Transcriptome Profiling Unveils Key Genes Regulating the Growth and Development of Yangzhou Goose Knob.

Goose is one of the most economically valuable poultry species and has a distinct appearance due to its possession of a knob. A knob is a hallmark of sexual maturity in goose (Anser cygnoides) and plays crucial roles in artificial selection, health status, social signaling, and body temperature regulation. However, the genetic mechanisms influencing the growth and development of goose knobs remain completely unclear. In this study, histomorphological and transcriptomic analyses of goose knobs in D70, D120, and D300 Yangzhou geese revealed differential changes in tissue morphology during the growth and development of goose knobs and the key core genes that regulate goose knob traits. Observation of tissue sections revealed that as age increased, the thickness of the knob epidermis, cuticle, and spinous cells gradually decreased. Additionally, fat cells in the dermis and subcutaneous connective tissue transitioned from loose to dense. Transcriptome sequencing results, analyzed through differential expression, Weighted Gene Co-expression Network Analysis (WGCNA), and pattern expression analysis methods, showed D70-vs.-D120 (up-regulated: 192; down-regulated: 423), D70-vs.-D300 (up-regulated: 1394; down-regulated: 1893), and D120-vs.-D300 (up-regulated: 1017; down-regulated: 1324). A total of 6243 differentially expressed genes (DEGs) were identified, indicating varied expression levels across the three groups in the knob tissues of D70, D120, and D300 Yangzhou geese. These DEGs are significantly enriched in biological processes (BP) such as skin morphogenesis, the regulation of keratinocyte proliferation, and epidermal cell differentiation. Furthermore, they demonstrate enrichment in pathways related to goose knob development, including ECM-receptor interaction, NF-kappa B, and PPAR signaling. Through pattern expression analysis, three gene expression clusters related to goose knob traits were identified. The joint analysis of candidate genes associated with goose knob development and WGCNA led to the identification of key core genes influencing goose knob development. These core genes comprise WNT4, WNT10A, TCF7L2, GATA3, ADRA2A, CASP3, SFN, KDF1, ERRFI1, SPRY1, and EVPL. In summary, this study provides a reference for understanding the molecular mechanisms of goose knob growth and development and provides effective ideas and methods for the genetic improvement of goose knob traits.

Comparative transcriptomic analyses reveal key genes underlying melanin distribution during embryonic development in geese (Anser anser).

1. Melanin distribution typically exhibits a gradient dilution along the dorsal-ventral axis of the body, including in domestic geese. However, the specific genes and molecular mechanisms responsible for this melanin distribution pattern remain incompletely understood.2. The transcriptomic comparisons were conducted at three embryonic stages, specifically on embryonic d 15 (E15), 22 (E22), and 29 (E29), between the pigmented dorsal skin and the depigmented distal foot.3. Differentially expressed genes (DEGs) associated with melanin synthesis were identified, particularly TYR, TYRP1, and EDNRB2, which exhibited significantly higher expression levels in the dorsal skin at E15 and E22. However, expression levels significantly decreased in later stages (E29).4. The ASIP gene showed remarkably high-expression levels in the distal feet compared to the dorsal skin post-E22 stage (log2FC: 5.31/6.88 at E22/E29). Gene Ontology (GO) enrichment analysis detected eight terms associated with melanin synthesis and melanosome formation (p < 0.05), including melanosome membrane (GO: 0033162) and melanin biosynthetic process (GO: 0042438). Additionally, KEGG pathway analysis showed significant enrichment of the melanogenesis pathway (hsa004916) at d 22 (E22).

Comprehensive analysis of lncRNAs, miRNAs and mRNAs related to thymic development and involution in goose.

Thymic involution is a sign of immunosenescence, but little is known about it in goose. miRNAs and lncRNAs are critical factors regulating organ growth and development. In this study, we comprehensively analyzed the profiles of lncRNAs, miRNAs and mRNAs during the development and involution of the thymus in Magang goose. The results showed that 2436 genes, 16 miRNAs and 417 lncRNAs were differentially co-expressed between the developmental (20-embryo age, 3-day post-hatch and 3-month age) and degenerative (6-month age) stages. The functional analysis showed that these differentially expressed genes were significantly enriched in cell proliferation, cell adhesion, apoptotic signaling pathway, and Notch signaling pathway. In addition, we established a gene-gene network through the STRING database and identified 50 key genes. Finally, we constructed a miRNA-mRNA network followed by a lncRNA-miRNA-mRNA network. These results suggest that lncRNAs and miRNAs may be involved in the regulation of thymic development and involution in goose.

