Assessing the potential for Grey Squirrels Sciurus carolinensis to compete with birds at supplementary feeding stations

Supplementary feeding of birds, particularly in urban areas, is often associated with increased population size and fecundity. In the UK, the non‐native Grey Squirrel Sciurus carolinensis is common in rural and urban habitats. It exploits supplementary feeders and may induce interference competition by excluding birds, but empirical evidence of this is unavailable. Using controlled model presentation experiments, we demonstrate that Grey Squirrels could reduce bird use of supplementary feeders and induce interference competition. Total bird resource use was reduced by 98% and most species exhibited similar sensitivities. The likelihood and magnitude of interference competition will depend on how rapidly displaced birds find alternative food sources; it will be greatest where there are high Grey Squirrel densities and few supplementary feeders. Other studies suggest that supplementary feeding increases Grey Squirrel numbers, and the species is also predicted to expand its non‐native range across most of Europe. Our data indicate that Grey Squirrels may eventually alter the net effect of supplementary feeding on bird populations across the European continent; increased use of squirrel‐proof feeders may help to minimize such effects.     

Lower foraging efficiency of offspring constrains use of optimal habitat in birds with extended parental care

After reproducing successfully, birds with extended parental care form family groups. Despite being the dominant social unit, such family groups have been reported to switch to alternative habitat earlier than adults without offspring, with potential negative carry‐over effects for the next breeding season. Here we test a proposed mechanism for this earlier habitat switch, namely a low foraging efficiency in juveniles. Such a test is best performed under controlled conditions because in the field families may occupy food patches of a different quality than singles or pairs without young. We studied this mechanism in Bewick's Swans Cygnus columbianus bewickii, which trample (or ‘treadle’) for food buried in the sediment. The gross intake rate of juveniles was as low as 60% of that of adults, depending on the burial depth of the food. Trampling effort did not differ between age classes, but differences in intake rate were related to body size, suggesting that larger or heavier birds were trampling more efficiently. Corresponding giving‐up densities in the field were calculated to be c. 60% higher for juveniles than for adults. Our findings are consistent with the hypothesis that the lower foraging efficiency of juveniles may be responsible for the segregation of family groups from adults without offspring.     

Deuterium oxide dilution accurately predicts water intake in sheep and goats

The aim of this study was to test whether the deuterium oxide dilution technique accurately predicts water intake in sheep and goats. Two other issues were also studied: (i) a comparison of water intake in sheep and goats and (ii) an assessment of whether observations of drinking behaviour can accurately measure the water intake. In this study, eight dry Boer goats and eight dry German Black Head Mutton ewes were kept under controlled stable conditions. Animals had access to hay and water ad libitum. Diurnal drinking behaviour was recorded by video. Individual daily water intake was measured and estimated for 2 weeks by re-weighing water buckets and from water kinetics using the deuterium oxide dilution technique, respectively. In addition, dry matter intakes were directly measured and were significantly higher in sheep than in goats. The average daily water consumption by drinking differed significantly between the two species, with higher intakes in sheep than in goats. Total body water expressed as a percentage of body mass did not differ between species. Measurement methods of total water intake (TWI) using deuterium oxide dilution and re-weighing water buckets did not differ significantly in both species (P = 0.926). Results obtained for measured and estimated TWI confirm that the isotope dilution technique gives reliable results for estimates of water intake in sheep and goats. The higher amount of water intake in sheep was also reflected by their drinking behaviour. Sheep spent approximately 0.3% per 24-h drinking, while Boer goats spent only 0.1%. However, measured and estimated TWIs were only moderately correlated to the daily time spent drinking. The lower water intake found in Boer goats confirms a superior water management capacity compared with Black Head Mutton sheep even under temperate conditions.     

