Greater Body Condition Research Articles

Zebra Finch Females Avoided the Scent of Males with Greater Body Condition

The role of chemical communication in the social relationships of birds is receiving growing attention, but our knowledge is still scarce compared to that of other taxa. Previous evidence suggests that chemical cues emitted by birds may carry information about their characteristics, which may be useful in the context of sexual selection. However, experimental studies are needed to investigate the role of bird chemical cues in signalling the quality of potential partners. We performed an experimental study aimed at disentangling whether the female Zebra Finches (Taeniopygia guttata), use chemical cues to assess the body condition of potential partners. We offered focal females (N = 28) the scent of two males differing in body condition (body mass/tarsus length ratio) (N = 28 scent donor males). Our results showed that females can assess the body condition of potential partners using olfaction. However, contrary to what should be expected in a mate choice context, females avoided the scent of males with greater body condition. Our results, therefore, suggest that, despite performing the study during the breeding period, social interactions may be mediating the avoidance of the scent of the male in better condition in this gregarious species, probably to avoid a conspecific competitor with better body condition.

Influences of landscape composition on hunter‐harvested mallard body mass and condition in eastern Arkansas

AbstractWaterfowl with more body mass and a greater body condition during the non‐breeding season are thought to be more likely to survive and have increased productivity during the following breeding season. Body mass and body condition in waterfowl should reflect the resources available to them locally. We analyzed the relationship of landscape composition on mallard (Anas platyrhynchos) body mass and body condition (mass‐wing length index) among age and sex groups. We calculated these variables from hunter‐harvested mallards during the 2019–2020 and 2020–2021 duck hunting seasons in the Lower Mississippi Alluvial Valley of Arkansas, USA. We used linear mixed‐effects models to analyze changes in body mass and body condition with changes in the percent landscape composition of water cover, woody wetlands, herbaceous wetlands, rice, soybeans, and disturbance. We found that body mass and condition of harvested mallards were positively associated with greater proportions of water cover and woody wetlands but negatively associated with greater proportions of herbaceous wetlands and human disturbance from human infrastructure. Management actions focused on providing flooded and woody wetland areas on the landscape that allow waterfowl to access food resources, while decreasing the disturbance around wetlands in the form of road density and human infrastructure, should increase body mass and body condition in mallards spending the non‐breeding season in the Lower Mississippi Alluvial Valley.

Low impact of tuberculosis severity on wild boar body condition

Body condition (BC), is a measure to assess the health status of domestic and wild animals. When food resources are abundant, a decrease in BC may indicate an increase in the energetic expenditure due to the effects of growth, reproduction, or disease. BC impoverishment is one of the most common clinical effects of diseases progressing chronically, such as animal tuberculosis (TB) caused by bacteria belonging to the Mycobacterium tuberculosis complex. The Eurasian wild boar (Sus scrofa) is the main wild TB reservoir in the Mediterranean basin. The specific aims of this work were to assess the relationship between sex, age and TB severity altogether on the BC of wild boar. For this purpose, we used the kidney fat index (KFI), to assess the impact of TB progression on the BC of 1372 hunter-harvested free-ranging wild boar in seven populations in southern Spain. Surprisingly, TB had only slight effects on wild boar BC and individuals exhibiting severe TB showed greater BC than TB-free individuals. The age (adults had greater BC than juveniles) and sex (females had greater BC than males) were the main BC determinants in wild boar. Sampling population and season explained more BC variability than individual factors, suggesting that other external factors might play an important role in the BC, and probably on the impact of the disease on this wild reservoir. The low impact of TB on wild boar BC suggests that individuals with severe TB and good BC represent potential long-term super-shedders of this pathogen.

The better, the choosier: A meta-analysis on interindividual variation of male mate choice.