Hypothalamus-pituitary axis transcriptomic modification dependent on growth rate in geese (Anser anser domesticus).

The hypothalamus-pituitary axis is involved in digest processing, stress response, energy storage and many other processes. In birds, this control differs from in mammals, such as regulation of appetite and satiety centre. The transcriptomics analyses of both brain structures can explain and identify the molecular processes related to body growth and development and nutritional status. Many reports describe chicken transcriptome in literature, but gene expression studies in the other poultry species are extremely rare. Therefore, the present research undertook the attempt to explain hypothalamus-pituitary processes in domestic geese-Polish White Koluda®, main Polish line. After 16 weeks of fattening, significant differences in geese weight were observed. Therefore, transcriptome of pituitary and hypothalamus profiles could be compared between low and high growth rate geese groups. Due to the lack of domestic geese genome assembly in the public databases, we used three mapping approaches: de novo analysis, mapping to two other pink-footed and swan geese genomes. The functional examination showed that the most enriched biological process in the geese hypothalamus covered the immune response. Moreover, in the hypothalamus, proteins typical for the pituitary such as PRL and GH were differentially expressed (DE). Our study recommends one gene as a candidate for growth rate in geese-the FOS gene, which encodes Fos proto-oncogene-DE in both analysed tissues. The FOS gene is involved in regulating feeding behaviour, immune regulation, stimulating cellular proliferation and controlling growth hormone synthesis. Moreover, the present investigation indicates DE genes involved in gene expression regulation. The study delivers new information about the changes in the pituitary-hypothalamic axis in geese dependent on growth rate differences.

The effect of different dietary levels of sodium and chloride on performance and blood parameters in goslings (1-28 days of age).

A total of 702 1-day-old male Jiangnan White goslings were used to study the effects of varying levels of Na+ and Cl- on their growth performance and blood parameters. In this experiment, goslings were randomly allotted to nine treatments, with six pens per treatment in a 3 × 3 factorial arrangement, and fed diets with three concentrations of added Na+ (0.10%, 0.15% and 0.20%) and three concentrations of added Cl- (0.15%, 0.20% and 0.25%). The purpose of this experiment was to investigate the sensitivity of goslings to Na+ and Cl- during brooding to determine the appropriate levels of Na+ and Cl- in their feed. The results are as follows: (a) Different levels of Na+ and Cl- in the diet, especially low Na+ and Cl- , significantly affected the body weight (BW), average daily gain (ADG) and feed/gain ratio (F/G) of the 28-day-old goslings (p < .05). But Na+  × Cl- has no significant effect on water consumption (p > .05). (b) Serum concentrations of urea increased linearly with Na+ content (p < .05). Serum concentrations of creatinine (CR) and uric acid (UA) increased linearly with Cl- content (p < .05). (c) Na+  × Cl- has a significant impact on the serum sodium (Na) and chlorine (Cl; p < .05). The content of serum Na and Cl increased linearly with increasing levels of Na+ and Cl- . These results show that low levels of Na+ and Cl- had significant adverse effects on the growth of 1- to 28-day-old goslings. The results of the experiment support a recommendation to supplement the diet of goslings with 0.20% Cl- and not <0.15% Na+ .

Effect of dietary Moringa stem meal level on growth performance, slaughter performance and serum biochemical parameters in geese.

Moringa stem meal (MSM) with a high level of crude fibre (CF) might be developed and utilized in herbivorous geese as an unconventional feedstuff. The aim of this study was to investigate the effect of the MSM level in the diet on the growth performance, slaughter performance, breast meat quality and serum biochemical parameters in geese from 22 to 70 days of age. A one-factor completely randomized design was adopted in our study. A total of one thousand eight 21-day-old geese were randomly divided into six groups, with six replicates per group and 28 birds per replicate. The geese were fed diets containing MSM levels of 0, 20, 40, 60, 80 or 100 g/kg during day 22-70. The dietary MSM level had no effect (p > .05) on the final body weight (BW), average daily gain (ADG) or average daily feed intake (ADFI). The feed/gain ratio (F/G) increased linearly (p < .001) as the dietary MSM level increased. No differences (p > .05) were observed in the slaughter performance, meat quality and the relative organ weight (except for thymus) of the geese (p > .05). The relative weight of the thymus in the geese fed diets with supplementation of MSM was higher than that in the non-supplemented MSM control group (p < .05). In addition, 100 g MSM/kg of diet decreased the serum glucose (GLU) level (p < .05) and increased the alanine transaminase (ALT) enzyme activity (p = .03). Dietary MSM levels of no more than 60 g/kg had no effects on the growth performance and slaughter performance, whereas diets with 100 g MSM/kg increased the F/G and serum ALT enzyme activity, as well as decreasing the serum GLU level. Therefore, MSM provided at a reasonable level could be developed as an unconventional feedstuff for geese at the finisher period.