Feeding behaviour of sheep fed lucerne v. grass hays with controlled post-ingestive consequences

Understanding what determines feeding behaviour in herbivores is essential to optimise the use of forages in breeding systems. Herbivores can evaluate foods by associative learning of their pre-ingestive characteristics (taste, odour, etc.) and their post-ingestive consequences. Post-ingestive consequences are acknowledged as influencing intake and food choices, but the role of pre-ingestive characteristics is still being debated. Our experiment was designed to test their separate effects on daily dry matter intake (DMI), intake patterns and short-term choices in sheep by crossing the nature of the hay orally consumed (o) ad libitum, lucerne (L) or grass (G), with the nature of the hay introduced into the rumen (r), L or G, at a rate of half the total amount of hay received the day before. We applied four treatments, Go/Gr, Go/Lr, Lo/Gr and Lo/Lr, to test the effects of (i) post-ingestive consequences with similar pre-ingestive characteristics (Go/Gr v. Go/Lr; Lo/Gr v. Lo/Lr) and (ii) pre-ingestive characteristics with similar post-ingestive consequences at the end of the feeding period (Go/Lr v. Lo/Gr). Six rumen-fistulated sheep underwent all the treatments over 11-day periods in a latin square design. Eating time was restricted to 6 h/day, intraruminal introductions were performed just before food offer and choice tests were conducted after food removal. For similar pre-ingestive characteristics, DMI increased when L hay was introduced into the rumen rather than G (P < 0.05), possibly owing to a lower fill effect of L due to its lower NDF content and higher rumen degradability. The increased DMI resulted from longer eating time when G was orally consumed (149 v. 192 min, P < 0.05), whereas it resulted from higher intake rate with L (4.8 v. 6.1 g/min, P < 0.05). For similar post-ingestive consequences at the end of the feeding period (Go/Lr and Lo/Gr), DMI were similar (P > 0.05). Pre-ingestive characteristics or palatability per se did not therefore influence daily intake, although they influenced eating patterns. Pre-ingestive characteristics also greatly influenced short-term choices in favour of the hay that was not previously consumed, independently of any post-ingestive influence. This study confirms the effects of post-ingestive consequences on daily intake, but demonstrates that these variations are obtained by different behavioural adjustments under the influence of pre-ingestive characteristics. Preference for novelty, regardless of post-ingestive consequences, thus suggests that sheep may seek a diverse diet more for pleasure than for functional purposes, with implications for animal welfare.     

Influence of Summer and Autumn Nutrition on Body Condition and Reproduction in Lactating Mule Deer

ABSTRACT Recent work suggests that availability and quality of forage in late summer and early autumn, a time when female ungulates face multiple energetic demands, is critical to reproduction in wild ungulates. Therefore, we examined direct links between nutritional quality of diets, body condition, and reproduction of lactating mule deer. Using captive mule deer, we tested the hypothesis that females consuming diets with lower digestible energy (DE; kJ/g) would have lower DE intake rates (DEI; MJ/day), have less body fat and muscle, have later estrus cycles, and have lower pregnancy and twinning rates. Deer fed lower DE diets had lower DEI during summer and autumn. In turn, deer with lower DEI, regardless of diet DE, had lower body mass, body fat, and muscle thickness. When nutritional quality of diets began to decline earlier in the summer, relationships between food quality, DEI, and body condition were stronger. Although DEI did not influence estrus date for deer that became pregnant before 21 December, deer with lower DEI had a lower probability of becoming pregnant and had a lower probability of producing twins. Measures of body condition in October (i.e., body mass, body fat, and muscle depth) predicted pregnancy and twinning rates in mule deer. Serum concentration of hormones leptin and Insulin Growth Factor 1 were not good predictors of body condition or reproduction. These findings suggest that managers concerned with productivity of mule deer populations should consider focusing on assessing and improving quality of forage available in summer and autumn.     

Cholecystokinin and bombesin act independently to decrease food intake in the rat

The satiating effects of cholecystokinin-octapeptide (CCK-8) and bombesin (BBS) when injected alone and in combination were compared in intact rats. When injected alone, both CCK-8 and BBS elicited a dose-related decrease of 30-minute food intake. Injections of BBS were less potent than the equivalent doses of CCK-8 in producing satiety. BBS reached an asymptotic level of suppression of approximately 40 percent at a dose of 2 micrograms/kg, whereas injections of 4 micrograms/kg of CCK-8 resulted in a 72 percent suppression of food intake. When the two peptides were administered in a single injection, the resulting suppression of food intake was equivalent to that which would be predicted if their effects were completely additive. These results support the hypothesis that CCK-8 and BBS act via independent mechanisms to induce satiety. A preliminary model of peptidergic satiety, based on this hypothesis, is proposed.     