Male mate choice occurs in several animal species, but we know little about the factors that influence the expression of this behaviour. Males vary in their capacity to acquire mates (i.e. male quality), which could be crucial to male mate choice expression but it is often overlooked. Using a meta‐analytical approach, we explore interindividual variation in the expression of male mate choice by comparing the mating investment of males of different qualities and phenotypes to high‐ and low‐quality females. We used two datasets that together contained information from 60 empirical studies, comprising 52 species. We found that males of all qualities and phenotypes prefer high‐quality females, but differ in the strength of such preference. High‐ and medium‐quality males are choosier than low‐quality males. Similarly, males that are larger or in greater body condition are choosier than their counterparts. In contrast, male body mass and age are not associated with changes in male mate choice. We also show that experimental design may influence our understanding of male mating investment patterns, which may limit the generalisation of our findings. Nonetheless, we argue that male quality may be an important feature in the expression of male mate choice.

Researching 100 t cows: An innovative approach to identify intrinsic cows factors associated with a high lifetime milk production

Longevity is an important trait both from an economic and social perspective. Modern dairy cows are criticized for their short productive lifespan: only a minority of animals survives to a fourth lactation, implying that most cows are culled before reaching their maximal potential. In contrast, the population of 100 t cows (HT), reaching the threshold of 100,000 kg lifetime milk yield, is growing rapidly. As these cows combine a long lifespan with high functionality, a better understanding of their intrinsic characteristics might help us to improve the overall lifespan and lifetime production in dairy cows. The aim of the present research was to compare HT with their less-producing herd mates in order to identify intrinsic cow factors associated with longevity and high lifetime production. Therefore, we matched 26,248 HT with 691,597 herd mates, born in the same year in the same herd. Data were provided by Coöperatie rundveeverbetering (CRV) and contained birth dates, calving dates, milk yield and dam information. In addition, scores for conformation traits based on classifications in the first lactation and breeding values (for milk yield, fertility, udder health and claw health) were provided. Multivariable conditional logistic regression models were built to identify factors associated with reaching a lifetime milk yield of 100,000 kg. Results revealed cows born in September and born out of heifers to have the highest odds to become a HT. When cows received a score ≥ 83 (population average 80) for udder and feet & legs conformation, they had higher odds of reaching the 100,000 kg threshold. While a greater body condition and larger rump angle increased the odds of becoming a HT, this was decreased in cows with a large body depth. Finally, breeding values for milk yield, fertility, udder health and claw health were positively associated with the likelihood of reaching a lifetime milk yield of 100,000 kg. In conclusion, to increase lifetime milk yield in dairy herds, farmers should select heifers with high scores for conformation traits like udder and feet & legs and high breeding values for milk yield, fertility and udder health. Furthermore, our data suggest that being born in September out of a heifer potentially contributes to reaching a high lifetime milk yield.

Communal egg‐laying behaviour and the consequences of egg aggregation in the brown anole (Anolis sagrei)

AbstractCommunal nesting is a behaviour that involves multiple females laying eggs in the same nest or nesting site. This behaviour may be a consequence of a shortage of preferable nest sites (constraint hypothesis) or an adaptation generated by fitness benefits associated with egg aggregation (adaptive hypothesis). Experimental tests of these hypotheses require information about maternal nest site choice and its fitness consequences. To address these, we studied a lizard (brown anole; Anolis sagrei) that produces single‐egg clutches, but often aggregates eggs in nest sites. In a lab study, females were given the option of nesting in (a) soil previously used as nest substrate vs. fresh soil and (b) soil with eggshells vs. without eggshells. We also experimentally examined the effects of egg aggregation by incubating eggs singly, in groups of four, and in groups of nine. We recorded egg surface temperature, water uptake, and hatchling morphology. Females were more likely to nest in pots with used soil and with eggshells than in pots with fresh soil or without eggshells. We observed no effects of egg aggregation on egg survival, egg temperature, or most measures of hatchling morphology. However, singly‐incubated eggs absorbed more water than eggs incubated in the four and nine egg aggregations and this resulted in offspring with greater body condition (i.e. heavier for their length) at hatching. The behavioural experiment demonstrates that females actively choose nest sites that have been used previously (as expected under the adaptive hypothesis), but the egg‐aggregation experiment shows no benefits to offspring based on the variables measured. Thus, results of the behaviour study support the adaptive hypothesis; however, results from our egg‐incubation study do not. Likely, the adaptive and constraint hypotheses are not mutually exclusive, and a diversity of factors influence the evolution of communal nesting behaviour.

