Influence of a high ambient temperature on stearoyl-CoA-desaturase activity in the growing pig

Heat Production of Iberian Pig Exposed to High Temperature and Effect of Dietary Supplementation with Betaine or Zinc

The effect of heat, and dietary betaine or zinc on the heat production (HP) of Iberian pigs was studied. Thirty barrows (44 kg) were individually housed for 28 days and assigned to one of five treatments: (1) thermoneutrality (20 °C) and fed a control diet (TN-CON) ad libitum; (2) hot (30 °C) and fed a control diet (HT-CON) ad libitum; (3) thermoneutrality and pair fed a control diet (TN-CON-PF) to HT-CON; (4) hot and fed a betaine-supplemented (0.5%) diet (HT-BET) ad libitum; and (5) hot and fed a zinc-supplemented (0.012%) diet (HT-ZN) ad libitum. On the 18th day, pigs were moved to a respirometry chamber (two chambers) under their respective treatment. The metabolizable energy (ME) intake, HP and respiratory quotient (RQ) were measured over 24 h. No differences (p > 0.05) were found in HP and RE between treatments. For RQ, TN-CON was greater (p < 0.01) than HT treatments, except for HT-BET. All RQs indicated an overall lipogenesis where betaine supplementation showed an intermediate value, indicating that it may have a positive effect on lipogenesis and overall growth. At 30 °C, betaine or zinc had no effect on HP and RE; ME intake was not reduced, indicating a genetic adaptation of Iberian pigs to heat.

Alleviating Heat Stress in Fattening Pigs: Low-Intensity Showers in Critical Hours Alter Body External Temperature, Feeding Pattern, Carcass Composition, and Meat Quality Characteristics

Heat stress is a significant environmental problem that has a detrimental impact on animal welfare and production efficiency in swine farms. The current study was conducted to assess the effect of low-intensity showers, provided during critical high-temperature hours daily, on body external temperature, feeding pattern, and carcass and meat quality characteristics in fattening pigs. A total of 400 animals (200 barrows and 200 gilts) were randomly allotted in 40 pens. A shower nozzle was installed over 20 pens (half barrows and half gilts) where pigs received a low-intensity shower for 2 min in 30 min intervals from 12 to 19 h (SHO group). Another group without showers was also considered (CON). Feeder occupancy measurement, thermographic measures, and carcass and meat quality parameters were studied. In the periods with higher environmental temperatures, SHO animals showed an increase in the feeder occupancy rate compared to the CON group. A decrease in temperature was observed after the shower, regardless of the anatomical location (p < 0.005). The treatment with showers led to higher values than in the CON group of 4.72%, 3.87%, 11.8%, and 15.1% for hot carcass weight, lean meat yield, and fat thickness in Longissimus Dorsi (LD) and Gluteus Medius muscles, respectively (p < 0.01). Pork from CON showed a 14.9% higher value of drip loss, and 18.9% higher malondialdehyde concentration than SHO (p < 0.01); meanwhile, intramuscular fat content was 22.8% higher in SHO than in CON (p < 0.01). On the other hand, the CON group exhibited higher L* (2.13%) and lower a* and b* values (15.8% and 8.97%) compared to the SHO group. However, the pH20h of the CON group was significantly lower than that of the SHO group (p < 0.001), indicating a softer pH decrease. Related to fatty acids in subcutaneous outer and inner layers and intramuscular fat, the CON group showed higher ΣSFA and lower ΣMUFA and Δ9-desaturase indexes than SHO (p < 0.05). In conclusion, the amelioration of heat stress through showers at critical times should be considered an interesting tool that improves both carcass and meat quality, as well as animal welfare.

