Physiological and behavioural effects of intermittent fasting vs daily caloric restriction in meat-type poultry.

Intermittent fasting (IF) is the practice of temporal food restriction to promote metabolic switching between a glucose- and a ketone-based metabolism, which has been reported to come with diverse health benefits. IF practices appear to confer many of the advantages of caloric restriction without restricting total energy intake, and studies in both rodents and humans suggest organism-wide improvements in neurological, cardiovascular and metabolic health. IF is also commonly employed in the commercial rearing of breeding meat-type poultry, i.e. broiler breeders, which require strict feed restriction throughout life to maintain physical health. While the scientific poultry literature holds vast amounts of data on such "skip-a-day" feeding schedules, it has been unclear to what extent avian and mammalian literature may be compared as broiler breeders are typically feed-restricted to around 30% of ad libitum intake even in IF schedules. In this study, we set out to disentangle the effects of IF and caloric restriction in meat-type poultry by employing both IF and daily feeding schedules at two different restriction levels. Our results suggest that the physiological response to IF in chickens is only marginally affected by the intensity of feed restriction, while behavioural parameters are more closely related to feeding level and are expected to better mirror animal welfare. Our results suggest that avian and mammalian literature on IF should be comparable. Meat-type chickens do show some peculiarities in response to IF, such as a reduced insulin sensitivity, but it is currently unclear whether this is true for all chickens or is an effect of the intense selection for rapid growth in meat-type chickens.

Refeeding ewes ad libitum after a moderate energy restriction during mid gestation did not affect the onset of breeding and ovulating rate of female offspring.

Sub-nutrition during pregnancy might affect the offspring´s reproductive performance through effects on the development and function of gonads. This study evaluated a maternal energy restriction in ewes from day 48-106 of gestation, on pre- and post-weaning female lambs` performance, onset of female lambs' breeding and ovulation rate during their first breeding season. Adult Polwarth ewes sired by Finnish rams bearing single or twin lambs were assigned to two dietary treatments from day 48 to day 106 of gestation: restricted (R; n = 60) at 60 % of their metabolizable energy (ME) requirements, or non-restricted (NR; n = 54) at 100 % of their ME requirements. After the restriction period, ewes grazed all together ad libitum until weaning. The ewe lambs were evaluated from birth to weaning, as well as during their first breeding season. Although NR ewes weighed 17.7 % more than R ewes (P < 0.05) at the end of the restriction period, the nutritional treatment of the dams had no effect on the weight of the ewe lambs at birth, weaning or final weight (P > 0.05). Fat depth, rib eye area, the percentage of ewe-lambs cycling and their ovulation rate during the first breeding season was not affected by the ewe´s dietary treatment. Ewes restricted at 60 % of their ME requirements in mid-gestation seemed to have the capacity to compensate any detrimental effects on growth and development as well as the reproductive potential of female lambs if adequate refeeding conditions are provided in late gestation, throughout lactation and post-weaning.

Nutritional restriction during the peri-conceptional period alters the myometrial transcriptome during the peri-implantation period.

This study hypothesized that female peri-conceptional undernutrition evokes transcriptomic alterations in the pig myometrium during the peri-implantation period. Myometrium was collected on days 15-16 of pregnancy from pigs fed a normal- (n = 4) or restricted-diet (n = 4) from conception until day 9th of pregnancy, and the transcriptomic profiles of the tissue were compared using Porcine (V2) Expression Microarrays 4 × 44 K. In restricted diet-fed pigs, 1021 differentially expressed genes (DEGs) with fold change ≥ 1.5, P ≤ 0.05 were revealed, and 708 of them were up-regulated. Based on the count score, the top within GOs was GO cellular components "extracellular exosome", and the top KEGG pathway was the metabolic pathway. Ten selected DEGs, i.e. hydroxysteroid (17ß) dehydrogenase 8, cyclooxygenase 2, prostaglandin F receptor, progesterone receptor membrane component 1, progesterone receptor membrane component 2, annexin A2, homeobox A10, S-phase cyclin A-associated protein in the ER, SRC proto-oncogene, non-receptor tyrosine kinase, and proliferating cell nuclear antigen were conducted through qPCR to validate microarray data. In conclusion, dietary restriction during the peri-conceptional period causes alterations in the expression of genes encoding proteins involved i.a. in the endocrine activity of the myometrium, embryo-maternal interactions, and mechanisms regulating cell cycle and proliferation.