Addition of Tannin in Lamb Diets after Weaning: Impact on Performance and Hematological and Biochemical Variables

Background: In ruminants, the weaning period is a critical phase, because these young animals are allocated to various facilities and receive different feeds. Alternatively, supplements and additives can be used. The tannins are polyphenols produced by plants; constitute a group of complex secondary metabolic factors that inhibit the consumption by herbivores or the development of microbial agents. The objective of this study was to determine whether the addition of condensed tannin extract from quebracho trees (Schinopsis lorentzii) in lamb diets after weaning would have beneficial effects on growth and health.Materials, Methods & Results: Forty lambs were assigned randomly to 1 of 4 treatments (10 lambs/treatment): T1 (0%; control), T2, T3, and T4 was 0.3, 0.6 and 0.9 % of quebracho extract in the diet, respectively. The T2 (0.3%) lambs had greater body condition scores (P = 0.005), and although they did not differ significantly, they had numerically greater body weight (P = 0.067) and weight gain (P = 0.072), than the control lambs. The anthelmintic and anticoccidial effect was not possible to verify because no animals in any group were naturally infected by helminths or coccidia. The T4 lambs had greater numbers of erythrocytes (days 10 and 40) [P < 0.05], greater hemoglobin concentrations (days 10 and 40), and greater numbers of total leukocytes (day 10) as a result of greater numbers of neutrophil at the end of the adaptation period (day 10) compared to T1. The T3 and T4 lambs had greater (P < 0.05) serum total protein (days 10 and 40) because of greater concentration of serum globulins (days 10 and 40) compared to T1, suggesting that the addition of tannin stimulated the immune system. The addition of quebracho in the diet affected serum concentrations of glucose, triglycerides, and cholesterol at some times and treatments (P < 0.05). However, these changes did not follow a pattern; this finding only suggested that there was an influence on the metabolism of carbohydrates and lipids. The T2 lambs showed no differences on hemogram or serum clinic biochemistries (P > 0.05); however, they had a greater body condition scores than T1 (P < 0.05).Discussion: According to literature, if condensed tannins are supplied in moderate quantities (≤ 5% of diet) to ruminants, they can prevent bloating, increase the supply of undegraded protein in the rumen and improve the use of essential amino acids. It is also known that tannins in diet may increase urea recycling efficiency by increasing the concentration of urea in saliva and salivary flow into the rumen. Studies observed that cattle and sheep given feed containing condensed tannins had higher production of wool, meat, milk, and ovulation rates in females, desirable effects on animal production. According to the literature, dietary supplementation with tannins from chestnut and quebracho (2 g/kg of feed) to Holstein cattle changed the composition of the ruminal microbiota, particularly the bacteria that degrade fiber and starch, reducing the abundance of Prevotella and Fibrobacter, favoring Ruminococcaceae and other members of the phylum Firmicutes, increasing the pH and decreasing urease activity in ruminal fluid. Therefore, when tannins are supplemented at low concentrations, they can stimulate the intake and utilization of essential amino acids in the small intestine, increasing performance and exerting an anthelmintic effect. Our study found that the addition of 0.3% of quebracho in the diet improved lamb growth and health after weaning. It is therefore an additive that can be used to feed lambs in critical post weaning period.

The potential interaction between ewe body condition score and nutrition during very late pregnancy and lactation on the performance of twin-bearing ewes and their lambs.