Maternal heat stress regulates the early fat deposition partly through modification of m6A RNA methylation in neonatal piglets

It is known that heat stress induces various physiological challenges in livestock production including changes in lipid metabolism. However, the molecular mechanism of how heat stress regulates lipid metabolism at the mRNA level is still largely unknown. N6-methyl-adenosine (m6A) is the most common and abundant modification on RNA molecules present in eukaryotes, which affects almost all aspects of RNA metabolism and thus gives us the hint that it may participate in changes of gene expression of lipid metabolism during heat stress. Therefore, the purpose of the present study was to investigate the effect of heat stress on fat metabolism in 21-day Large White × Landrace piglets from sows challenged by heat stress from day 85 of gestation until day 21 of lactation. We measured the expression of heat shock proteins (HSPs), genes associated with lipid metabolism, m6A-related enzymes, and m6A levels in abdominal fat and liver of offspring piglets. Our results showed that high ambient temperature significantly increased the expression of HSP70 (P < 0.01) in both liver and abdominal fat and upregulated HSP27 in the liver (P < 0.05). Additionally, genes involved in fat metabolism such as ACACA, FASN, DGAT1, PPAR-γ, SREBP-1c, and FABP4 were upregulated in abdominal fat in the experimental group challenged by high ambient temperature. In the liver, heat stress increased the mRNA expression of DGAT1, SREBP-1c, and CD36 and decreased ATGL and CPT1A expression (P < 0.05). The m6A level was higher in the heat stress group compared with the control group in the liver and abdominal fat of offspring piglets (P < 0.01). Notably, heat stress also increased gene expression of METTL14, WTAP, FTO, and YTHDF2 (P < 0.05) in both abdominal fat and liver. The protein abundances of METTL3, METTL14, and FTO were upregulated after heat stress in abdominal fat (P < 0.05) but not in the liver. Although there was no difference in the protein abundance of YTHDF2 in abdominal fat, its level was increased in the liver (P < 0.05). In conclusion, our findings showed that heat stress increased expression of genes involved in lipogenesis, which provided scientific evidence to the observation of increased fatness in pigs under heat stress. We also demonstrated a possible mechanism that m6A RNA modification may be associated with these changes in lipid metabolism upon heat stress.

Associations of Gut Microbiota With Heat Stress-Induced Changes of Growth, Fat Deposition, Intestinal Morphology, and Antioxidant Capacity in Ducks

Accumulating evidence has revealed the dysbiosis of gut/fecal microbiota induced by heat stress (HS) in mammals and poultry. However, the effects of HS on microbiota communities in different intestinal segments of Cherry-Valley ducks (a widely used meat-type breed) and their potential associations with growth performances, fat deposition, intestinal morphology, and antioxidant capacity have not been well evaluated yet. In this study, room temperature (RT) of 25°C was considered as control, and RT at 32°C for 8 h per day was set as the HS treatment. After 3 weeks, the intestinal contents of jejunum, ileum, and cecum were harvested to investigate the microbiota composition variations by 16S ribosomal RNA amplicon sequencing. And the weight gain, adipose indices, intestinal morphology, and a certain number of serum biochemical parameters were also measured and analyzed. The results showed the microbial species at different levels differentially enriched in duck jejunum and cecum under HS, while no significant data were observed in ileum. HS also caused the intestinal morphological changes (villus height and the ratio of villus height to crypt depth) and the reductions of growth speed (daily gain), levels of serum triglyceride (TG) and total cholesterol, and antioxidant activity (higher malondialdehyde (MDA) content and lower total antioxidant). The higher abdominal fat content and serum glucose level were also observed in HS ducks. The Spearman correlation analysis indicated that in jejunum the phyla Firmicutes and Proteobacteria were associated with average daily gain, feed/gain, serum TG and MDA levels, and villus height/crypt depth (P < 0.05). The phylum Firmicutes and genus Acinetobacter were significantly associated with fat deposition and serum glucose level (P < 0.05). The genus Lactobacillus was positively associated with serum total antioxidant (P < 0.05), while some other microbial species were found negatively associated, including order Pseudomonadales, genera Acinetobacter, and unidentified_Mitochondria. However, no significant correlations were observed in cecum. These findings imply the potential roles of duck gut microbiota in the intestinal injuries, fat deposition, and reductions of growth speed and antioxidant capacity caused by HS, although the molecular mechanisms requires further investigation.