Spring temperature, migration chronology, and nutrient allocation to eggs in three species of arctic-nesting geese: Implications for resilience to climate warming.

The macronutrients that Arctic herbivores invest in their offspring are derived from endogenous reserves of fat and protein (capital) that females build prior to the period of investment or from foods they consume concurrently with investment (income). The relative contribution from each source can be influenced by temporal and environmental constraints on a female's ability to forage on Arctic breeding areas. Warming temperatures and advancing Arctic phenology may alter those constraints. From 2011 to 2014, we examined relationships among spring temperature, timing of migration and reproduction, and the sources of nutrients females deposited in eggs for three sympatric species of geese that nested in northern Alaska. Compared to lesser snow geese (Anser caerulescens caerulescens) and greater white-fronted geese (Anser albifrons frontalis), black brant (Branta bernicla nigricans) were more likely to initiate follicle development during migration, resulting in fewer days between their arrival in the Arctic and the onset of incubation and requiring a relatively greater capital investment in eggs. Delaying follicle development until after their arrival in the Arctic provided snow geese and white-fronted geese an opportunity to forage near their nesting area and to deposit exogenous nutrients in eggs. With warmer spring temperatures, brant invested more capital in eggs, but snow geese invested less capital. Brant likely used capital to meet costs associated with earlier onset of follicle development when phenology was advanced, whereas snow geese used capital to compensate for poor foraging conditions during colder Arctic springs. Global warming is likely to reduce the quality of lower latitude marine habitats where brant acquire endogenous reserves and advancing Arctic phenology may increase their reliance on those reserves during reproduction. Near-term warming in northern Alaska may improve foraging conditions and favor the reproductive strategies of some herbivores such as snow geese and white-fronted geese that mainly invest Arctic nutrients in their offspring.

Flight feather moult drives minimum daily heart rate in wild geese.

Waterfowl undergo an annual simultaneous flight-feather moult that renders them flightless for the duration of the regrowth of the flight feathers. In the wild, this period of flightlessness could restrict the capacity of moulting birds to forage and escape predation. Selection might therefore favour a short moult, but feather growth is constrained and presumably energetically demanding. We therefore tested the hypothesis that for birds that undergo a simultaneous flight-feather moult, this would be the period in the annual cycle with the highest minimum daily heart rates, reflecting these increased energetic demands. Implantable heart rate data loggers were used to record year-round heart rate in six wild barnacle geese (Branta leucopsis), a species that undergoes a simultaneous flight-feather moult. The mean minimum daily heart rate was calculated for each individual bird over an 11-month period, and the annual cycle was divided into seasons based on the life-history of the birds. Mean minimum daily heart rate varied significantly between seasons and was significantly elevated during wing moult, to 200 ± 32 beats min-1, compared to all other seasons of the annual cycle, including both the spring and autumn migrations. The increase in minimum daily heart rate during moult is likely due to feather synthesis, thermoregulation and the reallocation of minerals and protein.

Production traits of artificially and naturally hatched geese in intensive and free-range systems: I. Growth traits.