ObjectiveThe present study aimed to determine the impact of ewe body condition score (BCS) (over a range of 2.0 to 3.0) and nutritional treatments (consisting of differing herbage masses) during very late pregnancy and lactation and their potential interaction on the performance of twin-bearing ewes and their lambs to weaning.MethodsOn day 142 of pregnancy, twin-bearing ewes with a BCS of 2.0, 2.5, or 3.0 were allocated to a “Moderate’ or ‘Unrestricted’ nutritional treatment until day 95 of lactation (weaning). The nutritional treatments aimed to achieve average herbage masses of 1,200 to 1,300 kg dry matter (DM)/ha (Moderate) and 1,500 to 1,800 kg DM/ha (Unrestricted).ResultsThere were no three-way interactions between ewe BCS group, nutritional treatment and time for any ewe or lamb parameter. The nutritional treatments had no effect (p>0.05) on lamb birth or weaning weight. Lambs born to Moderate ewes had greater survival and total litter weight at weaning (p<0.05). Regardless of BCS group, Unrestricted treatment ewes had greater body condition and back-fat depth at weaning than Moderate treatment ewes (p<0.05). Ewes of BCS 2.0 group reared lighter lambs to weaning (p<0.05) and tended to have a lower total litter weight (p = 0.06) than BCS 3.0 group ewes.ConclusionThis study suggests farmers should aim to have all ewes with a BCS of 2.5 or 3 in late pregnancy for optimal lamb weaning performance. Furthermore, there is no benefit to lamb production of offering ewes pasture masses >1,200 kg DM/ha during very late pregnancy and lactation.

Effect of oestradiol benzoate on oestrus intensity and pregnancy rate in CIDR treated anoestrus nulliparous and multiparous buffalo

The objective of the present study was to examine if administration of oestradiol benzoate (OEB) after removal of control internal drug releasing device (CIDR) could enhance oestrous intensity and pregnancy rate in anovular nulliparous and multiparous Nili-Ravi buffalo. For this, a total of 298 nulliparous (n=91) and multiparous (n=207) buffaloes received a CIDR on Day 0, and were administered PGF2α on Day 6 followed by removal of CIDR on Day 7. At Day 8, OEB was administered in approximately half of nulliparous (n=45/91) and multiparous (n=100/207) buffalo. All animals were fixed time inseminated 48 and 60h after CIDR removal, respectively. The results showed that administration of OEB but not the parity, improved oestrous intensity (3.15±0.05 vs 2.99±0.05; P=0.0026) compared to those not received OEB, respectively. However, OEB did not affect (46.2 vs 44.1; P=0.8) pregnancy per AI (P/AI). In addition, P/AI was greater (50.7 vs 39.6; P=0.036) in multiparous compared to nulliparous buffalo, respectively. The oestrous intensity (P=0.025) and response to OEB (P=0.0002) was greater in buffalo having a greater body condition (>3.0). Though, non significant, timing of ovulation was more synchronous (62.9±1.8 vs 72.4±3.6h; P>0.05) and ovulation rate was greater (91% vs 64%; P>0.05) in buffalo after OEB administration. It is concluded that administration of OEB in conjunction with the CIDR improves oestrous intensity without affecting P/AI in nulliparous and multiparous anovular buffalo.

Host, pathogen, and environmental characteristics predict white-nose syndrome mortality in captive little brown myotis (Myotis lucifugus).

An estimated 5.7 million or more bats died in North America between 2006 and 2012 due to infection with the fungus Pseudogymnoascus destructans (Pd) that causes white-nose syndrome (WNS) during hibernation. The behavioral and physiological changes associated with hibernation leave bats vulnerable to WNS, but the persistence of bats within the contaminated regions of North America suggests that survival might vary predictably among individuals or in relation to environmental conditions. To investigate variables influencing WNS mortality, we conducted a captive study of 147 little brown myotis (Myotis lucifugus) inoculated with 0, 500, 5 000, 50 000, or 500 000 Pd conidia and hibernated for five months at either 4 or 10°C. We found that female bats were significantly more likely to survive hibernation, as were bats hibernated at 4°C, and bats with greater body condition at the start of hibernation. Although all bats inoculated with Pd exhibited shorter torpor bouts compared to controls, a characteristic of WNS, only bats inoculated with 500 conidia had significantly lower survival odds compared to controls. These data show that host and environmental characteristics are significant predictors of WNS mortality, and that exposure to up to 500 conidia is sufficient to cause a fatal infection. These results also illustrate a need to quantify dynamics of Pd exposure in free-ranging bats, as dynamics of WNS produced in captive studies inoculating bats with several hundred thousand conidia may differ from those in the wild.