What are the limits to feed intake of broilers on bulky feeds?

The view that genetic selection for carcass yield has limited the size of the gastrointestinal tract (GIT) of modern broilers has sparked concerns that their capacity to cope with energy dilution or bulk is also limited. We investigated the capacity of male Ross 308 broilers to deal with increasing levels of bulk and aimed to identify a feed bulk dimension responsible for limiting feed intake (FI). About 528 day-old broilers were allocated to 48 pens and offered a common starter feed until day 8, and 1 of 7 feeds from day 8 to 36 of age: a basal control (B), which was diluted to 3 levels (15, 30, or 45%) with either oat hulls (OH) or sugar beet pulp (SBP). Feed intake was measured daily and birds were dissected for GIT measurements at day 15, 22, and 36. Feed intake increased in birds offered OH15 (135 g/d), OH30 (140 g/d), and SBP15 (138 g/d) compared with birds offered the B feed (106 g/d; SEM 2.4). By increasing FI, birds were able to compensate for the lower energy content of their feeds. The greatest increase in FI was seen on OH30: its energy content (2,273 kcal/kg) was 26% lower than the B feed (3,081 kcal/kg). There was evidence of adaptation on the bulky feeds, as during the last week only birds on SBP45 were limited in FI and performance. The relative weights of the GIT were greater in the SBP than OH series, suggesting that the former needed to accommodate a higher bulk intake. For the OH series the increase in the relative GIT weights was confined to the gizzard and small intestine; whereas for the SBP series, the increase was extended to proventriculus and large intestine. Because only SBP45 was limiting FI, we were unable to identify a bulk dimension to be used to predict FI. Our data reject the suggestion that modern broilers have a reduced ability to cope with reductions in feed energy content.

Performance of broiler chicken submitted to a quantitative feed restriction program.

The search for better zootechnical indexes such as feed conversion, daily weight gain, uniformity, and lower bird mortality has become a priority within the poultry industry. The use of food restriction programs has emerged as an alternative to improve these rates as well as to mitigate the effect of the increased cost of nutrition over the past few years. In this work, the feed conversion (FC), daily weight gain (DWG), uniformity, and mortality of male broilers submitted to two food restriction programs were evaluated; one program reduced food by 10% and the other by 20% in relation to the feeding program suggested by the Cobb500 strain. One hundred and eighty birds aged 10 days old were housed in 12 boxes for 30 days. Fifteen birds were placed in each box, and four replicates per treatment were designed: T1 (control group-feed intake as recommended by the Cobb500 strain), T2 (10% reduction), and T3 (20% reduction). There was no statistical difference in DWG, uniformity, or mortality between the treatment groups. As for FC, a statistical difference was observed with a gain of 100 g in T2 and 252 g in T3 in relation to T1. The results of this work demonstrate that food restriction programs can be used to improve FC in broiler flocks, without interfering with the DWG, uniformity, or mortality of birds.