1. This study investigated the effect of incubation type and production system on geese growth traits. 2. A total of 216 geese were either naturally (114) or artificially (102) hatched and reared in intensive or free-range production systems (4 replicates each) until 18 weeks of age. 3. Weights of naturally hatched goslings (NHG) were significantly higher than artificially hatched goslings (AHG) at 2 weeks (644 vs. 536 g); however, weights of AHG were significantly higher than NHG at both 6 weeks (3245 vs. 3010 g) and 18 weeks (5212 vs. 4353 g). 4. AHG had better feed conversion ratios (FCRs) than NHG (6.21 vs. 6.46 at 18 weeks). Feed consumption of naturally hatched geese was found higher in first 4 weeks when compared to artificially hatched geese and artificially hatched geese consumed more feed than naturally hatched geese after 8 weeks. 5. Production system had insignificant effects on feed consumption, FCRs, viability and mutilation rates. 6. Slipped wings were more frequent in NHG than AHG (8.32% vs. 1.68% at 6 weeks; 23.84% vs. 5.12% between 7 and 18 weeks) and in free-range production when compared to intensive production (17.88% vs. 11.08% over the course of the production period). 7. The study results indicate that both artificially and NHG can be reared in free-range production systems without any loss in performance and in deference to animal welfare.

Effects of forage feeding versus grain feeding on the growth performance and meat quality of Yangzhou geese.

1. Highly palatable and nutritious meat products can be produced through dietary interventions. Previous studies have shown that forage feeding has a significant impact on the growth performance and nutrition of cattle in various regions, but whether the same effects can be induced in geese remains unclear. 2. Three hundred and sixty Yangzhou goslings were divided according to body weight at 29 d old, assigned to one of 4 treatments and raised in separate pens. The treatments applied were (A) grazing, (B) grazing, grain supplemental diet (64 to 70 d), (C) grazing, grain supplemental diet and (D) confined. 3. Eviscerated carcass yield was lower in the grazing treatment. Protein content and muscle collagen in both the breast and thigh muscles were significantly higher in the grazing treatment than the confined, while fat content exhibited the opposite tendency. Those fed on grass and supplementary grain had a higher Mg and Cu content in breast muscle. 4. Geese will grow to their full potential when they are allowed to consume grass from pasture supplemented with grain, protein, collagen, Mg and Cu content was greater to a degree, which suggests this feeding regime is an ideal model for goose production.

Production traits of artificially and naturally hatched geese in intensive and free-range systems - II: slaughter, carcass and meat quality traits.

1. This study investigates the slaughter, carcass and meat quality traits of artificially and naturally hatched geese in intensive and free-range production systems. 2. The study was conducted with 114 naturally hatched and 102 artificially hatched geese. From each replicate of the intensive and free-range systems, one female and one male goose were slaughtered at the ages of 14, 16 and 18 weeks (a total of 32 geese per slaughter week). 3. Artificially hatched geese had higher slaughter weights (5280 vs. 4404 g), carcass weights (3520 vs. 2863), dressing percentages (66.6-65.2% vs. 65.0-63.6%) and carcass part, feather and edible inner organ weights. The ratio of both edible inner organs and abdominal fat was higher in naturally hatched geese. Breast meat L*, a* and pH values and thigh meat dry matter values were higher in artificially hatched geese, whereas thigh meat b* and pH values were higher in naturally hatched geese. 4. Intensively reared geese had higher slaughter weights (4900 vs. 4783 g), carcass weights (3253 vs. 3130 g) and abdominal fat weights (280 vs. 250 g), as well as higher dressing percentages (66.3-64.9% vs. 65.3-63.9%). Breast meat b* and thigh meat L* values were higher in the intensive system, while breast and thigh pH values, dripping loss and cooking loss were higher in the free-range system. Water-holding capacity was higher in the intensive system. 5. In conclusion, artificially hatched, intensively reared geese had the highest slaughter weights; however, both artificially and naturally hatched geese raised in a free-range system reached acceptable slaughter weights and can thus be recommended for use with this type of production system.

Paired box 7 (Pax7) gene: molecular characterisation, polymorphism and its association with growth performance in goose (Anser cygnoides).

1. Paired box (Pax7) gene is a member of the paired box family and plays a critical role in animal growth and muscle development. However, the molecular characterisation of the goose Pax7 gene is unknown. 2. The open-reading frame of goose Pax7 is composed of 1509 bp, which encodes a protein of 503 amino acids and shares high homology with Pax7 of other birds. 3. Ten single-nucleotide polymorphisms were identified in the genomic DNA sequence, 8 located in the intron region and two located in the exon region. 4. Association analysis showed the C122T locus was significantly associated with the body weight of Zhedong-White geese in week 4, 6, 8, 10 and 12. 5. It was concluded that the goose Pax7 gene may be an important candidate gene for goose growth traits and marker-assisted selection.