Individual quality persists between years: individuals retain body condition from one winter to the next in Teal

Few studies have considered how body condition changes over time in individual birds, and most of these concerned long-lived breeding birds. We used a large database of Common Teal Anas crecca ringed and recaptured while wintering in the Camargue to study inter-annual persistence in wing length and body condition. Winter body condition may be a major determinant of survival during that season, and may further be related to breeding success. Indices of condition were compared for individual Teal between the moments of ringing and of recapture the following winter, analyzing each sex and age class (adult or juvenile) separately. Wing length was highly repeatable between years, though some limited annual variation was also recorded in adult males. Using scaled mass index as an index of body condition, we observed that condition at ringing was the strongest predictor of body condition at recapture for males and juvenile females, although inter- and intra-annual variation was also significant in most cases. The value of the slope for the relationship between individual body condition indices at ringing and recapture did not differ from 1 for males and for adults, whereas, for juvenile females, the slope was significantly greater than 1, indicating that individual differences in condition became more exaggerated over time. When analyses were repeated using crude body mass instead of a condition index, results were generally similar. Birds recaptured the following winter had a greater body condition at ringing that those that were not recaptured, supporting the hypothesis of a link between winter body condition and return probability. Our results demonstrate the importance of a head start in Teal, given persistent effects of obtaining better condition in the first winter, and suggest specific age and sex effects. They also underline the value of condition indices as a long-term predictor of individual quality in birds, even during the non-breeding season and for such a relatively short-lived species.

Early weaning in Northern Great Plains beef cattle production systems: I. Performance and reproductive response in range beef cows

A study was conducted to determine if early weaning spring born calves can be an alternative management strategy during drought and if early weaning facilitates rebreeding of young cows. Our objectives were to determine effects of early weaning at the start of breeding on cow body weight, body condition score, and reproductive performance with or without estrous synchronization and AI in two herds in the Northern Great Plains, USA. In Exp. 1 and 2, crossbred cows were stratified within cow age by postpartum interval, and calf sex, and were assigned within strata to one of two weaning treatments at the start of breeding when calves averaged 80-d of age: (1) early weaned (permanent calf removal); or (2) no weaning (calves suckled cows until normal weaning approximately 210-d of age). Cows in Exp. 1 were exposed to natural service whereas cows in Exp. 2 were exposed to estrous synchronization for AI using a CIDR for 7d with GnRH at CIDR insertion and PGF2α at CIDR removal followed by natural service. In Exp. 3, cows were stratified within breed by age, postpartum interval, calf sex, and AI sire and were assigned within strata to one of two weaning treatments at the start of breeding, as described for Exp. 1 and 2. Estrous cycles of all cows were synchronized for AI using one of two protocols including 14d CIDR+PGF2α 16d following CIDR removal (primiparous cows) or a CIDR insert for 7d with GnRH at CIDR insertion and PGF2α at CIDR removal (multiparous cows). Cows in Exp. 2 and 3 were bred by AI approximately 12h after observation of estrus or by timed AI at 80h after PGF2α concurrent administration of GnRH. Artificial insemination (Exp. 2), breeding season pregnancy rate, and day of conception was not influenced (P>0.10) by weaning treatment for Exp. 1 and 2. However, early weaned cows in Exp. 3 had 12.0% greater (P=0.03) AI pregnancy rates and conception occurred 3.78d earlier (P=0.03) than normal weaned cows. At the time of normal weaning, cows that had their calves removed at early weaning were heavier and had greater body condition (P<0.01) than normal weaned cows in each experiment. We conclude that early-weaning beef cows at the start of the breeding season improved BW gain and BCS allowing those females to enter winter in greater BCS then NW cows, but improvements in reproductive performance were inconsistent.