Influência da restrição alimentar e do estresse térmico sobre parâmetros fisiológicos em ovinos / [Influence of food restriction and heat stress on physiological parameters in sheep]

Objetivou-se avaliar as alterações fisiológicas de ovinos submetidos à restrição alimentar, expostos à radiação solar e à sombra. Dez borregas mestiças foram divididas igualmente em dois grupos: grupo radiação solar - GRS, animais expostos ao sol durante o dia; e grupo sombra - GS, animais alocados dentro de um galpão à sombra. Nos seis dias iniciais de experimento, os animais foram submetidos à restrição alimentar, com acesso apenas à água, já expostos ao sol ou à sombra. Nos seis dias subsequentes, foi ofertada dieta composta por ração e feno de alfafa (3%PV). Os parâmetros avaliados foram frequência respiratória (FR), temperatura retal (TR), ß-hidroxibutirato (BHB), pH urinário, ingestão de matéria seca (IMS) e dados bioclimáticos (temperatura, umidade relativa do ar e índice de temperatura e umidade - ITU). A FR foi o parâmetro em que houve maior diferença significativa entre os grupos (p<0,05). O balanço energético negativo foi constatado em todos os animais (BHB>0,8mmol/L; pH<7,0). Ovelhas que sofrem restrição alimentar durante períodos de alta temperatura e umidade têm menor frequência respiratória e temperatura interna, independentemente de estar na sombra ou pleno sol. Porém, quando normalizado a oferta de alimento as ovelhas em pleno sol têm menor ingestão de matéria seca.(AU)

We aimed to evaluate physiological changes in sheep submitted to food restriction, exposed to the sun or shade. Ten ewe lambs were equally divided into two groups: Sun Radiation Group - GRS, exposed to sun during day hours, and Shade Group - GS, with animals placed inside a barn. In the first six days of experiment, animals were submitted to food restriction, with access to fresh water, already exposed to sun and shade. In the following six days alfalfa hay and concentrate were provided to the animals (3%BW). Parameters assessed were respiratory rate (FR), rectal temperature (TR), ß-hydroxybutyrate, urinary pH, dry matter intake (IMS) and climate data (air temperature, humidity, and temperature-humidity index - ITU). The parameter that most differed between groups was FR. All animals presented negative energy balance (BHB>0.8mmol/L; pH<7,0). Ewe lambs submitted to food restriction during periods of high temperature and humidity have lower respiratory rate and intern temperature, independently of being exposed to sun or shade. However, when food was offered animals exposed to sun had lower dry matter intake.(AU)

Genome-wide association study for feed efficiency in collective cage-raised rabbits under full and restricted feeding.

Feed efficiency (FE) is one of the most economically and environmentally relevant traits in the animal production sector. The objective of this study was to gain knowledge about the genetic control of FE in rabbits. To this end, GWASs were conducted for individual growth under two feeding regimes (full feeding and restricted) and FE traits collected from cage groups, using 114 604 autosome SNPs segregating in 438 rabbits. Two different models were implemented: (1) an animal model with a linear regression on each SNP allele for growth trait; and (2) a two-trait animal model, jointly fitting the performance trait and each SNP allele content, for FE traits. This last modeling strategy is a new tool applied to GWAS and allows information to be considered from non-genotyped individuals whose contribution is relevant in the group average traits. A total of 189 SNPs in 17 chromosomal regions were declared to be significantly associated with any of the five analyzed traits at a chromosome-wide level. In 12 of these regions, 20 candidate genes were proposed to explain the variation of the analyzed traits, including genes such as FTO, NDUFAF6 and CEBPA previously associated with growth and FE traits in monogastric species. Candidate genes associated with behavioral patterns were also identified. Overall, our results can be considered as the foundation for future functional research to unravel the actual causal mutations regulating growth and FE in rabbits.

Comparison between Tibetan and Small-tailed Han sheep in adipocyte phenotype, lipid metabolism and energy homoeostasis regulation of adipose tissues when consuming diets of different energy levels.

