compared with 14% on the L diet before teaser ram introduction. Collectively, this indicates that an increased rate on conception is possible without the use of exogenous hormones or photoperiod manipulation in accelerated systems. Furthermore, a high plane of preconception nutrition improves litter size regardless of season and may hasten return to estrus during the suboptimal breeding period.

Comparative studies on ovary and serum hormone levels in silver and blue foxes and their hybrids

The silver and blue fox appear closely related despite their belonging to different genera, and the male and female fox hybrids are completely sterile in mating inter se or back to either of the parental groups. In the present study, we compared ovarian morphology and serum hormone concentrations among silver foxes, blue foxes, HSBs (silver fox male × blue fox female hybrids) and HBSs (blue fox male × silver fox female hybrids) during the pre-breeding and the breeding period. We found that either the fertile blue and silver foxes or the infertile hybrid foxes showed typical characteristics of ovary, with primordial, primary, secondary, antral and Graafian follicles. The diameters and quantities of different follicle classes in fertile foxes were greater than that in hybrids during the two period, while the thickness of zona pellucida (ZP) represented an opposite trend (P < 0.05). The relative weight of bilateral ovaries in fertile foxes was greater than that in hybrids during the pre-breeding period, while mean serum FSH represented an opposite trend during the breeding period (P < 0.05). The mean serum estradiol in fertile foxes was greater than that in HBS foxes during the pre-breeding period, and greater than hybrids during the breeding period (P < 0.05). These findings indicated that in the infertile hybrid foxes, lower estradiol levels produced by lesser and smaller antral follicles, thicker ZP during the two period, higher FSH levels during the breeding period, could be the basis of interpretations in cases of female fox hybrid infertility.

Features of the biochemical profile of blood in the pre-breeding period in breeding goats with various manifestations of sexual reflexes during the breeding season

Serum biochemical analysis is a valuable diagnostic tool to evaluate the metabolic and health status of animals. Сcompared with females, the relationship between biochemical components of blood and the effectiveness of the male reproductive system have been poorly understood. The aim of the work was to determine the biochemical blood profile before the start and at the peak of the breeding season in male Saanen goats with differences in the manifestation of sexual behavior. Blood sampling from animals (n = 16) was carried out twice: before the start of the breeding season (4th week of July) and at the peak of the breeding season (4th week of September). In the blood serum, the concentration of total protein, albumin, urea, creatinine, glucose, total cholesterol, total bilirubin was determined, as well as the activity of enzymes: aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP). At the end of the observation period, the animals were divided into groups: group I (n=10) - males with a full manifestation of sexual reflexes when taking sperm and group II (n=6) - individuals with incomplete manifestation of sexual reflexes. The biochemical profile of blood had features in males with differences in the manifestation of sexual behavior. At the peak of the breeding season in group I compared to group II in the blood of animals, the concentration of creatinine, triglycerides and total bilirubin increased by 37.4%, 170%, 48.3%, respectively (at least p&lt;0.05). Before the mating period, the content of total bilirubin in the blood in group II was 63.9% higher than in group I (p&lt;0.01) and 12.1% higher than the upper limit of the reference interval. We assume that an increase in the concentration of total bilirubin in the blood of males in the pre-mating period above the boundary of the reference interval is negatively associated with the full manifestation of sexual reflexes in the breeding season.

Influence of Seasonal and Monthly Variation on Blood Serum Total Protein in Ctenopharyngodon idella

This study is serum protein of Ctenopharyngodon idella higher in breeding period. That value in post breeding slightly lower and pre–breathing less more than post breeding season in male. In female serum protein where higher in the post breeding. In the breeding season the serum protein is slightly lower and pre breeding value of serum protein less than breeding period.&#x0D; The mean values of female were higher in the post breathing period 5.65 gm% showing seasonal variation as 4.8 to 6.5 gm%. In the breeding season the mean value were very slightly lower side as were found in post breeding season, this period the mean value were 5.50±0.07gm% with seasonal variation of 4.4 to 6.9gm%. During summer pre breeding period the mean values 4.82±0.05 gm % with there seasonal variation of 4.0 to 5.7 gm%. In Male were higher breeding period as 5.65± 0.03 gm% showing seasonal variation as 4.5 to 6.3 gm %. In post breeding season the mean value was very slightly lower side as were found in breeding season in this period the mean value were 5.62±0.06 gm% with the seasonal variation of 4.5 to6.6gm%. During summer i.e. pre breeding period the mean value were 4.62±0.05gm% with their seasonal variation of 3.2 to5.6 gm%.