Do Juvenile White Perch Morone americana Grow Better in Freshwater Habitats of the Blackwater River Drainage (Chesapeake Bay, MD, USA)?

Increasing rates of freshwater habitat loss in the Chesapeake Bay (and elsewhere) have renewed interest in the role of freshwater in population integrity for euryhaline fishes. Freshwater habitats may be important nurseries for juveniles of anadromous species. Using length–weight residuals and scales, we determined if body condition and growth of juvenile (<120 mm total length) white perch Morone americana (a semi-anadromous species) differed between brackish and freshwater tributaries within the Blackwater River drainage (Chesapeake Bay Watershed, U.S.A.). We then examined how monthly variation in body condition varied with monthly variation in selected environmental factors. Body condition differed between tributaries and was greater in freshwater (specific conductivity <0.45 mS) than brackish water when water temperature was greater than 9.6°C. White perch growth rates did not differ between tributaries, except for a short time during summer or early fall. Some anadromous fishes may spawn in freshwater to promote greater body condition, thereby ensuring a quality contingent of individuals for the population. With continued loss or impairment of freshwater habitat, the availability of nurseries for juvenile white perch will be reduced and reduce the number of quality juveniles recruiting to the adult population.

Fecundity compensation in the three-spined stickleback Gasterosteus aculeatus infected by the diphyllobothriidean cestode Schistocephalus solidus

Causal explanations for host reproductive phenotypes influenced by parasitism fit into three broad evolutionary models: (1) non-adaptive side effect; (2) adaptive parasitic manipulation; and (3) adaptive host defence. This study demonstrates fecundity compensation, an adaptive non-immunological host defence, in the three-spined stickleback fish (Gasterosteus aculeatus) infected by the diphyllobothriidean cestode Schistocephalus solidus. Both infected and uninfected female sticklebacks produced egg clutches at the same age and size. The reproductive capacity of infected females decreased rapidly with increased parasite : host body mass ratio. Body condition was lower in infected females than uninfected females and decreased with increasing parasite : host mass ratio. Females with clutches had greater body condition than those without clutches. A point biserial correlation showed that there was a body condition threshold necessary for clutch production to occur. Host females apparently had the capacity to produce egg clutches until the prolonged effects of nutrient theft by the parasite and the drain on resources from reproduction precluded clutch formation. Clutch mass, adjusted for female body mass, did not differ significantly between infected and uninfected females. Infected females apparently maintained the same level of reproductive allotment (egg mass as proportion of body mass) as uninfected females. Infected females produced larger clutches of smaller eggs than uninfected females, revealing a trade-off between egg mass and egg number, consistent with the fecundity compensation hypothesis. The rapid loss of reproductive capacity with severity of infection probably reflects the influence of the parasite combined with a trade-off between current and future reproduction in the host. Inter-annual differences in reproductive performance may have reflected ecological influences on host pathology and/or intra-annual seasonal changes. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 807‐819.

Demographic and Phenotypic Effects of Human Mediated Trophic Subsidy on a Large Australian Lizard (Varanus varius): Meal Ticket or Last Supper?

Humans are increasingly subsidizing and altering natural food webs via changes to nutrient cycling and productivity. Where human trophic subsidies are concentrated and persistent within natural environments, their consumption could have complex consequences for wild animals through altering habitat preferences, phenotypes and fitness attributes that influence population dynamics. Human trophic subsidies conceptually create both costs and benefits for animals that receive increased calorific and altered nutritional inputs. Here, we evaluated the effects of a common terrestrial human trophic subsidies, human food refuse, on population and phenotypic (comprising morphological and physiological health indices) parameters of a large predatory lizard (∼2 m length), the lace monitor (Varanus varius), in southern Australia by comparison with individuals not receiving human trophic subsidies. At human trophic subsidies sites, lizards were significantly more abundant and their sex ratio highly male biased compared to control sites in natural forest. Human trophic subsidies recipient lizards were significantly longer, heavier and in much greater body condition. Blood parasites were significantly lower in human trophic subsidies lizards. Collectively, our results imply that human trophic subsidized sites were especially attractive to adult male lace monitors and had large phenotypic effects. However, we cannot rule out that the male-biased aggregations of large monitors at human trophic subsidized sites could lead to reductions in reproductive fitness, through mate competition and offspring survival, and through greater exposure of eggs and juveniles to predation. These possibilities could have negative population consequences. Aggregations of these large predators may also have flow on effects to surrounding food web dynamics through elevated predation levels. Given that flux of energy and nutrients into food webs is central to the regulation of populations and their communities, we advocate further studies of human trophic subsidies be undertaken to evaluate the potentially large ecological implications of this significant human environmental alteration.