This study aimed to gain insight into how adipose tissue of Tibetan sheep regulates energy homoeostasis to cope with low energy intake under the harsh environment of the Qinghai-Tibetan Plateau (QTP). We compared Tibetan and Small-tailed Han sheep (n 24 of each breed), all wethers and 1·5 years of age, which were each divided randomly into four groups and offered diets of different digestible energy (DE) densities: 8·21, 9·33, 10·45 and 11·57 MJ DE/kg DM. When the sheep lost body mass and were assumed to be in negative energy balance: (1) adipocyte diameter in subcutaneous adipose tissue was smaller and decreased to a greater extent in Tibetan than in Small-tailed Han sheep, but the opposite occurred in the visceral adipose tissue; (2) Tibetan sheep showed higher insulin receptor mRNA expression and lower concentrations of catabolic hormones than Small-tailed Han sheep and (3) Tibetan sheep had lower capacity for glucose and fatty acid uptake than Small-tailed Han sheep. Moreover, Tibetan sheep had lower AMPKα mRNA expression but higher mammalian target of rapamycin mRNA expression in the adipocytes than Small-tailed Han sheep. We concluded that Tibetan sheep had lower catabolism but higher anabolism in adipose tissue and reduced the capacity for glucose and fatty acid uptake to a greater extent than Small-tailed Han sheep to maintain energy homoeostasis when in negative energy balance. These responses provide Tibetan sheep with a high ability to cope with low energy intake and with the harsh environment of the QTP.

Use of reduced-energy content maintenance diets for modest weight reduction in overweight cats and dogs.

One option for controlled weight loss for dogs and cats in overweight condition could be to modestly restrict caloric intake using a reduced-energy ('light') maintenance diet, but there is no prior research on the safety and efficacy of such an approach. A prospective observational cohort study was performed in 67 overweight dogs and 17 overweight cats undergoing weight loss using reduced-energy maintenance diets from one manufacturer. Diets were fed at approximately 80% of maintenance energy requirements for ideal bodyweight for a period of 8 weeks. Essential nutrient intake was estimated for each dog and cat and compared with minimum requirement (MR) or adequate intake (AI, when no MR had been demonstrated) as set by the National Research Council in 2006. Weight loss was seen in 56/67 dogs (84%), losing a median of 4.7% (range 15.2% loss to 10.0% gain) of their starting body weight (SBW). Weight loss was also seen in all 17 cats, losing a median of 6.4% (range 2.0 loss to 15.2% loss) of SBW. Of the essential nutrients examined, only selenium, choline, potassium, and riboflavin were less than NRC recommendations in a minority of animals. However, no signs of any nutrient deficiency were observed in any of the dogs or cats during the study. In summary, modestly energy restricting overweight dogs and cats when feeding a low-energy maintenance diet can induce weight loss and might be a useful initial step for weight management. Although no adverse effects were seen, borderline intake of some micronutrients warrants further consideration.

Cats reorganise their feeding behaviours when moving from ad libitum to restricted feeding.

OBJECTIVES: One identified solution to prevent obesity in cats is to control and limit their calorie intake. The objective of the present work was to better elucidate the impact of calorie cut-off on the feeding behaviour of cats. METHODS: A control (n = 31) and a test group of cats (n = 38) were included in the present study. Both groups received the same food variety during the study. A period of ad libitum feeding was initially set (T0), followed by a 9-month mild calorie restriction period for the test group only (T9; average calorie restriction = 6%), and a final period of ad libitum feeding (T10). The individual cat feeding behaviours were measured via an electronic feeding system, and agonistic interactions between cats during food anticipation via video observations. Generalised linear mixed models were fitted to compare all feeding parameters between periods by group. No statistical analyses could be performed on the agonistic interactions data owing to their structure. RESULTS: The feeding behaviour of the control group remained stable during the entire study, while the test group showed fewer but larger meals taken at shorter time intervals and a faster eating rate in response to calorie restriction. The average total number of agonistic interactions per cat increased during the calorie cut-off period in the test group only. One month after returning to ad libitum feeding, all behaviours were largely restored to baseline values. CONCLUSIONS AND RELEVANCE: Behavioural changes expressed by cats under calorie restriction can explain some of the difficulties obtaining cat owners' compliance with dietary restriction, especially in multi-cat households. Feeding strategies should be utilised to help cats be less impulsive and maintain normal feeding patterns when moving away from ad libitum feeding.

Factors associated with failure of dog's weight loss programmes.