Effects of heat stress and insulin sensitizers on pig adipose tissue

Heat stress (HS) negatively impacts several swine production variables, including carcass fat quality and quantity. Pigs reared in HS have more adipose tissue than energetically predicted, explainable, in part, by HS-induced hyperinsulinemia. Study objectives were to evaluate insulin's role in altering fat characteristics during HS via feeding insulin-sensitizing compounds. Forty crossbred barrows (113 ± 9 kg BW) were randomly assigned to one of five environment by diet treatments: 1) thermoneutral (TN) fed ad libitum (TNAL), 2) TN and pair-fed (TNPF), 3) HS fed ad libitum (HSAL), 4) HS fed ad libitum with sterculic oil (SO) supplementation (HSSO; 13 g/d), and 5) HS fed ad libitum with dietary chromium (Cr) supplementation (HSCr; 0.5 mg/d; Kemin Industries, Des Moines, IA). The study consisted of three experimental periods (P). During P0 (2 d), all pigs were exposed to TN conditions (23 ± 3 °C, 68 ± 10% RH) and fed ad libitum. During P1 (7 d), all pigs received their respective dietary supplements, were maintained in TN conditions, and fed ad libitum. During P2 (21 d), HSAL, HSSO, and HSCr pigs were fed ad libitum and exposed to cyclical HS conditions (28 to 33 °C, 58 ± 10% RH). The TNAL and TNPF pigs remained in TN conditions and were fed ad libitum or pair-fed to their HSAL counterparts. Rectal temperature (TR), respiration rate (RR), and skin temperature (TS) were obtained daily at 0600 and 1800 h. At 1800 h, HS exposed pigs had increased TR, RR, and TS relative to TNAL controls (1.13 °C, 48 bpm, and 3.51 °C, respectively; P < 0.01). During wk 2 and 3 of P2, HSSO pigs had increased 1800 h TR relative to HSAL and HSCr (~0.40 and ~0.42 °C, respectively; P ≤ 0.05). Heat stress decreased ADFI and ADG compared to TNAL pigs (2.24 vs. 3.28 and 0.63 vs. 1.09 kg/d, respectively; P < 0.01) and neither variable was affected by SO or Cr supplementation. Heat stress increased or tended to increase moisture content of abdominal (7.7 vs. 5.9%; P = 0.07) and inner s.c. (11.4 vs. 9.8%; P < 0.05) adipose depots compared to TNAL controls. Interestingly, TNPF pigs also had increased adipose tissue moisture content and this was most pronounced in the outer s.c. depot (15.0 vs. 12.2%; P < 0.01) compared to TNAL pigs. Heat stress had little or no effect on fatty acid composition of abdominal, inner, and outer s.c. adipose tissue depots. In summary, the negative effects of HS on fat quality do not appear to be fatty acid composition related, but may be explained by increased adipose tissue moisture content.

Heat stress in pigs is accompanied by adipose tissue-specific responses that favor increased triglyceride storage

Heat stress (HS) negatively affects all aspects of performance in pigs. Although certain tissue-specific responses in the liver, skeletal muscle, and intestine are known, there is paucity of information on responses within the adipose tissue. Therefore, the objective of this study was to delineate adipose tissue responses during HS in pigs. Thirty crossbred (Ossabaw × Duroc × Landrace) pigs were assigned to 3 treatments for 7 d. Treatments were 1) control and libitum fed (CON) with room temperature set at 20°C ± 1°C, 2) pair fed (PF) with room temperature as the CON treatment but pair fed to HS pigs, and 3) HS with room temperature 35°C ± 1°C and ad libitum access to feed. Compared with CON pigs, HS pigs had decreased feed intake and elevated skin temperature and respiration rate ( < 0.01). Blood urea nitrogen was higher ( = 0.01) in HS pigs compared with CON pigs only in males. In both subcutaneous and mesenteric adipose tissue, mRNA abundance of phosphoenolpyruvate carboxykinase (PCK1) was more elevated ( < 0.01) in HS groups compared with the CON and PF groups. Heat stress also caused increased heat shock protein 70 (HSP70; = 0.067) and CCAT/enhancer-binding homologous protein (CHOP) content ( < 0.05) in the mesenteric fat compared with the CON treatment. In conclusion, induction of PCK1 expression in adipose tissue by HS suggests elevated glyceroneogenesis might be involved in the increased fat storage in pigs under HS.