Reproductive ecology of wild tammar wallabies in natural and developed habitats on Garden Island, Western Australia

Reproduction may be influenced by major environmental changes experienced by an entire population as well as variation within a population in maternal resource availability or quality. We examined relationships between body condition and reproductive traits in two wild populations of the seasonally breeding tammar wallaby (Macropus eugenii) on Garden Island, Western Australia, that differed in access to supplemental food resources. Body condition changed predictably over the year, with females losing condition over the dry summer and gaining condition over the winters, when lactation occurs and most annual precipitation falls. Body condition influenced reproduction, with females of greater body condition more likely to have a pouch young, and to have a larger pouch young, early in the reproductive season. This intrapopulation pattern was opposite to that seen across populations – females in a native bushland were in poorer condition yet were more likely to have pouch young, and had larger pouch young, in March than did females living in a water-supplemented habitat on a naval base. Body condition did not influence the probability of weaning a pouch young in a year, nor did reproductive success influence changes in body condition across seasons. Instead, annual variation in precipitation had a dramatic effect on population weaning success in the native bushland, but not on the naval base. In summary, individual variation in body condition as well as large climatic variation influenced the reproduction of tammar wallabies on Garden Island, but the nature of the effect depended on the different habitats experienced by the two study populations.

Body condition is associated with a shorter breeding season and reduced ovulation rate in subtropical goats

To determine the effect of body condition on the characteristics of the breeding season in female goats from subtropical Mexico, does in either greater- or lesser-body condition ( n = 20/group) were monitored for the expression of estrous behavior, ovulation and ovulation rate between June and April. The commencement of estrus and ovulation occurred earlier ( P < 0.05) in does in greater than lesser body condition. The cessation of estrus and ovulation was later ( P < 0.05) in female goats with greater than those with lesser body condition. Does in greater body condition had more ( P < 0.001) normal estrous cycles than those in lesser body condition. As consequence, does from the greater body condition group had fewer short ( P < 0.001) or long ( P < 0.05) estrous cycles than those of in the lesser body condition group. The ovulation rate was greater ( P < 0.01) in the greater (1.9 ± 0.1) than lesser body condition does (1.6 ± 0.1). In conclusion, female goats in lesser body condition have a shorter breeding season, more abnormal estrous cycles, and fewer ovulations than does in greater body condition.