Altitude matters: differences in cardiovascular and respiratory responses to hypoxia in bar-headed geese reared at high and low altitudes.

Bar-headed geese (Anser indicus) fly at high altitudes during their migration across the Himalayas and Tibetan plateau. However, we know relatively little about whether rearing at high altitude (i.e. phenotypic plasticity) facilitates this impressive feat because most of what is known about their physiology comes from studies performed at sea level. To provide this information, a comprehensive analysis of metabolic, cardiovascular and ventilatory responses to progressive decreases in the equivalent fractional composition of inspired oxygen (FiO2 : 0.21, 0.12, 0.09, 0.07 and 0.05) was made on bar-headed geese reared at either high altitude (3200 m) or low altitude (0 m) and on barnacle geese (Branta leucopsis), a low-altitude migrating species, reared at low altitude (0 m). Bar-headed geese reared at high altitude exhibited lower metabolic rates and a modestly increased hypoxic ventilatory response compared with low-altitude-reared bar-headed geese. Although the in vivo oxygen equilibrium curves and blood-oxygen carrying capacity did not differ between the two bar-headed goose study groups, the blood-oxygen carrying capacity was higher than that of barnacle geese. Resting cardiac output also did not differ between groups and increased at least twofold during progressive hypoxia, initially as a result of increases in stroke volume. However, cardiac output increased at a higher FiO2  threshold in bar-headed geese raised at high altitude. Thus, bar-headed geese reared at high altitude exhibited a reduced oxygen demand at rest and a modest but significant increase in oxygen uptake and delivery during progressive hypoxia compared with bar-headed geese reared at low altitude.

Response of growing goslings to dietary supplementation with methionine and betaine.

An experiment with a 2 × 3 factorial design with two concentrations of dietary betaine (0 and 600 mg/kg) and three dietary concentrations of methionine (0, 600 and 1200 mg/kg) was conducted using goslings to estimate growth, nutrient utilisation and digestibility of amino acids from 21 to 70 d of age. Three hundred geese were randomised at 18 d of age into 6 groups with 5 replicates per treatment and 10 geese per replicate. Increasing dietary concentrations of methionine gave a linear increase in body weight and average daily gain. The coefficient of crude fat retention increased as dietary methionine increased and there was a significant non-linear response to increasing dietary methionine. Similarly, increasing supplemental methionine gave linear increases in the digestibility of methionine and cysteine. The results of this study indicated that optimal dietary supplementation of methionine could increase growth performance and methionine and cysteine utilisation in growing goslings. Betaine supplementation had no apparent sparing effect on methionine needs for growth performance, but did improve the apparent cysteine digestibility.

Trophic mismatch and its effects on the growth of young in an Arctic herbivore.

In highly seasonal environments, timing of breeding of organisms is typically set to coincide with the period of highest resource availability. However, breeding phenology may not change at a rate sufficient to keep up with rapid changes in the environment in the wake of climate change. The lack of synchrony between the phenology of consumers and that of their resources can lead to a phenomenon called trophic mismatch, which may have important consequences on the reproductive success of herbivores. We analyzed long-term data (1991-2010) on climate, plant phenology and the reproduction of a long-distance Arctic migrant, the greater snow goose (Chen caerulescens atlantica), in order to examine the effects of mismatched reproduction on the growth of young. We found that geese are only partially able to adjust their breeding phenology to compensate for annual changes in the timing of high-quality food plants, leading to mismatches of up to 20 days between the two. The peak of nitrogen concentration in plants, an index of their nutritive quality for goslings, occurred earlier in warm springs with an early snow melt. Likewise, mismatch between hatch dates of young and date of peak nitrogen was more important in years with early snow melt. Gosling body mass and structural size at fledging was reduced when trophic mismatch was high, particularly when the difference between date of peak nitrogen concentration and hatching was >9 days. Our results support the hypothesis that trophic mismatch can negatively affect the fitness of Arctic herbivores and that this is likely to be exacerbated by rising global temperatures.

Ecological implications of reduced forage quality on growth and survival of sympatric geese.

