Camelina sativa cake for broiler chickens: effects of increasing dietary inclusion on clinical signs of toxicity, feed disappearance, and nutrient digestibility

The effect of feeding diets with increasing dietary inclusions of Camelina sativa cake (CC; 22% ether extract, 34% crude protein) on safety, feed disappearance, and nutrient digestibility was evaluated in a 42-day (d) broiler study. Day-old male chicks (Ross 308; n = 744) were divided among 24 test cages in a randomized complete block design with six replicate cages per dietary regimen. Dietary regimens consisted of feeding test diets containing 0, 8, 16, or 24% CC over three growth phases of 2-week duration each. Diets fed from d 14–21 included an indigestible marker. Pen body weight, feed added, and leftover orts for each phase were measured on d 0, 14, 28, and 42 to calculate average daily feed disappearance, average daily weight gain, and gain-to-feed ratio. On d 14, 28, and 42, three broilers per test cage were euthanized by intravenous injection. A gross post mortem examination was conducted and select organs were weighed. Blood was drawn from broilers removed on d 42 to measure serum parameters. Excreta from d 19 to 21 and ileal digesta (10 birds per cage) on d 21 were collected to yield a single pooled sample of each per test cage. Dietary CC inclusion up to 24% did not affect broiler mortality or the incidence of abnormal gross findings. Differences (P < 0.05) in serum levels of P, uric acid, T3, and T4 are explained by differential digestible nutrient intake among broilers fed increasing CC inclusion levels. Organ weight as proportion of body weight was not affected by treatment, except for pancreas on d 28 and 42, which both linearly increased (P < 0.01) with increasing CC inclusion. Daily feed disappearance did not differ among CC inclusion levels for the overall 42-d study. Increasing dietary CC inclusion level linearly reduced nutrient digestibility of test diets (P < 0.01). In conclusion, CC is a safe feedstuff for broilers that can be fed at dietary inclusions up to and including 24% without adverse effects on broiler health.

Behavioural Variability in Chicks vs. the Pattern of Behaviour in Adult Hens

The aim of the study was to assess the behaviour of chicks of three different breeds of laying hens differing in the activity, emotional reactivity, and environmental preferences. Another objective was to answer the question whether the behavioural differences between adult birds would be evident already in the chick period or whether they are an effect of the further modifying impact of the environment. 60 green-legged partridge, 60 Polbar, and 60 Leghorn chicks were used in the experiments. The chicks hatched in a flock where hens were previously assessed with behavioural tests and the corticosterone levels in their feathers was determined, indicating significant differences in the temperament and stress level between the breeds. Five tests were carried out: two on competitiveness, activity, interest and fearfulness/curiosity. The experiments revealed considerable differences between the chicks. The Zk birds coped better with situations requiring swiftness and initiative. The Pb chicks were slower than Zk and Lg and did not make quick decisions. Hence, a lower number of these birds entering and leaving the test cage and staying inside was recorded. The Zk chicks exhibited a higher level of fearfulness than the other breeds. In terms of the environment enrichment elements, sand and woodchips were more attractive to the Zk chicks, whereas the Lg and Pb birds preferred pecking the string. No differences in the time of undertaking the analysed activities were found between the breeds.

Memory for the Spatial Position of an Imprinting Object in Junglefowl Chicks

The characteristics of memory for the position of an imprinting object were investigated in junglefowl chicks (Gallus gallus spadiceus). Subjects were exposed individually and continuously to an imprinting object located in one of the two back quadrants of their home cage ('training quadrant'). Positioning of chicks in a test cage was studied from 7 to 1 days after hatching. In experiment 1 chicks preferred the training quadrant over the other back quadrant when tested in an empty cage, but not when two identical training objects were present, one in each back quadrant. In tests with one training object present, chicks showed more shrill calling when the object was in a novel position than when it was in the training position, but only during the first minute of a 5-min test. The strength of position preferences was independent of the effectiveness of the training object as an imprinting stimulus. In experiment 2a, chicks switched the position preference in an empty cage from the training quadrant to the other back quadrant after 2 h of exposure to the training object in that back quadrant of the home cage. In experiment 2b however, chicks still preferred the original training shape to a novel shape, after 2 h of exposure to an object with that novel shape. These results show that position memory in filial behaviour is less stable than memory for the physical properties of the imprinting object, and that position responses occur when chicks are motivated to seek contact with the object.