BACKGROUND: Canine obesity is the cause of several health issues, and may predispose other diseases, such as orthopaedic disorders, endocrinopathies, metabolic abnormalities and cardiorespiratory disease which can lead to a decreased quality of life and reduced lifespan. Dog are considered overweight when their body weight is ≥15% above their ideal body weight, and as obese when their body weight exceeds 30% of optimal. Prevalence of canine obesity is estimated to be around 5%-20%, and up to 30%-40% when all overweight dogs are considered. Treatment is based on weight loss programmes, focused on caloric restriction associated with exercise. However, success rate of treatment is low. OBJECTIVES: The aim of this study was to investigate the reasons for weight loss failure of obese dogs during treatment with low-calorie diets. METHODS: Records of obese dogs undergoing weight loss programmes between May 2014 and May 2017, assessed by a team specialized in veterinary nutrition, were retrospectively evaluated. Dogs were classified according to weekly weight loss rate (WWLR) (<1%, between 1% and 2%, and more than 2%) and owner compliance with a dietary prescription and physical activity recommendations. RESULTS: The mean WWLR was not satisfactory (<1%) in 64.4% (n = 47/73) of dogs. Regarding owner compliance with the dietary prescription, 44.7% (n = 21/47) of owners did not follow diet prescriptions and physical activity recommendations for their dogs. There was a significant association (p = .01) between compliance of owners and satisfactory weight loss rate; however, there was no association between weight loss success, diet composition sex, reproductive status, age of the dogs and their physical activity (p ≥ .05). CONCLUSIONS: Non-compliance represents a great challenge in the treatment of canine obesity, and may be of more importance than other aspects.

Dairy cows fed a low energy diet before dry-off show signs of hunger despite ad libitum access.

Drying-off is one important management step in commercial dairy farms and consists of ceasing milk production artificially at a specific point in time, generally 2 months before the next calving. Drying-off typically comprises dietary changes as well as gradual or abrupt changes in daily milking frequency, which may challenge the welfare of high-yielding cows. This study investigated the isolated and combined effects of different feed energy densities (normal lactation diet versus energy-reduced diet, both offered ad libitum) and daily milking frequencies (twice versus once) on the feeding motivation of dairy cows on two separate days prior to dry-off (i.e. the day of last milking) using a push-gate feeder. During both days, cows on the energy-reduced diet pushed more than five times more weight to earn the final feed reward and were nearly ten times faster to feed on the first reward than cows on the normal lactation diet. Illustrating the importance of developing more animal welfare-friendly dry-off management, these results illustrate that cows show signs of hunger prior to dry-off when provided a diet with reduced energy density, although offered for ad libitum intake.

The Bone Marrow Protects and Optimizes Immunological Memory during Dietary Restriction.

Mammals evolved in the face of fluctuating food availability. How the immune system adapts to transient nutritional stress remains poorly understood. Here, we show that memory T cells collapsed in secondary lymphoid organs in the context of dietary restriction (DR) but dramatically accumulated within the bone marrow (BM), where they adopted a state associated with energy conservation. This response was coordinated by glucocorticoids and associated with a profound remodeling of the BM compartment, which included an increase in T cell homing factors, erythropoiesis, and adipogenesis. Adipocytes, as well as CXCR4-CXCL12 and S1P-S1P1R interactions, contributed to enhanced T cell accumulation in BM during DR. Memory T cell homing to BM during DR was associated with enhanced protection against infections and tumors. Together, this work uncovers a fundamental host strategy to sustain and optimize immunological memory during nutritional challenges that involved a temporal and spatial reorganization of the memory pool within "safe haven" compartments.

Feeding restriction alleviates high carbohydrate diet-induced oxidative stress and inflammation of Megalobrama amblycephala by activating the AMPK-SIRT1 pathway.