Effects of the Level and Composition of Concentrate Supplements before Breeding and in Early Gestation on Production of Different Hair Sheep Breeds.

Female hair sheep, 27 Dorper (DOR), 41 Katahdin (KAT), and 39 St. Croix (STC), were used to determine influences of the nutritional plane before breeding and in early gestation on feed intake, body weight, body condition score, body mass indexes, blood constituent concentrations, and reproductive performance. There were 35 multiparous and 72 primiparous sheep, with initial ages of 5.6 ± 0.25 years and 1.5 ± 0.01 years, respectively (average overall initial age of 2.8 ± 0.20 years). Wheat straw (4% crude protein; dry matter [DM] basis) was consumed ad libitum and supplemented with approximately 0.15% initial body weight (BW) of soybean meal (LS) or a 1:3 mixture of soybean meal and rolled corn at 1% BW (HS; DM). The supplementation period was 162 days, with the breeding of animals in two sets sequentially, with the pre-breeding period 84 and 97 days, and that after breeding began at 78 and 65 days, respectively. Wheat straw DM intake (1.75, 1.30, 1.57, 1.15, 1.80, and 1.38% BW; SEM = 0.112) was lower (p < 0.05), but average daily gain (-46, 42, -44, 70, -47, and 51 g for DOR-LS, DOR-HS, KAT-LS, KAT-HS, STC-LS, and STC-HS, respectively; SEM = 7.3) was greater (p < 0.05) for HS than LS treatment during the supplementation period. Additionally, changes in body condition score during the supplementation period (-0.61, 0.36, -0.53, 0.27, -0.39, and -0.18; SEM = 0.058), and changes in body mass index based on height at the withers and body length from the point of the shoulder to the pin bone (BW/[height × length], g/cm2) from 7 days before supplementation (day -7) to day 162 were -1.99, 0.07, -2.19, -0.55, -2.39, and 0.17 for DOR-LS, DOR-HS, KAT-LS, KAT-HS, STC-LS, and STC-HS, respectively; (SEM = 0.297) were affected by supplement treatment. All blood constituent concentrations and characteristics addressed varied with the day of sampling (-7, 14, 49, 73, and 162) as well as the interaction between the supplement treatment and the day (p < 0.05), with few effects of interactions involving breed. Birth rate (66.7, 93.5, 84.6, 95.5, 82.8, and 100.0; SEM = 9.83) and individual lamb birth weight (4.50, 4.61, 4.28, 3.98, 3.73, and 3.88 kg; SEM = 0.201) were not affected by supplement treatment (p = 0.063 and 0.787, respectively), although litter size (0.92, 1.21, 1.17, 1.86, 1.12, and 1.82; SEM = 0.221) and total litter birth weight (5.84, 5.74, 5.92, 7.52, 5.04, and 6.78 kg for DOR-LS, DOR-HS, KAT-LS, KAT-HS, STC-LS, and STC-HS, respectively; SEM = 0.529) were greater (p < 0.05) for HS than for LS. In conclusion, although there was some compensation in wheat straw intake for the different levels of supplementation, soybean meal given alone rather than with cereal grain adversely affected BW, BCS, BMI, and reproductive performance, the latter primarily through litter size but also via a trend for an effect on the birth rate. Hence, the supplementation of low-protein and high-fiber forage such as wheat straw should include a consideration of the inclusion of a feedstuff(s) high in energy in addition to nitrogen.

