Behavioral and physiological responses of primiparous sows to mixing with older, unfamiliar sows.

Pigs are mixed into new social groups at various stages of production, and this study investigated the response of gilts to mixing with older unfamiliar sows. Four groups of 6 gilts and 1 group of 5 gilts were housed in stable groups until the most recently bred female reached d 39 of gestation. Then, stable groups were split such that 15 gilts remained in their home pens (CON) and 14 gilts were mixed (MIX) with 3 multiparous sows for 1 wk (M1), returned to the home pen for 1 wk, and then mixed with 3 different sows for 1 wk (M2). Continuous behavioral observations of gilt location in the pen, posture, aggressive, and other social interactions were made from the start of M1 and M2 for 5 h. Five-minute scans of location, posture, and behavior as well as salivary cortisol measurements were taken before, during, and after each mix week, whereas skin lesions were counted before and after each mix. During the mixed period, MIX gilts spent more (P ≤ 0.009) time in the individual feeding stalls, ventral lying, sitting, involved in aggression, and idle and less (P < 0.001) time in the straw-bedded area, lateral lying, and performing exploratory behavior (chewing, nosing, and rooting) than CON gilts. Additionally, MIX gilts had greater (P < 0.001) salivary cortisol concentrations and accumulated more (P < 0.001) skin lesions during mixing sessions compared to CON gilts. Mixed gilts in M2 spent more (P ≤ 0.013) time in the feeding stalls and ventral lying and less (P ≤ 0.029) time standing and in the dunging passageway compared to M1. Compared to M1, gilts had lower (P < 0.001) salivary cortisol concentrations and fewer (P ≤ 0.027) lesions in front and middle regions of the body during M2. During M2, salivary cortisol concentration was positively correlated with time spent in the dunging passageway (Spearman's rank correlation [rs] = 0.650, P = 0.022) and negatively correlated with time spent in the feeding stalls (rs = -0.762, P = 0.004). Results indicated that gilts adapted their behavior during M2 by using the feeding stalls more, and they became less active, especially when interacting with the sows. Despite this adaptation in M2, lesions and salivary cortisol in M IX gilts were much greater than in CON gilts, highlighting the severity of mixing gilts with multiparous sows.

Breeding system, colony and population structure in the weaver ant Oecophylla smaragdina.

Weaver ants (Oecophylla smaragdina) are dominant ants in open forests from India, Australia, China and Southeast Asia, whose leaf nests are held together with larval silk. The species, together with its sole congener O. longinoda, has been important in research on biological control, communication, territoriality and colony integration. Over most of the range, only one queen has been found per colony, but the occurrence of several queens per nest has been reported for the Australian Northern Territory. The number of males mating with each queen is little known. Here we report on the colony structure of O. smaragdina using published and new microsatellite markers. Worker genotype arrays reflect the occurrence of habitual polygyny (more than one queen per colony) in 18 colonies from Darwin, Northern Australia, with up to five queens inferred per colony. Monogyny (one queen per colony) with occasional polygyny was inferred for 14 colonies from Queensland, Australia, and 20 colonies from Java, Indonesia. Direct genotyping of the sperm carried by 77 Queensland queens and worker genotypic arrays of established colonies yielded similar results, indicating that less than half of the queens mate only once and some mate up to five times. Worker genotype arrays indicated that queens from Java and the Northern Territory also often mate with more than one male, but less often than those from Queensland. A strong isolation-by-distance effect was found for Queensland samples. The variation uncovered means that O. smaragdina is a more versatile study system than previously supposed.

Investigating the behavioural and physiological indicators of neonatal survival in pigs.

Survival is reduced in low birth weight piglets, which display poor thermoregulatory abilities and are slow to acquire colostrum. Our aim was to identify additional behavioural and physiological indicators of piglet survival incorporating traits reflective of both the intrauterine and extrauterine environment. Data were collected from 135 piglets from 10 Large White x Landrace sows to investigate which physiological measurements (e.g. individual placental traits), and which behavioural measurements (e.g. the quantification of piglet vigour), were the best indicators of piglet survival. Generalised linear models confirmed piglet birth weight as a critical survival factor. However, with respect to stillborn mortality, piglet shape and size, as measured by ponderal index (birth weight/(crown-rump length)(3)), body mass index (birth weight/(crown-rump length)(2)), respectively, and farrowing birth order were better indicators. With respect to live-born mortality, postnatal survival factors identified as crucial were birth weight, vigour independent of birth weight, and the latency to first suckle. These results highlight the importance of the intrauterine environment for postnatal physiological and behavioural adaptation and identify additional factors influencing piglet neonatal survival.

Bryophyte dispersal by flying foxes: a novel discovery.

This research provides the first evidence of dispersal of bryophytes and associated microorganisms through ingestion by a highly mobile vertebrate vector, the spectacled flying fox (Pteropus conspicillatus). Bryophyte fragments were found in faeces collected at four P. conspicillatus' camps in the Wet Tropics bioregion, northeastern Australia. These fragments were viable when grown in culture; live invertebrates and other organisms were also present. Our study has significantly increased understanding of the role of flying foxes as dispersal vectors in tropical forests.

