Animal - Open Space最新文献

This study investigated the repeatability and influences of the time of the day (TOD) and horn status on cortisol responses to ACTH administration in heifers. Sixty-four heifers were subjected to three ACTH challenges. The first challenge (C1) took place at the age of 2 mo. Balanced for peak cortisol responses at C1, the heifers were assigned to one of two rearing conditions: horned (H+) or disbudded (H−). At the age of 15 months, the second (C2) and third (C3) challenges took place, 7 d apart from each other at the same TOD. For cortisol analysis, saliva was sampled in 30-min intervals from 30 min before to 150 min after each ACTH injection. The area under the curve (AUC) of cortisol was calculated with respect to the ground (AUC_G) and to the increase (AUC_I). Between C2 and C3, AUC values did not differ (P > 0.10), intra-class correlation coefficients (ICCs) indicated poor repeatability (AUC_G: ICC = 0.24 and AUC_I: ICC = 0.26) and no correlations were found. The TOD had no effect on AUC values in C2 (P > 0.1), while in C3, they were greater in the morning than in the afternoon (for both AUC_G and AUC_I, P < 0.05). The H+ and H− heifers showed similar cortisol responses in C3, but in C2, horned heifers had greater AUC levels (P < 0.05). From C2 to C3, AUC values increased and decreased for heifers tested in the morning and afternoon, respectively. This was more pronounced in H+ than in H− heifers (interaction effect P <0.05). The results indicate poor to lacking repeatability for ACTH challenges performed within the same physiological state. While TOD and horn status partly contributed to the cortisol responses’ variance, the poor repeatability critically questions the use of repeated ACTH challenges for stress research in cattle.

Coccidiosis is one of the major challenges in the poultry industry, leading to reduced animal performance and welfare and increased mortality. Currently, ionophores and chemicals are used to treat coccidiosis. However, the outbreak of resistant Eimeria strains and the growing customer demand for more sustainable products have prompted the need to identify nutritional strategies for coccidiosis control. In this study, we reviewed the efficiency of the supplementation of a combination of functional amino acids (arginine, threonine and glutamine) with grape extract polyphenols in broilers challenged with coccidiosis via a meta-analysis based on five independent trials. We observed that supplementation partially improved the performance of broilers affected with coccidiosis when compared with infected, untreated animals. In addition, there was no significant difference between the effect of supplementation of the combination of functional amino acids with grape extract polyphenols and that of anticoccidial drugs on animal performance when considering the overall trial period. This meta-analysis suggests that supplementing with a combination of functional amino acids with grape extract polyphenols could improve performance in broilers affected with coccidiosis. However, further research to understand the mechanisms involved is needed.

Because of their intense metabolism, lactating sows are highly sensitive to high ambient temperature which induces a reduction in their voluntary feed intake and milk production, which decreases piglet weaning weight. This also results in an increase in mobilisation of body reserves that may impair reproduction after weaning. The aim of the study was to quantify, on the basis of a quantitative analysis of the literature data, the effect of ambient temperature on the performance and physiology of lactating sows, with the perspective of integrating this knowledge in sow nutrition decision support tools. A literature database with 38 publications and a total of 227 observations was built in order to adjust prediction equations according to temperature, using a Mixed linear or quadratic model with random effect of publication, for different criteria such as feed intake, litter and piglet growth rate, milk production, maternal body reserve mobilisation, respiratory rate (RR) and core body temperature. The first criterion with the highest response to temperature was RR which increased by 175 % between 22 °C and 32 °C. The second most affected criterion was feed intake which was reduced by 36 % between 22 °C and 32 °C, and the third one was milk production which was reduced by 20 % between 22 °C and 32 °C. The equations obtained from the meta-analysis were incorporated into a nutrition model, based on InraPorc®, in order to predict, in the context of climate change, the effect of temperature on feed intake, milk production, energy and aminoacid utilisation, and body reserve mobilisation. The simulations performed using this model clearly indicate that nutrient requirement of sows per kg feed is affected by variation in ambient temperature due to seasons or to expected climate change. In practice, the integration of these new equations in nutritional models will enable feed composition to be better adapted to the season and to the geographical location of farms.