Non-breeding movements of the Black-tailed Gull (Larus crassirostris)

With the continued development of tracking technology and increasing interest in animal movement, our understanding of migration behavior has become more comprehensive. However, there are still many species that have not been well studied, particularly sea birds. Here, we present the first year-round Global Positioning System (GPS) tracking data of the Black-tailed Gull (Larus crassirostris) at the population level. We used solar-powered GPS-Global System for Mobile communication (GSM) loggers to successfully track 30 individuals breeding at Xingrentuo Islet, Liaoning Province, China, for 1–3 years. Except for one individual who roamed in the far north of the Yellow Sea during non-breeding period, all others did a directed southward migration. Migration routes and wintering sites differed among migrating gulls and between years for the birds tracked for two or more years. Additionally, during wintering, the migrating gulls were more likely to travel over a large body of water and shift sites, and some trajectories were quite complex, which was probably closely related to what we observed in the field about their boat-chasing behavior. Compared to wintering movements, the post-breeding movements ranged over a smaller area. Specifically, almost all of them had a long post-breeding period near the breeding islet (≥120 days, <220 ​km from the breeding islet), and 80% of the gulls who were tracked more than one year had at least one faithful post-breeding site. Compared to the post-breeding period, only approximately half of the migrating gulls had a pre-breeding period that was shorter (3–20 days) and closer to the breeding islet (≤80 ​km). Migration distance varied among migrating gulls (range 209–2405 ​km) and the gulls moved least distance during post-breeding period. Furthermore, we found that the southward movement of the migrating gulls occurred when the temperature near the breeding islet dropped; specifically, the gulls directly migrated southward away from the post-breeding site. Our results suggest that the Black-tailed Gull has a long post-breeding period but a short pre-breeding period near the breeding islet and high diversity of their migrating patterns (in especial migration routes and wintering sites).

Effect of supplementation of polyunsaturated fatty acid-rich linseed grain on steroid hormones and reproduction in Goats

The effect of polyunsaturated fatty acid (PUFA)- rich linseed grain supplementation was assessed on steroid hormones and reproduction in goats. Twenty-four acyclic and clinically healthy non-descript goats were divided into 4 equal groups. Gr A(control) was supplemented with concentrate without linseed grain while Gr B, C and D were supplemented with concentrate containing 10, 15 and 20% of linseed grain respectively. Goats were supplemented during prebreeding period for 30 days. Blood samples were collected for estimation of serum estradiol and progesterone during pre-breeding and post-oestrus periods. Serum estradiol concentration (pg/ml) was significantly (P<0.05) higher in Gr B (58.79±3.62), C (70.34±5.95) and D (49.48±5.02) compared to control Gr A (38.51±4.03) on 30 days of pre-breeding period. It was significantly (P<0.05) lower in Gr B (9.61±1.45) compared to A (15.61±2.65), C (12.61±1.35) and D (12.61±2.65) on 7 days of post-oestrus period. Serum progesterone levels were comparable among the groups on 30 days of pre- breeding and on 7 days of post- oestrus period. Blood glucose level was comparable on 21 days of supplementation in pre-breeding and 0 day of postoestrus period. Conception (83.33%) and kidding (83.33%) rates were higher in Gr B compared to control Gr A (50.00 and 33.33%). The study suggested that supplementation of PUFA-rich linseed grain in concentrate @ 15% decreased the serum estradiol and increased the serum progesterone during post-oestrus period and improved the conception and kidding rates in goats.

Improving beef calf health: frequency of disease syndromes, uptake of management practices following calving, and potential for antimicrobial use reduction in western Canadian herds.