This study investigated the effects of restricted feeding on the growth performance, oxidative stress and inflammation of Megalobrama amblycephala fed high-carbohydrate (HC) diets. Fish (46.94 ±â€¯0.04 g) were randomly assigned to four groups containing the satiation of a control diet (30% carbohydrate) and three satiate levels (100% (HC1), 80% (HC2) and 60% (HC3)) of the HC diets (43% carbohydrate) for 8 weeks. Results showed that HC1 diet remarkably decreased final weight (FW), weight gain rate (WGR), specific growth rate (SGR), feed conversion ratio (FCR), hepatic activities of total anti-oxidation capacity (T-AOC), superoxide dismutase (SOD) and catalase (CAT), the AMP/ATP ratio, the p-AMPKα/t-AMPKα ratio, sirtuin-1 (SIRT1) protein expression and hepatic transcriptions of AMPKα2, SIRT1, nuclear factor erythroid 2-related factor 2 (Nrf2), catalase (CAT), manganese superoxide dismutase (Mn-SOD), glutathione peroxidase 1 (GPx1) and interleukin10 (IL 10) compared to the control group, whereas the opposite was true for protein efficiency ratio (PER), nitrogen retention efficiency (NRE), energy retention efficiency (ERE), plasma glucose levels, alanine transaminase (AST) and aspartate aminotransferase (ALT) activities, hepatic contents of malondialdehyde (MDA), tumour necrosis factor α (TNF α) and interleukin 1ß (IL 1ß), ATP and AMP contents and hepatic transcriptions of kelch-like ECH associating protein 1 (Keap1), IkB kinase α (IKK α), nuclear factor kappa B (NF-κB), TNF α, IL 1ß, interleukin 6 (IL 6) and transforming growth factor ß (TGF ß). As for the HC groups, fish fed the HC2 diet obtained relatively high values of SGR, PER, NRE, ERE, hepatic activities of T-AOC, SOD and CAT, the AMP/ATP ratio, the p-AMPKα/t-AMPKα ratio, SIRT1 protein expression and hepatic transcriptions of AMPKα2, Nrf2, CAT, copper/zinc superoxide dismutase (Cu/Zn-SOD), Mn-SOD, GPx1, glutathione S-transferase (GST) and interleukin10 (IL 10), while the opposite was true for hepatic content of IL 6 and transcription of IKK α. Overall, an 80% satiation improved the growth performance and alleviated the oxidative stress and inflammation of blunt snout bream fed HC diets via the activation of the AMPK-SIRT1 pathway and the up-regulation of the activities and transcriptions of Nrf2-modulated antioxidant enzymes coupled with the depression of the levels and transcriptions of the NF-κB-mediated pro-inflammatory cytokines.

Effects of l-arginine on endometrial estrogen receptor α/ß and progesterone receptor expression in nutrient-restricted sheep.

This study aimed to determine the effects of l-arginine (L-Arg) supplementation on steroid hormone receptors in non-pregnant ovine endometrium. All experimental ewes were randomly assigned to either a control group (n = 6), a nutrient-restricted group (n = 6), or an L-Arg supplemented nutrient-restricted group (n = 6). The effects of L-Arg on estrogen receptor α/ß (ERα/ß) and progesterone receptor (PGR) expression in the ovine endometrium were assessed. Our results showed that levels of ERß and PGR expression were significantly increased by nutrient restriction, but L-Arg counteracted the effect of nutrient restriction on ERß and PGR expression (p < 0.05). Also, expression of endometrial ERα was substantially increased (p < 0.05) by L-Arg supplementation. Furthermore, ERα/ß and PGR were mainly detected in the endometrial luminal epithelium and glandular epithelium. Therefore, we isolated and identified endometrial epithelial cells (EECs) from sheep. Different concentrations of L-Arg were added to investigate the effects on ERα/ß and PGR in EECs. The expression levels of endothelial nitric oxide synthase, ERß, and PGR were significantly increased in response to low-concentration (200 µmol) L-Arg supplementation, which subsequently decreased with a high concentration (800 µmol) (p < 0.05). Otherwise, ERα expression was remarkably increased at both L-Arg concentrations in EECs (p < 0.05). Overall, the results indicated that L-Arg performed crucial roles in the regulation of ovine steroid hormone receptor expression in the endometrium. The results of this study provide a theoretical basis and technical means for the normal function of endometrium in response to low nutrient levels.