To evaluate the effect of dietary protein level (13.0% and 9.5% CP) and duration of fasting on the enzymatic activity of cathepsin B in live muscle and pig, 44 fattening pigs weighing 138 ± 9 kg were reared to slaughter (171 ± 9 kg). The feed allowance was set at 3.2 kg/day. Two weeks prior to slaughter, subjects on each diet were randomly assigned to one of two different fasting treatments (no fasting or 48 h fasting). After this treatment, an individual longissimus dorsi (LD) muscle sample was taken from each pig by biopsy at the level of the third lumbar vertebra and frozen in liquid nitrogen until analysis. Then, the subjects within each diet × fasting interaction were assigned to different fasting times before slaughter (4 or 28 or 52 h). One day after slaughter, LD and semimembranous muscle (SM) samples were taken from each carcass, kept at 4 °C for 24 h and then frozen in liquid nitrogen. The activity of cathepsin B was measured in muscle homogenates by colorimetric method. Dietary CP did not affect cathepsin activity in LD obtained in vivo and daily live weight gain up to slaughter. Compared to the absence of fasting, a cathepsin activity greater than 18% in LD was observed after 48 h of fasting (P < 0.01). Cathepsin activity in LD and SM sampled after slaughter was not affected by dietary protein level and fasting 2 weeks prior to slaughter. Compared with 28 h fasting, feeding exclusion for 52 h prior to slaughter increased cathepsin activity in the LD and SM muscles by 18% (P < 0.05) and 12% (P = 0.07) respectively. The preslaughter fasting length had no effect on fresh meat quality parameters (pH at 1 and 24 h post mortem, colour, drip losses, cooking losses).

The fasting heat production (FHP; net energy expenditure under maintenance) is a key value to determine the net energy value of the feed and is calculated from measurements in respiratory chambers or predicted as a function of the metabolic BW (MBW). This study aimed to determine the influence of body composition on the FHP of broilers through a modeling approach. Six experiments (Exp 1–6) were conducted to develop (Exp 1–4) and externally validate (Exp 5 and 6) predictive models. In Exp 1–4, broilers of a single genetic line in floor pens were subjected to three dietary treatments to induce differences in body composition. The FHP (calorimetry chambers) and the body protein-to-fat ratio (PFR; Dual-Energy X-ray Absorptiometry) were recorded at nine time points between 7 and 55 days. Linear models were adjusted (considering the pen as the experimental unit), starting with a model containing the MBW as the sole predictor. Further modifications were tested by including the PFR and the age of the birds. A random split with a refitting approach was applied. Four models were internally validated and refitted to the whole data. They considered the FHP a function of the MBW (or BW) and the PFR, including or not the age of the birds, and showed high precision (R² > 0.98) and accuracy (error < 2.5%). All models demonstrated that birds at the same BW and age have higher FHP the leaner they are. Body protein and fat are positively and negatively correlated to FHP, respectively. In Exp 5, broilers of two genetic lines fed three dietary treatments were tested for FHP and body composition at 22 and 41 days. In Exp 6, broilers fed continuous dietary treatments in a dose–response design were tested for FHP and body composition at 17, 20, and 41 days. The models were tested on the data from Exp 5 and 6 considering the treatments as the validation unit. The four selected models showed high prediction precision (validation R² > 0.92) and accuracy (model prediction error < 3%) and were validated externally. In conclusion, at the same age and BW, the higher the PFR, the higher the FHP. Including the PFR improved the strength of the models.

A dataset of 100 pigs, from the Piétrain NN Français line raised at the AXIOM boar testing station in 2020, was used. The farm was equipped with an automatic feeding system, recording individual weight and feed intake at each visit. We used a dynamic linear regression model to characterise the evolution of the energetic allocation factor (α_t) which represents the link between the cumulative net energy available (estimated from feed intake) and cumulative weight gain during the fattening period. The data were imported using an R script to estimate the allocation factor for a given animal. The dataset and R script are useful resources to study feed intake, growth dynamics and the relationship between these two variables.

The aim of this study was to investigate the effects of gradually increased dietary CP level on the dynamics of individual egg production of laying hens from 18 to 54 weeks of age. Forty Hy-Line Brown hens were divided into five treatments of eight replicates each and were fed diets formulated to have five different CP concentrations: 14, 15, 16, 17, and 18% CP with the same energy content. For each experimental diet, the contents of lysine, methionine + cysteine, threonine, and tryptophan were maintained at minimum requirement concentrations by supplying synthetic amino acids. Clutch characteristics were recorded (e.g., number, size, patterns, egg weight, etc.) and individual egg production curves were modeled according to Grossman and Koops (2001). Clutch size was defined as the unstopped length of individual egg production on a daily basis. BWs were also recorded every week to account for changes in BW during the experimental period. Three hens were excluded from the statistical analyses as their laying patterns were very inconsistent. Four clutch patterns with data weighted on a weekly basis were identified. Heavier hens tended to lay more regular clutch patterns when compared to their lighter counterparts within the same treatment. In contrast, irregular clutch patterns (too many pauses between clutches) were more common in hens fed low CP diets (≤16%). This could be explained by imbalances in amino acids supply according to their theoretical requirements and adverse effects caused by amino acids interactions. Low CP diets were able to maintain egg production and mean clutch size up to 54 weeks of age. The maximum clutch size and the modeled proportion of maximum production for the increasing phase (k₁) displayed a linear response to the graded addition of CP content to the diet. No differences were detected among treatments for the age at the beginning of the maximum clutch (22.6 ± 2.82 weeks). Egg weight displayed a quadratic response that was maximized when hens were fed 17% CP in the diet. Our approach appears to be promising for ranking individual laying hens based on their clutch performance to evaluate both CP and amino acids adequacy of diets.