Bovine respiratory disease (BRD), calf diarrhea (CD), and navel infections are the most commonly reported diseases of western Canadian beef calves. The objectives of this study were to estimate the frequency of treatment for these diseases for specific age cohorts and identify potential opportunities for reducing antimicrobial use. Producers representing 89 western Canadian cow-calf herds completed a survey describing calfhood diseases and management. The most common reason for calf treatment before weaning was BRD (4.9%), and BRD treatment was described in 51% of reporting herds before 2 months of age. Calf diarrhea (2.9%) and navel infection (2.0%) were the second and third most common reasons for treatment. Most calves were treated for CD between 6 days and 1 month of age. Almost one in five herds reported routinely administering antimicrobials at birth. Calving heifers and cows together were all associated with an increased treatment risk for BRD in calves from birth to 2 months (OR 3.55, 95%CI 2.13-5.94, P < 0.0001), CD from 1 month to weaning (OR 3.94, 95%CI 1.29-12.0, P = 0.02), and navel infection (OR 4.55, 95%CI 1.78-11.6, P = 0.002). Failure to sort cow-calf pairs out of the calving area was also associated with an increased treatment risk for BRD from 4 months to weaning (OR 4.89, 95%CI 1.96-12.2, P = 0.0006) and CD from 24 h to 5 days (OR 2.82, 95%CI 1.03-7.75, P = 0.04), and not using the Sandhills system was associated with an increased treatment risk for navel infection (OR 4.55, 95%CI 1.78-11.6, P = 0.002). Other potentially modifiable factors associated with an increased risk of BRD in calves from birth to 2 months were winter feeding and calving in one area (P < 0.0001), heifers calving in a higher density area (P = 0.01), and an increasing number of times cow-calf pairs were gathered before turn out to summer pasture (P = 0.0005). The purchase of any cows during the calving or prebreeding period was associated with an increased risk of BRD from birth to 2 months (P < 0.0001) and from 2 to 4 months (P < 0.0001). A history of respiratory bacterin vaccines administered to the dams was associated with a decreased risk of BRD in calves from 4 months to weaning (P = 0.01). Cows calving in a higher density area was associated with an increased risk of CD from 1 month to weaning (P = 0.02). These practices present opportunities for investigation of approaches to disease management that could support the judicious use of antimicrobials.

A lifelong floater: the Red Kite female that never met a mate

ABSTRACT The Red Kite Milvus milvus is endemic to the western Palearctic. While the largest breeding population is in Germany, the population density decreases substantially from central to eastern Europe. In 2015, we tagged two young Red Kite females with telemetry loggers in an area with very low kite density in the northeastern part of Slovakia. One of these females failed to breed over her seven-year lifespan. After leaving her post-fledging area she never returned. During her first two years, she undertook two exploratory flights to Croatia and Romania, but remained exclusively in southwestern Slovakia and northeastern Hungary over the rest of her life. Throughout this period, she always wintered alone and no other Red Kites were ever observed in her wintering grounds. During the pre-breeding period (March–April), she remained outside the area that held breeding kite pairs, and there were no signs of breeding based on her positions during the breeding season. This seven-year-old is the oldest Red Kite floater recorded to date. Owing to the low density of Red Kite breeding pairs in Slovakia and Hungary, it is likely that she was unable to find a suitable mate prior to the beginning of the breeding season. In such areas, the role of floaters may prove critical for the persistence of low-density Red Kite populations.

Plasma levels of luteinizing hormone and prolactin in relation to double brooding in Great Tit (Parus major)

The reproductive behaviors of birds are mainly controlled by the hypothalamus-pituitary-gonad axis. Many studies have shown that reproductive hormones are tightly linked to the breeding sub-stages. However, only a few studies have examined the temporal trend of hormone levels among different reproductive stages in multiple brooded species. We investigated the changes in plasma luteinizing hormone (LH) and prolactin (PRL) concentrations during different reproductive stages of the facultative double-brooded Great Tit (Parus major). We found that the concentrations of LH and PRL in females were significantly higher than those in males. Females had significantly higher LH and lower PRL concentrations in the pre-breeding period than in the first/second brooding periods, and there were no significant changes between the first and second brooding periods. The concentrations of LH and PRL in males had no significant difference between the pre-breeding period and the first brooding periods, while LH and PRL concentrations in the second brooding period were significantly higher than those in the first brooding period. We conclude that there are sex-based differences between LH and PRL at different stages of reproduction. The changes in LH and PRL in both males and females should be related to their physiological functions. Especially for males, individuals with higher levels of LH and PRL are more likely to maintain second clutches.