Effects of high ambient temperature on meat quality, serum hormone concentrations, and gene expression in the longissimus dorsi muscle of finishing pigs

This study examined the effect of high ambient temperature on the growth performance, meat quality, activity of the hypothalamo-pituitary-adrenal axis, and related gene expression in finishing pigs. All pigs received the same corn-soybean meal-based diet. Twenty-four Landrace pigs (initial bodyweight of 77.64 ± 0.67 kg) were assigned into three groups: Group 1 (22°C, ad libitum, 81% humidity); Group 2 (22°C, pair-fed to Group 3, 78% humidity); Group 3 (35°C, ad libitum, 78% humidity). The experiment lasted for 30 days. The average daily feed intake and average daily gain were markedly reduced in Group 3 compared with Group 1 (P < 0.05). The intramuscular fat content of longissimus dorsi muscle was decreased in Groups 2 and 3 (P < 0.05) when compared with Group 1. Muscle pH at 24 h post-mortem was higher in Group 3 (P < 0.05) compared with Groups 1 and 2, and the pH at 48 h post-mortem was higher in Group 3 (P < 0.05) than in Group 1. The MyHC IIb transcript abundance was lower in Group 3 (P < 0.05) than in the other two groups and that of MyHC IIx was higher in Group 3 than in Group 2 (P < 0.05). The relative abundance of calpastatin transcripts was lower in Group 3 (P < 0.05) than in the other two groups. Cortisol concentrations were lower in Group 3 (P < 0.05) than in Groups 1 and 2 on Day 3. Corticotropin releasing hormone concentrations in Group 3 were lower at Day 3 (P < 0.05) when compared with Group 2 and at Day 30 when compared with Groups 1 and 2. Glucagon concentrations were lower in Group 3 (P < 0.05) when compared with Groups 1 and 2 on Day 30. These results indicate that the decreased intramuscular fat content of pigs at high ambient temperature results from the reduction in feed intake. Independently of its effect on feed intake, high ambient temperature affected the meat quality of finishing pigs by increasing pH value probably due to the lower serum concentrations of corticotropin releasing hormone, and inducing a transition of muscle fibre types from IIb to IIx.

An assessment of the fatty acid composition of horse-meat available at the retail level in northern Spain

The objective of the present study was to assess the fatty acid composition of horse-meat available at the retail market in northern Spain. Horse steaks (Longissimus thoracis et lumborum muscle; n=82) were purchased from butcher-shops and large grocery stores throughout six northern regions of Spain in two different seasons. Fat content differed significantly among regions (1.12 to 2.77%). Samples with higher intramuscular fat content presented the highest percentages of total monounsaturated fatty acids and the lowest contents of dimethylacetal and polyunsaturated fatty acids (PUFA), while the opposite was found in the leanest samples. A high variability was observed in the muscle and subcutaneous n-3 PUFA content. Overall, total n-3 PUFA content ranged between 1.17% and 18.9% in muscle fat and between 1.52% and 27.9% in backfat. Interestingly, almost 5% of surveyed loins from horse carcasses (4 out of 82) contained over 300mg of linolenic acid per 100g of meat which could have been marketed as a "source" of n-3 FAs according to Commission Regulation (EU) No 116/2010.

Label-free Quantitative Analysis of Changes in Broiler Liver Proteins under Heat Stress using SWATH-MS Technology

High temperature is one of the key environmental stressors affecting broiler production efficiency and meat yield. Knowledge of broiler self-regulation mechanisms under heat stress is important for the modern scale of poultry breeding. In the present study, the SWATH strategy was employed to investigate the temporal response of the broiler liver to heat stress. A total of 4,271 proteins were identified and used to generate a reference library for SWATH analysis. During this analysis, 2,377 proteins were quantified, with a coefficient of variation ≤25% among technical and biological replicates. A total of 257 proteins showed differential expression between the control and heat stressed groups. Consistent results for 26 and 5 differential proteins were validated respectively by MRM and western blotting quantitative analyses. Bioinformatics analysis suggests that the up- and down-regulation of these proteins appear involved in the following three categories of cellular pathways and metabolisms: 1) inhibit the ERK signaling pathway; 2) affect broiler liver lipid and amino acid metabolism; 3) induce liver cell immune responses to adapt to the high temperatures and reduce mortality. The study reported here provides an insight into broiler self-regulation mechanisms and shed light on the improved broiler adaptability to high-temperature environments.