Antimicrobial growth promoters (AGPs) have been banned from animal husbandry owing to their association with the occurrence of bacterial resistance. Although the mechanism of action of AGP is still unknown, it is believed to be related to an anti-inflammatory action in the gastrointestinal tract. In this context, the aim of the present study was to establish if supplementation of broiler feed with the non-steroidal anti-inflammatory sodium salicylate (SS) induces adverse effects related to this class of drug and to evaluate the potentiality of SS in improving the zootechnical indices of broilers. One-day-old Cobb 500 male chicks were divided into four groups (12 per group) and treated over a period of 42 days with non-supplemented feed (control group) or with feed to which doses of 2.5, 5.0, or 10.0 mg of SS/kg BW were added daily. Feed intake and BW were assessed and haematological, biochemical, and histopathological alterations were evaluated throughout the experiment. Whereas no statistical differences in food intake or BW were detected between the groups, a 5.8% increase in total BW gain was observed in broilers treated with 10 mg of SS/kg BW. In addition, the highest dose of SS studied generated the lowest total feed conversion rate over the experimental period in comparison with all other SS treatment groups. Haematological and biochemical evaluations did not reveal any altered parameters that could be related to the adverse effects of SS. No renal or hepatic alterations were detected in the histopathological study of tissue collected on day 42, and no lesions or ulcerations were observed in the gastrointestinal tract. We conclude that daily doses of SS in the range of 2.5–10 mg/kg BW can be added safely to broiler feed for 42 days, and that this non-steroidal anti-inflammatory drug is promising for future studies of its use as a growth-promoting agent.

Irregular milking intervals in automated milking systems contribute to additional variation in daily milk yield records in comparison to those derived from systems using regular milking intervals. Various methods have been developed to estimate 24-h adjusted milk yields, though they are not well suited for the evaluation of serial milk yield data, particularly when milking intervals span calendar days. The objective of this study was to develop a methodology to estimate serial 24-h milk yields by adjusting for irregular milking intervals. Using data collected from an automated milking system (AMS), the total yield at a given milking event and the elapsed time from the previous entry into the AMS were used to calculate the milking interval and the average rate of milk secretion over that interval. Milking intervals and associated milk secretion rates were then realigned to calendar days to allow the proportional distribution of milk yield when milking intervals spanned more than one day. Using this method, variation in daily milk yield was decreased and adjusted estimates of 24-h milk yield were visually more similar to those typically observed in milking systems with regular milking intervals. Estimates of interval-adjusted milk yields were strongly correlated to those calculated using moving averages, suggesting that this method can yield comparable results to established methods for estimation of test-day milk yield.

The increasing breast weight of modern broilers highlights the convenience of studying the dynamics of processing weights across the grow-out period. For models predicting these traits to work with non-fasted live birds under longitudinal studies, it is necessary to determine the changes in the weights of birds due to fasting and bleeding and carcasses due to chilling. This study aimed to develop a model to predict the fasting weight loss of broilers, determine the weight changes due to bleeding and chilling, and assess the percentage of gizzard fat in the abdominal fat. Models were fitted to fasting BW loss data from literature. A bleeding BW loss value obtained in a pilot study was compared to literature. This one and a single-source percent gizzard in the abdominal fat value were used as reference values. Birds from two experiments were selected at different ages to determine the following variables: non-fasted and fasted BW, bled weight, unchilled and chilled carcass weights, and gizzard fat and abdominal fat pad weights. Predicted and reference values were compared to the observed data based on their 95% confidence intervals, and the fitted model and reference values were validated if no statistical differences were inferred. The fasting BW loss model was refitted to the data from experiments, and the estimates of the model fitted to both datasets were compared. The fasting BW loss followed a three-parameter exponential model with reducing values as the bird aged, and the predicted and observed values showed no statistical difference (P > 0.05). The reference bleeding BW loss (2.76%) and gizzard fat percentage (18%) values showed no difference (P > 0.05) to data from broiler experiments, and a chilling carcass weight gain of 2.79% was determined. The scale and relative growth rate estimates of the fasting BW loss model showed no difference (P > 0.05) between datasets, and the asymptote showed a possible but negligible difference. The fasting BW loss model, the bleeding BW loss coefficient, and the gizzard fat percentage were validated. The model and coefficients obtained herein will not only be applied to predict processing weights using Dual-Energy X-ray Absorptiometry but also may be used in other modeling approaches.