Body condition and molt chronology of waterfowl in east central Texas

Waterfowl undergo changes in body condition during migratory and wintering periods that can affect survival and reproduction. Understanding how condition varies among age and sex cohorts and temporally can inform habitat management during the post- and pre-breeding period. We examined changes in body composition and molt of three waterfowl species migrating and wintering in managed moist-soil units in east central Texas and determined the influence of season, age, and sex using Analysis of Variance. We examined age, sex, and season effects on body condition indices (body mass divided by wing chord) using mixed-effects models and determined the influence of molt score on body condition using linear regression. For specimens collected from 2004–2007, we found differences in body composition among age and sex groups for Blue-winged Teal (<em>Spatula discor</em>), a migrant through this study area, and for Green-winged Teal (<em>Anas crecca</em>), and Northern Shoveler (<em>Spatula clypeata</em>), which are wintering species. We found a mid-winter decline in body condition for Green-winged Teal. Blue-winged Teal were in worse condition in spring than in fall, which could be due to differences in energy accumulation prior to departure to wintering grounds in fall and post-arrival in spring. We did not find an effect of season for Northern Shoveler. For all species, adults were in better condition than juveniles. Molt score was greatest in late-winter for all species combined (x̄ = 11.60, SE = 2.45). We did not find an effect of molt score on body condition for any species. Wintering waterfowl in east central Texas appear to be in good condition and did not show molt-induced stress during the migratory and wintering periods. Changes in condition among specimens and across seasons indicate that there should be consideration in the timing and quality of management in regional approaches to moist-soil management for migrating and wintering waterfowl.

Histological Investigation of Cyclic Variation in Secretory Activity of Seminal Vesicles in Emballonurid Bat, Taphozous kacchensis (Dobson)

The present study describes the cyclical changes in the secretory activity of the seminal vesicle in the emballonurid bat, Taphozous kacchensis. The secretory activity in the seminal vesicles during the quiescence cycle was not well marked in T. kacchensis. During the sexually quiescent period (May to August), seminal vesicles were regressed, the tubules were lined by cuboidal to low columnar epithelial cells with round to elongated darkly stained basally to centrally placed nuclei. Cytoplasm was basophilic containing fine or coarse secretory granules in the cytoplasm. The lumina of the tubules were devoid of secretion. During the pre-breeding (September to January) period, the tubules were enlarged and were lined by tall columnar epithelial cells with large spherical basally situated nucleus. The secretory blebs were seen arising from the apical surface of the cells and were seen releasing into the lumen. Lumina of the tubules were filled with homogenous eosinophilic secretion. During the breeding period (February to March), the seminal vesicle showed hypertrophy resulting in the increase in the tubular diameter as compared to that of quiescent period. The epithelial lining of the tubules was cuboidal with centrally placed nuclei. The tubular lumina were full of homogenous secretion during active pre-breeding and breeding period as the secretory material released into the lumen by both apocrine and merocrine modes. Regressive changes in the seminal vesicle were evident from April. The tubules showed gradual hypotrophy as the quiescent period approaches in May.

Sympatrically breeding congeneric seabirds (Stercorarius spp.) from Arctic Canada migrate to four oceans.

Polar systems of avian migration remain unpredictable. For seabirds nesting in the Nearctic, it is often difficult to predict which of the world's oceans birds will migrate to after breeding. Here, we report on three related seabird species that migrated across four oceans following sympatric breeding at a central Canadian high Arctic nesting location. Using telemetry, we tracked pomarine jaeger (Stercorarius pomarinus, n = 1) across the Arctic Ocean to the western Pacific Ocean; parasitic jaeger (S. parasiticus, n = 4) to the western Atlantic Ocean, and long‐tailed jaeger (S. longicaudus, n = 2) to the eastern Atlantic Ocean and western Indian Ocean. We also report on extensive nomadic movements over ocean during the postbreeding period (19,002 km) and over land and ocean during the prebreeding period (5578 km) by pomarine jaeger, an irruptive species whose full migrations and nomadic behavior have been a mystery. While the small sample sizes in our study limit the ability to make generalizable inferences, our results provide a key input to the knowledge of jaeger migrations. Understanding the routes and migratory divides of birds nesting in the Arctic region has implications for understanding both the glacial refugia of the past and the Anthropocene‐driven changes in the future.

