Conditions influencing the appearance of thermal windows and the distribution of surface temperature in hauled-out southern elephant seals.

Pinnipeds (true seals, sea lions and walruses) inhabit two thermally different environments, air and water, so need to make continuous adjustments to maintain a balanced body temperature. The thermal isolation properties of thick blubber keep warmth within the body's core, ideal for mammals while in the water; however, when on land, this thick blubber makes it difficult to lose heat. Some pinnipeds use thermal windows, discrete patches where temperature changes on their body surface, as a mechanism to dissipate excessive heat. We identify the factors that correlate with the appearance of thermal windows and changes in body surface temperature on southern elephant seals, Mirounga leonina, while they are hauled out ashore. Infrared thermography was used to measure surface temperature of the seals. Temperature was lower on the torso than the flippers and head, suggesting that not all body sites have the same role in thermal balance. Air temperature was the main driver of variation in the surface temperature of the seals' flippers and head; seals cool their superficial tissues when the air temperature is below ~ 2°C. This minimizes heat loss by reducing the thermal gradient between their skin and the ambient air. Wind speed was the main predictor of whether thermal windows appear on a seals' body surface. When wind speed was minimal, thermal windows occurred more often, which may be associated with either hair and skin drying, or producing thermal conditions for hair and skin regrowth. The type of aggregation (huddled or alone) influenced the surface temperature of the fore flippers; however, we did not find statistical influence of the seal's sex, state of moult, or the substrate on which they were hauled out (kelp or sand). Understanding how animals maintain their thermal balance is important if we are to predict how they will respond to future climate change.

Participation of Na+/K+-ATPase and aquaporins in the uptake of water during moult processes in the shrimp Palaemon argentinus (Nobili, 1901).

Due to the presence of the exoskeleton, the moult cycle is a required event in the life of crustaceans. In order for the exoskeleton to be replaced, it is necessary for these animals to uptake water from the environment for their body tissues during the late pre-moult, ecdysis and in the early post-moult for the expansion of the new cuticle. The mechanisms and organs used to uptake water in these events are not yet completely clear. In this study, we investigated the participation of aquaporins and Na+/K+-ATPase in cells of two potential organs responsible for the uptake of water (gills and gut) at three different stages of the moult cycle in freshwater shrimp Palaemon argentinus. We showed the participation of these two proteins with different functional patterns in gills and intestinal cells as water uptake pathways for moult and early post-moult. Our results indicate that Na+/K+-ATPase promotes the necessary osmotic gradient in the gills for water uptake through the gut cells during the pre-moult. This process, in turn, remains active during the post-moult stage with the addition of water influx through the gill cells.

Temporal variations of body mass and plumage in Arenaria interpres (Aves: Scolopacidae) along the Brazilian coast

Every year, Brazil receives large flocks of nearly 40 migratory shorebirds species. The accumulation of body fat and nutrients during the summer is necessary for the long return flights of these birds and is fundamental for feather moulting and the change of their plumage. We present here an examination of the relationship between body mass and plumage change in Arenaria interpres (Linnaeus, 1758), one of those birds, over time during its wintering period on the Brazilian coast. We analyzed information collected at five traditional stopover sites along the Brazilian coast, between 1997 and 2007. During the month of September, individuals with intermediate or breeding plumage had smaller body masses as compared to other months. From October to December, adult individuals were only observed with eclipse plumage and had average body masses of approximately 100 g. In March, individuals with intermediate, eclipse and breeding plumages were recorded, but their average body mass remained at approximately 100 g. In April and May the numbers of individuals with breeding or intermediate plumage increased, and they showed significant increases in body mass at a rate of approximately 1.5 and 2.3 g per day, in the north-northeastern and south coast, respectively, leading to an average mass of 124 and 143g in these months. That is suggested to be the departure mass of A. interpres in the Brazilian north-northeastern and south coast, respectively, when starting the migration to the breeding sites.