408. Liver gene expression in suckled postpartum beef cows maintained on moderate and improved subtropical pasture

The liver is the first organ to receive absorbed nutrients from the splanchnic vasculature1 which places the liver at an important juncture between nutrition, metabolic homeostasis and reproductive function. The best described component of this interface is secretion of IGF-1 by the liver and dependence of ovarian follicular maturation on hepatic-derived IGF-12. The aim in the present study was to ascertain the expression of hepatic genes associated with metabolic regulation in postpartum beef cows maintained on moderate or improved pasture, and with contrasting liveweight and body condition. Multiparous Droughtmaster cows (Bos taurus × Bos indicus) were placed on moderate (MP, n = 7) or improved (IP, n = 7) pasture at 6–7 months of gestation and remained on the treatments after calving. Liver biopsies were taken 6 weeks after calving and gene expression was determined by quantitative PCR using SYBR Green3. Week 6 represents attainment of the plateau in nutrient demand for lactation. Data were analysed by ANOVA using SAS STAT. One week after calving, IP cows had greater (P &lt; 0.01) liveweight and body condition score (BCS) than MP cows (585 ± 12 kg and 528 ± 21 kg; 3.7 ± 0.2 BCS and 2.3 ± 0.2 BCS). IP cows had greater (P &lt; 0.05) relative expression of hepatic genes associated with cholesterol biosynthesis (sterol regulatory element binding factor, SREBF2; peroxisome proliferators-activated receptor delta, PPARD), fatty acid biosynthesis (carnitine palmitoyl-transferase, CPT1A; acyl-CoA oxidase, ACOX1; fatty acid desaturase 1, FADS1; sterol regulatory element binding factor 1, SREBF1) and insulin signalling (hepatic insulin receptor substrate 1, IRS1). IP cows resumed cyclic ovarian function between 11–16 weeks postpartum and one MP cow had cycled by 16 weeks. The differences in expression of metabolic genes between MP and IP cows may have partly contributed to differences in reproductive function postpartum. (1) Drackley J et al. 2006 Journal of Dairy Science 89:1324–36 (2) Lucy MC 2000 Journal of Dairy Science 83:1635–47 (3) Loor JJ et al. 2006 Physiological Genomics 27:29–41

Effects of seasonality and migratory prey on body condition of Cichla species in a tropical floodplain river

Abstract – In this study we examine trends in body condition of three Cichla species native to the Cinaruco River, Venezuela. Specifically, we characterise the potential subsidy provided by migratory Semaprochilodus kneri to Cichla by comparing condition among species, hydrologic seasons and different size‐classes (based on the ability to consume S. kneri assuming gape‐limitation). All three species had lowest body condition during the rising‐water season (following the reproduction period). Only Cichla temensis had greater body condition during the falling‐water season than low‐water season. During the falling‐water season, C. temensis &gt;300 mm SL had significantly greater condition than smaller conspecifics. Annual migration of S. kneri into the river during the falling‐water season provides a resource subsidy to large C. temensis. Transfer of whitewater production into nutrient‐poor rivers by migratory fishes appears to be a general phenomenon in the major Neotropical river basins and may partially account for high standing stocks of large piscivores in these unproductive ecosystems.

Suplementação com diferentes níveis de silagem de milho para vacas de descarte de diferentes grupos genéticos submetidas ao pastejo

O trabalho foi realizado objetivando-se avaliar o efeito da suplementação com silagem de milho sobre o desempenho de vacas de descarte em terminação, em pastagem de aveia preta (Avena strigosa) e azevém (Lolium multiflorum). A silagem de milho utilizada foi do híbrido AG-5011, contendo 6,59% de Proteína Bruta. Foram utilizadas 30 vacas de descarte dos grupos genéticos ¾ Charolês (C) ¼ Nelore (N) ou ¾ N ¼ C com média de idade de 5 anos, recebendo ou não oferta de 1,25% do peso vivo (PV) de silagem de milho (matéria seca) ou oferta à vontade da mesma silagem. Não houve interação entre grupo genético e oferta de suplemento. Animais que receberam silagem à vontade apresentaram maior consumo absoluto de suplemento (4,57 contra 4,34kg), desaparecendo esta diferença quando o consumo foi expresso em percentagem do peso vivo (1,07 contra 0,99%). As vacas que receberam suplemento apresentaram maior ganho de peso médio diário (GMD) em comparação às que não receberam (0,879kg), independente do nível de oferta. A oferta de silagem à vontade não proporcionou maior GMD (1,175kg) em relação aos que receberam 1,25% do PV (1,214kg). O maior consumo de silagem proporcionou maior escore corporal final (3,42 pontos), sendo que as vacas que receberam 1,25% do PV (3,26 pontos), não diferiram daquelas que não receberam suplemento (3,19 pontos). As vacas ¾ C ¼ N apresentaram maior consumo absoluto de suplemento (3,05 contra 2,89kg), maior GMD (1,196 contra 0,983kg/animal/dia) e maior escore corporal ao final do experimento (3,37 contra 3,21 pontos).