An open-label randomised clinical trial to compare the efficacy of dietary caloric restriction and physical activity for weight loss in overweight pet dogs.

Canine obesity is usually managed with a combination of dietary caloric restriction and increasing physical activity, but no previous study has compared both of these strategies in a prospective randomised controlled trial. Thirteen overweight dogs (body condition score 6-9/9) were randomised to one of two interventions: dietary caloric restriction or physical activity. The dietary caloric restriction intervention comprised feeding a therapeutic weight loss diet, while the physical activity intervention comprised increasing the dog's current physical activity pattern by at least a third. The primary outcome measure was change in body weight, while secondary outcome measures included change in neck, thorax and abdominal circumference and change in physical activity measured by triaxial accelerometer. Bodyweight decreased significantly with the dietary caloric restriction (median -10% of starting body weight [SBW], 5 to -12%; P=0.028) but not with the physical activity intervention (-2% SBW, +3% to -6%; P=0.107). Abdominal circumference (dietary caloric restriction: median -12.0%; physical activity: median -7.8%, P=0.016) and thoracic circumference (dietary caloric restriction: median -7.5%, P=0.031; physical activity: median -3.6%, P=0.031) changed significantly in both groups. There was no change in activity levels within the dietary caloric restriction group, but vigorous activity increased significantly in the physical activity group (P=0.016). Dietary caloric restriction was more effective than physical activity for controlled weight loss in overweight pet dogs. Although advising owners to increase their dog's activity by a third led to a modest increase in measured vigorous physical activity, this was insufficient to promote weight loss on its own.

Effects of maternal feed intake restriction during pregnancy on the expression of growth regulation, imprinting and epigenetic transcription-related genes in foetal goats.

Maternal nutrition during gestation is a leading factor of modifying the foetal epigenome and phenotype for mammals. Imprinting genes have important roles in regulating foetal growth, programming and development. There, however, are limited data available on the effects of feed intake restriction on the expression of imprinting genes in pregnant goats. The present study, therefore, was conducted to assess the effects of maternal feed intake restriction on the relative abundance of mRNA for growth imprinting, DNA methyltransferase (DNMT) and epigenetic transcription-related genes in the liver and heart of foetal goats during gestation. A total of 24 Liuyang black goats (2.0±0.3 yr) with similar body weight (BW, 31.22±8.09 kg) and parity (2) were allocated equally to either a control group (CG) or a restriction group (RG) during both early (from 26 to 65 days) and late (from 96 to 135 days) gestation. All goats were fed a mixed diet and had free access to fresh water. The feed of the RG was 40% less than that of the CG. The early and late gestation goats were weighed, bled and slaughtered on days 65 and 135 of gestation, respectively. In early gestation, the foetal weight, body length, the weight of foetal heart and liver were greater (P < 0.05) in the RG. The CpG methylation of genomic DNA in the foetal heart was less (P = 0.0001) in the RG. The relative abundance of mRNA of methyl-CpG-binding domain protein 2 (MBD2) and methyl-CpG-binding domain protein 3 (MBD3) genes in the foetal liver were greater (P < 0.05) in the RG. During the late gestation, the foetal weight, heart weight and liver weight were less (P < 0.05) in the RG. The relative abundance of mRNA for the MBD2 gene (P = 0.043) in the foetal heart, and the ten-eleven translocation protein 1 (TET1) gene (P < 0.05) in both the foetal heart and liver were greater in the RG. These results indicate feed intake restriction during gestation influenced foetal development and regulated the relative abundance of mRNA for epigenetic transcription-related genes.

Risk of nutritional deficiencies for dogs on a weight loss plan.