Allometric constraints associated with digesting leaves require relatively small avian herbivores to consume high-quality forage. How such constraints are overcome during ontogeny when energy and nutrient requirements are relatively high has not been adequately explored. We compared growth trajectories of Canada and lesser snow goose goslings raised on grass-based diets that differed in protein (10%, 14% or 18%) and fibre (30% or 45%) with those of free-living goslings on Akimiski Island, Canada. This common-garden experiment allowed us to test the hypotheses that (i) smaller-bodied geese are more negatively affected by reduced forage quality than larger-bodied geese, and (ii) goslings from subarctic brood-rearing areas have a limited capacity to slow growth in response to reduced forage quality. Canada goose goslings fed low-protein (10%) diets were on average 44% lighter in body mass, had slower growth rates and were delayed >20 days in reaching 90% of asymptotic size compared with Canada goose goslings fed 18% protein. In contrast, snow goose goslings were unable to survive on the low-protein diets, and those fed high- or medium-protein diets grew at a similar rate and achieved similar asymptotic size. Canada and snow goose goslings fed low-protein diets had reduced growth rates of the tarsus and delayed emergence of the 9th primary. Free-ranging Canada goslings on Akimiski Island were similar in mass and structural size to captive-reared goslings fed low-protein diets. In contrast, snow goslings were similar in mass and structural size to the captive-reared goslings fed the high- and medium-protein diets. This suggests that degraded habitats with mostly low-protein forage may be able to support Canada goslings better than snow goslings which require higher-quality forage to survive. Size-related differences in gosling growth and survival in response to diminished diet quality may influence population size when available food reaches a lower threshold in protein content. However, goslings can avoid such density-dependent population regulation if they are able to move their broods and find adequate quality and quantity of forage.

Transcriptome Analysis and Identification of Differentially Expressed Transcripts of Immune-Related Genes in Spleen of Gosling and Adult Goose.

The goose (Anser cygnoides), having high nutritional value, high-quality feathers and high economic benefit, is an economically important poultry species. However, the molecular mechanisms underlying the higher susceptibility to pathogens in goslings than in adult geese remains poorly understood. In this study, the histological sections of spleen tissue from a two-week-old gosling and an adult goose, respectively, were subjected to comparative analysis. The spleen of gosling was mainly composed of mesenchyma, accompanied by scattered lymphocytes, whereas the spleen parenchyma was well developed in the adult goose. To investigate goose immune-related genes, we performed deep transcriptome and gene expression analyses of the spleen samples using paired-end sequencing technology (Illumina). In total, 50,390 unigenes were assembled using Trinity software and TGICL software. Moreover, these assembled unigenes were annotated with gene descriptions and gene ontology (GO) analysis was performed. Through Kyoto encyclopedia of genes and genomes (KEGG) analysis, we investigated 558 important immune-relevant unigenes and 23 predicted cytokines. In addition, 22 immune-related genes with differential expression between gosling and adult goose were identified, among which the three genes showing largest differences in expression were immunoglobulin alpha heavy chain (IgH), mannan-binding lectin serine protease 1 isoform X1 (MASP1) and C-X-C chemokine receptor type 4 (CXCR4). Finally, of these 22 differentially expressed immune-related genes, seven genes, including tumor necrosis factor receptor superfamily member 13B (TNFRSF13B), C-C motif chemokine 4-like (CCL4), CXCR4, interleukin 2 receptor alpha (IL2RA), MHC class I heavy chain (MHCIα), transporter of antigen processing 2 (TAP2) IgH, were confirmed by quantitative real-time PCR (qRT-PCR). The expression levels of all the candidate unigenes were up-regulated in adult geese other than that of TNFRSF13B. The comparative analysis of the spleen transcriptomes of gosling and adult goose may promote better understanding of immune molecular development in goose.

Effect of different fibre sources on performance, carcass characteristics and gastrointestinal tract development of growing Greylag geese.

1. The effects of different fibre sources on the growth performance, carcass characteristics and gastrointestinal tract development were studied in growing Greylag geese (Anser anser). 2. Four experimental diets were formulated with corn (maize) straw silage (CSS), steam-exploded corn (maize) straw, steam-exploded wheat straw, and steam-exploded rice straw as fibre sources. A total of 224 male Greylag geese at 28 d of age were randomly assigned to one of the 4 experimental diets. 3. The birds fed on the CSS diets had higher average daily feed intakes than those fed on the steam-exploded straws. However, the 4 treatments had similar average daily gain, which contributed to significant differences in feed conversion ratios. The different fibre sources had no significant effects on the carcass characteristics. 4. The CSS-fed birds had larger gizzards and lower relative length of the caeca than the other three groups. However, the relative weights and lengths of the other gut segments, the relative weights of major organs and the pH values of the gastrointestinal contents were similar between the 4 treatments. It was concluded that straw fibres with different physico-chemical properties exerted an effect on daily feed intake and gastrointestinal development, especially for the gizzard. The pretreatment of straw had a large effect on utilisation efficiency and animal performance. Steam explosion is a promising straw pretreatment for inclusion in diets for geese.