Temporal variations of body mass and plumage in Arenaria interpres (Aves: Scolopacidae) along the Brazilian coast

Every year, Brazil receives large flocks of nearly 40 migratory shorebirds species. The accumulation of body fat and nutrients during the summer is necessary for the long return flights of these birds and is fundamental for feather moulting and the change of their plumage. We present here an examination of the relationship between body mass and plumage change in Arenaria interpres (Linnaeus, 1758), one of those birds, over time during its wintering period on the Brazilian coast. We analyzed information collected at five traditional stopover sites along the Brazilian coast, between 1997 and 2007. During the month of September, individuals with intermediate or breeding plumage had smaller body masses as compared to other months. From October to December, adult individuals were only observed with eclipse plumage and had average body masses of approximately 100 g. In March, individuals with intermediate, eclipse and breeding plumages were recorded, but their average body mass remained at approximately 100 g. In April and May the numbers of individuals with breeding or intermediate plumage increased, and they showed significant increases in body mass at a rate of approximately 1.5 and 2.3 g per day, in the north-northeastern and south coast, respectively, leading to an average mass of 124 and 143g in these months. That is suggested to be the departure mass of A. interpres in the Brazilian north-northeastern and south coast, respectively, when starting the migration to the breeding sites.

Temporal variations of body mass and plumage in Arenaria interpres (Aves: Scolopacidae) along the Brazilian coast

Every year, Brazil receives large flocks of nearly 40 migratory shorebirds species. The accumulation of body fat and nutrients during the summer is necessary for the long return flights of these birds and is fundamental for feather moulting and the change of their plumage. We present here an examination of the relationship between body mass and plumage change in Arenaria interpres (Linnaeus, 1758), one of those birds, over time during its wintering period on the Brazilian coast. We analyzed information collected at five traditional stopover sites along the Brazilian coast, between 1997 and 2007. During the month of September, individuals with intermediate or breeding plumage had smaller body masses as compared to other months. From October to December, adult individuals were only observed with eclipse plumage and had average body masses of approximately 100 g. In March, individuals with intermediate, eclipse and breeding plumages were recorded, but their average body mass remained at approximately 100 g. In April and May the numbers of individuals with breeding or intermediate plumage increased, and they showed significant increases in body mass at a rate of approximately 1.5 and 2.3 g per day, in the north-northeastern and south coast, respectively, leading to an average mass of 124 and 143g in these months. That is suggested to be the departure mass of A. interpres in the Brazilian north-northeastern and south coast, respectively, when starting the migration to the breeding sites.

Performance and egg quality of strains of laying hens after forced molt with different levels of calcium / Desempenho e qualidade dos ovos de diferentes linhagens de poedeiras comerciais pós-muda forçada recebendo rações com níveis variáveis de cálcio

One experiment was conducted to study performance of laying hens of four strains after forced molt: Lohmann White, Babcok, Embrapa-011 (light weight) and Lohmann Brown (semi-heavy weight). Different levels of calcium were applied during the production period (2, 3, 4, 5 and 6%), the experimental design was a random block design with whole 400 birds. Hens were 74 week old at the beginning of the molt phase. The birds fed 2% of calcium showed lower feed consumption and lower egg production. The highest levels of calcium increased the egg shell quality. The color of egg yolk was lower for levels 2 and 6% of calcium. Egg weight, Haugh unit and egg yolk color were related to strain, and the Embrapa-011 showed the lower performance among strains.

O experimento foi conduzido com o objetivo de comparar o desempenho produtivo de poedeiras, de 4 linhagens (Lohmann White, Babcock, Embrapa-011 e Lohmann Brown), pós-muda forçada recebendo diferentes níveis de cálcio nas rações (2, 3, 4, 5 e 6%). O delineamento experimental foi em blocos ao acaso, sendo utilizadas 100 aves por linhagem, com 74 semanas de idade. As aves que receberam 2% de cálcio apresentaram menor consumo de ração e produção de ovos; os maiores níveis de cálcio aumentaram a qualidade da casca dos ovos. A cor da gema foi menor para os níveis 2 e 6%. As variáveis peso dos ovos, Unidades Haugh e cor da gema foram relacionadas com a linhagem, e a Embrapa-011 apresentou o pior desempenho entre as linhagens.