OBJECTIVES: To determine how general practice veterinarians make weight loss recommendations for dogs and if nutrients become deficient when following these recommendations. MATERIALS AND METHODS: A questionnaire of general practice veterinarians was conducted to characterise weight loss recommendations made to clients. Using this data, progressive levels of caloric restriction were applied to top-selling commercial non-therapeutic adult maintenance diets and non-therapeutic weight management diets. Nutrient intakes were compared to the National Research Council's Recommended Allowances for metabolic body weight using a theoretical current weight and ideal body weight for an obese dog. Nutrient intakes were also compared to recommendations from the Association of American Feed Control Officials using current body weight. RESULTS: Several nutrients were found at risk of deficiency, including choline, methionine, cysteine, selenium, eicosapentanoic acid, docosahexanoic acid, riboflavin, pantothenic acid and cobalamin in both non-therapeutic adult maintenance diets and non-therapeutic weight management diets. CLINICAL SIGNIFICANCE: Caution is warranted when making weight loss recommendations using commercial diets until further research on the nutrient needs of obese dogs undergoing weight loss is undertaken. Restriction of commercial diets to achieve weight loss in dogs may result in nutrient deficiencies.

Weight loss improves arterial blood gases and respiratory parameters in obese dogs.

Canine obesity is a common medical disorder and a known risk factor for associated diseases; it can seriously influence various physiological functions, thereby limiting the longevity of the animal. In this study, we evaluated potential respiratory alterations in obese dogs before and after being subjected to caloric restriction to decrease their body weight by 20%, and compared those dogs with control dogs with ideal body condition score. The animals were divided into three experimental groups: GI (obese dogs; n = 11); GII (obese dogs after weight loss, same animals as in GI); GIII (control dogs; n = 11). We evaluated lung function by spirometry and arterial blood gases. Statistical analysis included paired or non-paired Student's t test. Compared with dogs within an ideal body condition score (GIII), obese dogs (GI) had a low arterial partial pressure of oxygen (p < 0.05); decreased tidal volume (p < 0.005), inspiratory time and expiratory time (p < 0.05); and an increased respiratory rate (p < 0.005). After losing weight (GII), no differences with control dogs (GIII) were verified. The results suggested that obese dogs have an improvement in respiratory function with weight loss, but further investigations in a larger group of dogs are advised to confirm these findings.

Longitudinal analysis of direct and indirect effects on average daily gain in rabbits using a structured antedependence model.

BACKGROUND: Indirect genetic effects (IGE) are important components of various traits in several species. Although the intensity of social interactions between partners likely vary over time, very few genetic studies have investigated how IGE vary over time for traits under selection in livestock species. To overcome this issue, our aim was: (1) to analyze longitudinal records of average daily gain (ADG) in rabbits subjected to a 5-week period of feed restriction using a structured antedependence (SAD) model that includes IGE and (2) to evaluate, by simulation, the response to selection when IGE are present and genetic evaluation is based on a SAD model that includes IGE or not. RESULTS: The direct genetic variance for ADG (g/d) increased from week 1 to 3 [from 8.03 to 13.47 (g/d)2] and then decreased [6.20 (g/d)2 at week 5], while the indirect genetic variance decreased from week 1 to 4 [from 0.43 to 0.22 (g/d)2]. The correlation between the direct genetic effects of different weeks was moderate to high (ranging from 0.46 to 0.86) and tended to decrease with time interval between measurements. The same trend was observed for IGE for weeks 2 to 5 (correlations ranging from 0.62 to 0.91). Estimates of the correlation between IGE of week 1 and IGE of the other weeks did not follow the same pattern and correlations were lower. Estimates of correlations between direct and indirect effects were negative at all times. After seven generations of simulated selection, the increase in ADG from selection on EBV from a SAD model that included IGE was higher (~ 30%) than when those effects were omitted. CONCLUSIONS: Indirect genetic effects are larger just after mixing animals at weaning than later in the fattening period, probably because of the establishment of social hierarchy that is generally observed at that time. Accounting for IGE in the selection criterion maximizes genetic progress.