Effects of dietary garlic scape meal on the growth and meat characteristics of geese.

This study evaluated the growth performance and meat characteristics of grower geese whose diets included garlic scape meal (GSM), a by-product of garlic production. Scape is the leaf-less flower stem of garlic. Garlic scape (GS) extracts contained 84.7 ± 3.8 µg/g dry weight (DW), 81.4 ± 8.2 µg/g DW, 0.78 ± 0.05 mg gallic acid equivalent/g DW and 31.67 ± 2.25 µg/g DW of allicin, alliin, total phenolics and flavonoid contents, respectively. In total, 120 White Roman geese aged 5 weeks were randomly distributed among 12 pens and fed on a grower diet ad libitum during the growth period. Employing a completely random design, 5 males and 5 females were placed in each pen. Each treatment was applied to three pens (in total 30 birds) and the treatments comprised the following: 1) control (maize-soybean meal), 2) 5% of maize replaced with 5% of GSM (5% GSM), 3) 10% of maize replaced with 10% of GSM (10% GSM) and 4) 15% of maize replaced with 15% of GSM (15% GSM). Each group of 30 birds was treated for 8 weeks. The results revealed that the 15% GSM group was characterised by a lower feed conversion ratio than the control group; however, these groups did not differ significantly in their body weights (BWs). In addition, the 10% GSM group did not differ in both the feed conversion ratio and consumption. The flavour intensity score of meats in the 10% GSM group was significantly lower than those of meats in the 5% GSM and control groups. The general acceptability scores of meats in the 5% GSM and control groups were higher than those of meat in the 10% GSM group. The study concluded that 5% dietary GSM in the feed did not adversely affect the growth performance, meat characteristics or sensory evaluation of grower geese. Hence, the environment can be protected by including agricultural waste in goose diets.

Effects of exploitation on an overabundant species: the lesser snow goose predicament.

Invasive and overabundant species are an increasing threat to biodiversity and ecosystem functioning world-wide. As such, large amounts of money are spent each year on attempts to control them. These efforts can, however, be thwarted if exploitation is compensated demographically or if populations simply become too numerous for management to elicit an effective and rapid functional response. We examined the influence of these mechanisms on cause-specific mortality in lesser snow geese using multistate capture-reencounter methods. The abundance and destructive foraging behaviours of snow geese have created a trophic cascade that reduces (sub-) Arctic plant, insect and avian biodiversity, bestowing them the status of 'overabundant'. Historically, juvenile snow geese suffered from density-related degradation of their saltmarsh brood-rearing habitat. This allowed harvest mortality to be partially compensated by non-harvest mortality (process correlation between mortality sources: ρ = -0.47; 90% BCI: -0.72 to -0.04). Snow goose family groups eventually responded to their own degradation of habitat by dispersing to non-degraded areas. This relaxed the pressure of density dependence on juvenile birds, but without this mechanism for compensation, harvest began to have an additive effect on overall mortality (ρ = 0.60; 90% BCI: -0.06 to 0.81). In adults, harvest had an additive effect on overall mortality throughout the 42-year study (ρ = 0.24; 90% BCI: -0.59 to 0.67). With the aim of controlling overabundant snow geese, the Conservation Order amendment to the International Migratory Bird Treaty was implemented in February of 1999 to allow for harvest regulations that had not been allowed since the early 1900s (e.g. a spring harvest season, high or unlimited bag limits and use of electronic calls and unplugged shotguns). Although harvest mortality momentarily increased following these actions, the increasing abundance of snow geese has since induced a state of satiation in harvest that has driven harvest rates below the long-term average. More aggressive actions will thus be needed to halt the growth and spread of the devastating trophic cascade that snow geese have triggered. Our approach to investigating the impacts of population control efforts on cause-specific mortality will help guide more effective management of invasive and overabundant species world-wide.