Changes in milk composition during lactation in three species of insectivorous bats.

Changes in milk composition are described for three species of free-ranging insectivorous bats (Myotis lucifugus, M. velifer, and Tadarida brasiliensis) from early to mid (peak) lactation. Dry matter and energy concentrations in milk increased from early to mid-lactation. In M. lucifugus and T. brasiliensis, but not M. velifer, these increases were due largely to a rise in fat concentration, since protein and carbohydrate remained relatively constant. Energy content of milk (kJ.g-1) for each species from early through mid-lactation was related to dry matter (DM) as follows: M. lucifugus (y = 0.31 DM-0.32, r2 = 0.68), M. velifer (y = 0.48 DM-5.08, r2 = 0.99), and T. brasiliensis (y = 0.37 DM-1.51, r2 = 0.61). Comparison of the effect of sampling method on milk composition of T. brasiliensis indicated that fat, dry matter, and energy concentrations increased significantly from pre-dawn to pre-noon samples. Relatively high fat and low water levels in T. brasiliensis milk may reflect the limited access that lactating females have to free water, as well as need to minimize mass of stored milk during long foraging trips. Conversely, lower fat concentrations and higher water levels in milk in M. lucifugus and M. velifer may relate to the propensity for colonies of these two species to roost and forage near bodies of water. In addition, differences in milk fat concentrations observed among the three species may correlate to daily suckling schedules.(ABSTRACT TRUNCATED AT 250 WORDS)

Phylogenetic relations between microbats, megabats and primates (Mammalia: Chiroptera and Primates).

We examine the paraphylectic hypothesis of bat origins, both in the light of previous discussions, and in the light of new evidence from our analyses of neurological traits and wing morphology. Megabats share with primates a variety of complex details in the organization of neural pathways that have not been found in any other mammalian group, particularly not in microbats. The features previously used to link microbats and megabats have been examined and found to be questionable bases for support of a monophyletic origin. In particular, morphological analyses of the musculoskeletal adaptations associated with the flight apparatus are consistent with two separate origins of the mammalian wing. Taken together, these analyses suggest that megabats evolved from an early branch of the primate lineage. This branch was comprised of moderate-sized, phytophagous gliders, of which the other living descendants are the dermopterans. Microbats, in contrast, probably evolved much earlier from small, agile insectivores whose forelimbs had long metacarpals in relation to their phalanges.

The acrosome reaction in spermatozoa of the grey-headed flying fox (Pteropus poliocephalus: Chiroptera) exposes barbed subacrosomal material.

Acrosome reactions were induced in seminal spermatozoa of the megachiropteran Pteropus poliocephalus, the grey-headed flying fox, using the ionophore A23187 (10 microM in Tyrodes solution with 1% w/v BSA). Samples were taken at 0, 10, and 120 minutes and fixed for electron microscopy. Initial motility of approximately 70% decreased to approximately 10% over 2 hours. The first motile spermatozoa without acrosomal caps were seen after 6 minutes, and by 90 minutes approximately 60% of motile spermatozoa had completed the acrosome reaction. The first sign of the reaction (by TEM) appears to be swelling and cavitation of the acrosomal matrix within the apical and principal segments, followed or possibly accompanied by fusion and fenestration of the outer acrosomal and plasma membranes and dispersion of the matrix except from the equatorial segment. The end-product of the reaction thus conforms to that seen in other eutherian mammals. However, the reaction exposes a uniquely moulded organization of subacrosomal material ("pseudoperforatorium"), shaped like an anvil over the rostral rim of the flattened nucleus and encased by the remaining inner acrosomal membrane. This has two "lateral" spikes on each side that extend approximately to the same width as the head in the region of the equatorial segment. While these barbs could serve to stabilize or anchor the apical segment of the acrosome, their exposure following the acrosome reaction suggests some specific mechanical role in penetration of the zona pellucida or in protecting more caudal structures from abrasive damage.

An ultrastructural study of megachiropteran (Mammalia: Chiroptera) spermatozoa: implications for chiropteran phylogeny.

The fine structure of epididymal or electro-ejaculated spermatozoa of Pteropus poliocephalus, P. scapulatus, P. conspiculatus, P. alecto and Syconycteris australis is described. The sperm of all species were found to be very similar. The head is extremely flattened and spatulate; the nucleus is capped by a long acrosome that comprises the proximal half of the head and covers two-thirds of the nucleus area, and a prominent sub-acrosomal space possesses a unique 'anvil'-like shape. Redundant nuclear envelope forms a 'scroll' in a restricted region of the neck, next to the base of the proximal centriole and the most proximal of the mitochondria. The axoneme is atypical for mammals, the central singlets arising distal to the outer doublets. Coarse fibres 1, 5, 6 and 9 are larger than the remainder, a feature shared with the Microchiroptera, most insectivores and the Primates. The large sub-acrosomal space of the megachiropteran sperm is significantly is different from that of the Microchiroptera. We consider that the difference in sperm ultrastructure between the chiropteran sub-orders is not inconsistent with theories of a di-phyletic origin for this group. The use of sperm ultrastructure as a phylogenetic tool is discussed and comparisons with the spermatozoa of other closely related Eutheria are made.