Seasonal variation in the concentrations of conjugated linoleic and trans fatty acids in milk fat from commercial dairy farms is associated with pasture and grazing management and supplementary feeding practices

A study of irrigated pasture-based dairy farms that used split calving (autumn and spring) was undertaken in northern Victoria, Australia, to examine associations between nutrition, time of year and season of calving on the concentrations of isomers of trans 18  :  1 fatty acids and conjugated linoleic acids (CLA) in milk fat. Factors associated with time of year explained most of the variation, with the highest concentrations observed in spring and summer when pasture intake by herds was high. However, there was substantial variation observed between herds and time of year. The mean total CLA concentration was 9.1 mg/g milk fatty acids (range 1.1–35.4 mg/g) with the cis,trans-9,11 accounting for ~84% of the total CLA. The mean total trans 18 : 1 concentration was 60.5 mg/g milk fatty acids (range 13.6–267 mg/g) with vaccenic acid (trans-11 18 : 1) accounting for ~53% of total trans 18 : 1 fatty acids. Total CLA and vaccenic acid were highest in August–September (southern hemisphere spring) (15.1 and 76.3 mg/g milk fat) and lowest in November–March (5.6 mg/g milk fat) and May–July (9.53 mg/g milk fat), respectively. There was no association between season of calving and milk CLA or trans 18 : 1 fatty acid concentrations. Trans-10 and -11 18 : 1 fatty acids and trans/trans-CLA were negatively correlated with milk fat concentrations. Management strategies designed to increase the concentration of CLA and trans 18 : 1 fatty acids in milk fat would not need to consider the effects of season of calving or stage of lactation, but should focus on pasture availability and quality.

Effect of chronic heat exposure on fat deposition and meat quality in two genetic types of chicken

The effects of chronic heat stress on growth, proportion of carcass and fat deposition, and meat quality were investigated in 2 genetic types of chickens. One hundred and eight 5-wk-old male chickens from a commercially fast-growing strain (Arbor Acres, AA) and a locally slow-growing species (Beijing You chicken, BJY) were kept in the following conditions: constant optimal ambient temperature at 21 degrees C and ad libitum feeding (21AL), constant high ambient temperature at 34 degrees C and ad libitum feeding (34AL), and constant optimal ambient temperature 21 degrees C and pair-fed to the 34AL chickens (21PF). The results showed that feed intakes were decreased by heat exposure in both type of chickens at 8 wk of age (P<0.001). At 34 degrees C, AA broilers exhibited greatly decreased weight gain (22.38 vs. 61.45 g/d for 21AL) and lower breast proportion compared with 21AL, while the relevant indices of BJY chickens were not affected in hot condition. Abdominal fat deposition of BJY chickens was enhanced by heat exposure (P<0.05). Fat deposition of AA broilers was decreased in heat-exposed and pair-fed chickens. Abdominal and intermuscular fat deposition in 34AL birds, however, were enhanced compared with 21PF birds (P<0.01). The L* values, drip loss, initial pH, and shear force of breast meat in BJY chickens were not affected by treatments. In AA birds, chronic heat stress increased L* values and drip loss compared with 21AL, but pH and shear force were not affected by treatments. The results from this study indicated that the impact of heat stress was breed dependent and that BJY chickens showed higher resistance to high ambient temperature, which could be related to their increased feed efficiency and deposition of abdominal fat under heat exposure.

A reduced protein diet induces stearoyl-CoA desaturase protein expression in pig muscle but not in subcutaneous adipose tissue: relationship with intramuscular lipid formation

A reduced protein diet (RPD) is known to increase the level of intramuscular lipid in pig meat with a smaller effect on the amount of subcutaneous adipose tissue. This might be due to tissue-specific activation of the expression of lipogenic enzymes by the RPD. The present study investigated the effect of a RPD, containing palm kernel oil, soyabean oil or palm oil on the activity and expression of one of the major lipogenic enzymes, stearoyl-CoA desaturase (SCD) and on the level of total lipids and the fatty acid composition of muscle and subcutaneous adipose tissue in pigs. The RPD significantly increased SCD protein expression and activity in muscle but not in subcutaneous adipose tissue. The level of MUFA and total fatty acids in muscle was also elevated when the RPD was fed, with only small changes in subcutaneous adipose tissue. A positive significant correlation between SCD protein expression and total fatty acids in muscle was found. The results suggest that an increase in intramuscular but not subcutaneous adipose tissue fatty acids under the influence of a RPD is related to tissue-specific activation of SCD expression. It is suggested that the SCD isoform spectra in pig subcutaneous adipose tissue and muscle might be different.