Difference in Body Weight at Breeding Affects Reproductive Performance in Replacement Beef Heifers and Carries Consequences to Next Generation Heifers.

Simple SummaryThe effect of prebreeding feeding to attain 55% vs. 65% of mature cow body weight (MBW; 545 kg) at breeding on the reproductive performance of beef heifers and its offspring was investigated. Angus-cross dam heifers from weaning were randomly fed to attain 55% (n = 1622) vs. 65% (n = 1578) of MBW and off-spring (F1) heifers born to dam heifers in both 55% (n = 1285) vs. 65% (n = 1324) groups were fed to attain 65% of MBW. Results showed that restricted feeding negatively affected puberty, breeding season pregnancy and 21-day calving rates. F1 generation heifers that were fed normal diets but were born to dams that were fed restricted diets also had reduced puberty, breeding season pregnancy and 21-day calving rates. In conclusion, restricted feeding during the prebreeding period of dam heifers reduced post-pubertal fertility and fertility of their heifer offspring that were fed normal prebreeding diets.Nutrition imprinting carries consequences across generations. The effect of 55% vs. 65% of mature cow body weight (MBW; 545 kg) at breeding on the reproductive performance of heifers and their offspring was investigated. Angus-cross dam heifers were randomly fed to attain 55% (n = 1622) vs. 65% (n = 1578) of MBW, and offspring (F1) heifers born to dam heifers [55% (n = 1285) vs. 65% (n = 1324)] were fed to attain 65% of MBW. Bodyweight and reproductive indices were recorded throughout the study. In dam heifers, puberty (44% vs. 53%), breeding season pregnancy (86.4% vs. 90.6%) and 21-day calving rates (55.2% vs. 65.4%) did vary, but dystocia rate (8.7% vs. 9.0%) did not differ between 55% and 65% MBW groups. Puberty (49.2% vs. 58.2%), breeding season pregnancy (87.2% vs. 92.8%) and 21-day calving rates (53.8% vs. 64.1%) did differ (p < 0.05), but dystocia rate (8.4 vs. 9.2%) did not differ between F1 heifer groups. In conclusion, 55% of MBW at breeding negatively affected the reproductive performance of heifers and its offspring heifers. The recommendation is to feed heifers a balanced diet to reach 65% of MBW at breeding with consideration of production traits.

Pre-breeding androgen and glucocorticoid profiles in the eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis)

Seasonally breeding species exhibit cyclical changes in circulating steroid hormone profiles that correspond with changes to their reproductive behavior and ecology. Such information is critical to the conservation of imperiled and data-deficient species, such as the eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis). We determined changes in plasma testosterone (T), dihydrotestosterone (DHT), 11-ketotestosterone (11-KT), 11-ketoandrostenedione (11-KA), dehydroepiandrosterone (DHEA), cortisol, corticosterone, and progesterone (P4) during a four-month period preceding breeding in adult male and female eastern hellbenders. This pre-breeding period is characterized by increased diel movement and aggression by both sexes, follicular development and yolk production in females, and sperm production, territoriality, and nest site establishment in males. In both males and females, we observed a progressive increase in circulating T and DHT during the pre-reproductive season, both peaking in August (17 days before breeding), but concentrations of both hormones were higher in males. Conversely, 11-KT was higher in females, but did not vary significantly by date. These results suggest that T and DHT are the predominant androgens in eastern hellbenders and are likely important regulators of reproductive processes in both males and females. The detection of significant quantities of DHT and 11-KT in females is particularly interesting, considering that unlike T, neither of these androgens can be converted to estrogens. Therefore, it seems possible that aggression or some aspect of reproduction in the female eastern hellbender may be directly mediated by androgen signaling. Baseline cortisol did not vary throughout the pre-breeding period but was higher in females than males, and also became highly variable in females leading up to breeding. Progesterone, 11-KA, DHEA, and corticosterone were rarely or never detected, and thus, do not appear to be important during the pre-reproductive season. This study provides a physiological framework for future studies of hellbender reproductive biology, which could ultimately be important for their conservation.