自拟益气通阳活血方治疗阿尔茨海默病的临床研究

摘要 目的：分析自拟益气通阳活血方治疗阿尔茨海默病的临床效果。方法：选取2020年10月~2022年4月于中国人民解放军空军军医大学第一附属医院接受治疗的阿尔茨海默病患者104例，依据入院先后顺序编号，按单双号分为对照组（n=52）和研究组（n=52）。对照组进行常规西药治疗，研究组在此基础上进行自拟益气通阳活血方治疗。比较两组临床疗效、治疗前后中医证候积分、日常生活活动能力、认知功能、血清去甲肾上腺素（NE）、多巴胺（DA）、乙酰胆碱转移酶（ChAT）水平、β淀粉样蛋白前体（APP）、β淀粉样蛋白1-42（Aβ1-42）、丙二醛（MDA)、超氧化物歧化酶（SOD）水平，并比较两组安全性。结果：治疗后，两组中医证候积分均降低，且研究组显著低于对照组（P<0.05）；研究组总有效率为94.23%，明显高于对照组的78.85%（P<0.05）；治疗后，两组简易智能精神状态检查量表（MMSE）评分与蒙特利尔认知评估量表（MoCA）评分研究组均高于对照组（P<0.05）；治疗后，两组barthel指数评分及日常生活能力量表（ADL）评分研究组均显著高于对照组（P<0.05）；治疗后，两组DA、NE、ChAT水平均升高，且研究组明显高于对照组（P<0.05）；治疗后，两组SOD水平升高，APP、Aβ1-42、MDA水平均降低（P<0.05），且与对照组相比研究组各指标变化更显著（P<0.05）；两组治疗期间的不良反应均较轻微，经对症处理后均缓解，不良反应发生率比较无明显差异（P>0.05）。结论：自拟益气通阳活血方治疗阿尔茨海默病疗效显著，可降低中医证候积分，提高认知功能，调节NE、DA、ChAT水平，抑制APP、Aβ1-42水平，提高其日常生活活动能力，且安全性高。     

Abdominal vagotomy does not block the satiety effect of bombesin in the rat

Bombesin (2-16 microgram-kg-1, intraperitoneally) inhibited food intake in rats after abdominal vagotomy. Since the same vagotomized rats did not respond to the octapeptide of cholecystokinin (1-8 micrograms-kg-1, intraperitoneally), these data are decisive evidence (1) that bombesin does not produce satiety by releasing endogenous cholecystokinin and (2) that vagal afferents are not necessary for the satiety effect of bombesin.     

Foraging tactics in alternative heterochronic salamander morphs: trophic quality of ponds matters more than water permanency

1. In lentic freshwater habitats, the composition of animal assemblages shifts along a gradient from temporary to permanent basins. When habitats with different degrees of permanence are at the scale of the home range of species, they constitute alternatives in terms of energy acquisition through feeding. 2. In this context, previous studies showed an advantage of metamorphic over paedomorphic tiger salamanders (Ambystoma tigrinum) in temporary ponds which are only available to metamorphs. The aim of this study was to establish whether salamanders obtain similar benefits in ponds that do not differ in water permanence and whether salamanders shifted from detrimental to advantageous ponds. To this end, we determined the feeding habits, body condition and movement patterns of the two morphs in a complex of four permanent and four temporary ponds. 3. Consistent with previous studies, metamorphs consumed higher‐quality diets than paedomorphs in term of energy intake. However, these differences occurred because metamorphs consumed fairy shrimp in a single temporary pond. Individual movement patterns confirmed that most of the metamorphs used different aquatic habitats both within and between years and that most of them moved from permanent ponds for breeding towards the most profitable temporary pond in terms of foraging. 4. These results indicate that habitat selection by salamanders is optimal in term of energy intake in metamorphs that use high quality ponds independently of hydroperiod. It seems that both spatial and temporal variation can influence the relative foraging success of each morph.