Deposition of dietary fatty acids and ofde novosynthesised fatty acids in growing pigs: effects of high ambient temperature and feeding restriction

Predicting aspects of pork quality becomes increasingly important from both a nutritional and a technological point of view. Little information is, however, available concerning the quantitative relation between nutrient intake and fatty acid (FA) deposition at the whole-animal level. In this study, eight blocks of five littermate barrows were used in a comparative slaughter trial. At 24 kg body weight (BW), one pig from each litter was slaughtered to determine the initial FA composition. The other littermates were assigned to one of four feeding levels (ranging from 70 % to 100 % of intakead libitum) and were given a diet containing 0·36 g/kg lipid and 0·22 g/kg FA. The temperature for each block was maintained at either 23 or 30°C. At 65 kg, the pigs were slaughtered and the body lipid and FA composition was determined. Seventy per cent of the digestedn-6 FA and 50 % of then-3 FA were deposited. The average composition ofde novosynthesised FA corresponded to 1·7, 30·3, 2·4, 19·7 and 45·9 % for 14: , 16: , 16: 1, 18: and 18: 1 FA, respectively. At 23°C and for feedingad libitum, 33 % of 16: FA was deposited, 1·7 % shortened to 14: , 63 % elongated to 18: and 2·8 % unsaturated to 16: 1. Twenty-eight per cent of 18: FA was deposited and 72 % unsaturated to 18: 1. At 30°C, 18: FA desaturation was reduced by 3·5 %. Feed intake and temperature independently affected the elongation of 16: FA. A reduction in feed intake increased the elongation rate, whereas the increase in temperature reduced the elongation rate.

Effect of a high-linolenic acid diet on lipogenic enzyme activities, fatty acid composition, and meat quality in the growing pig

Forty-eight Duroc-cross gilts (40 kg initial BW) were fed a control or a linseed diet containing 60 g of whole crushed linseed/kg. Both diets were supplemented with 150 mg of vitamin E/kg. Eight pigs from each dietary treatment were slaughtered at 20, 60, or 100 d after the start of the experiment. There was no effect (P > 0.05) of diet on growth, carcass characteristics, or foreloin tissue composition. Feeding the linseed diet increased (P < 0.05) the content of n-3 PUFA in plasma, muscle, and adipose tissue, but docosahexaenoic acid was not (P > 0.05) altered by diet. The proportions of n-3 PUFA were highest (P < 0.01) in pigs fed the linseed-diet for 60 d, regardless of tissue (plasma, muscle, or adipose tissue) or lipid (neutral lipids and phospholipids) class. The linseed diet produced a PUFA:saturated fatty acid ratio > or = 0.4 in all groups and tissues, which is close to the recommended value for the entire diet of humans, as well as a robust decrease in the n-6:n-3 ratio. The decrease (P < 0.01) in the percentage of oleic acid in adipose tissue of pigs fed the linseed diet for 60 d could be attributed to a 40% decrease (P < 0.001) in stearoyl-CoA-desaturase activity. Diet did not (P > 0.05) affect the activities of acetyl-CoA-carboxylase, malic enzyme, or glucose-6-phosphate-dehydrogenase in any tissues. Muscle vitamin E content was decreased (P < 0.001) 30% in pigs fed crushed linseed for 60 d, whereas lower (P < 0.001) concentrations of skatole in pork fat were observed in linseed-fed pigs at all slaughter times. Inclusion of linseed (flaxseed) in swine diets is a valid method of improving the nutritional value of pork without deleteriously affecting organoleptic characteristics, oxidation, or color stability.