Raw diets for dogs and cats: Potential health benefits and threats.

Raw meat-based diets for pet nutrition are becoming increasingly popular. The percentage of meat content, composition of nutrients, and amount of additives started to play an important role in the recipe of a given food. However, the use of healthier and unprocessed food must also be balanced with the animal's specific needs based on its anatomy, physiology, and behavior. There are many potential advantages and disadvantages of a biologically appropriate raw food (BARF) diet, and all of them should be considered before switching to this approach. Raw meat is considered a diet closest to nature and least processed. However, raw diets threaten pet health because of the potential for nutrient imbalances. The choice of raw meat in pets' everyday diet should be supported by the veterinarian's medical decision and preferably also with nutritionist help. Growing animals require a specific Ca:P ratio in their diet, which may be improper in raw meat. For cats, taurine levels must be carefully checked. In addition, an imbalanced raw-meat diet can be the cause of poor semen quality in males. Females are prone to inhibition of the estrus cycle, especially due to hyperthyroidism. Exogenous thyroid hormone intake is a real concern when feeding a neck/head meat with thyroid glands. There is also a possibility of bacterial or parasitic presence in raw meat. The present paper aims to summarize the current state of knowledge about the benefits and threats of eating a raw meat diet for the health concerns of companion animals.

Review: Methanogens and methane production in the digestive systems of nonruminant farm animals.

The greenhouse gases (GHGs) derived from agriculture include carbon dioxide, nitrous oxide, and methane (CH4). Of these GHGs, CH4, in particular, constitutes a major component of the GHG emitted by the agricultural sector. Along with environmental concerns, CH4 emission also leads to losses in gross energy intake with economic implications. While ruminants are considered the main source of CH4 from agriculture, nonruminant animals also contribute substantially, and the CH4 emission intensity of nonruminants remains comparable to that of ruminants. Means of mitigating CH4 emissions from enteric fermentation have therefore been sought. Methane is produced by methanogens-archaeal microorganisms that inhabit the digestive tracts of animals and participate in fermentation processes. As the diversity of methanogen communities is thought to be responsible for the differences in CH4 production among nonruminant animals, it is necessary to investigate the archaeal composition of specific animal species. Methanogens play an important role in energy metabolism and adipose tissue deposition in animals. Higher abundances of methanogens, along with their higher diversity, have been reported to contribute to lean phenotype in pigs. In particular, a greater abundance of Methanosphaera spp. and early dominance of Methanobrevibacter smithii have been reported to correlate with lower body fat formation in pigs. Besides the contribution of methanogens to the metabolic phenotype of their hosts, CH4 release reduces the productivity that could be achieved through other hydrogen (H2) disposal pathways. Enhanced participation of acetogenesis in H2 disposal, leading to acetate formation, could be a more favorable direction for animal production and the environment. Better knowledge and understanding of the archaeal communities of the gastrointestinal tract (GIT), including their metabolism and interactions with other microorganisms, would thus allow the development of new strategies for inhibiting methanogens and shifting toward acetogenesis. There are a variety of approaches to inhibiting methanogens and mitigating methanogenesis in ruminants, which can find an application for nonruminants, such as nutritional changes through supplementation with biologically active compounds and management changes. We summarize the available reports and provide a comprehensive review of methanogens living in the GIT of various nonruminants, such as swine, horses, donkeys, rabbits, and poultry. This review will help in a better understanding of the populations and diversity of methanogens and the implications of their presence in nonruminant animals.

Technical note: Interchangeability and comparison of methane measurements in dairy cows with 2 noninvasive infrared systems.

This study aimed to compare measurements of methane (CH4) and carbon dioxide (CO2) concentrations in the breath of dairy cows kept in commercial conditions using the Fourier-transform infrared spectroscopy (FTIR) and nondispersive infrared spectroscopy (NDIR) methods. The measurement systems were installed in an automated milking system. Measurements were carried out for 5 d using both systems during milkings. The measurements were averaged per milking, giving 467 observations of CH4 and CO2 concentrations of 44 Holstein Friesian cows. The Pearson correlation between observations from the 2 systems was 0.86 for CH4, 0.84 for CO2, and 0.88 for their ratio. The repeatability of FTIR (0.53 for CH4, 0.57 for CO2, and 0.28 for their ratio) was somewhat higher than that of NDIR (0.57 for CH4, 0.47 for CO2, and 0.25 for their ratio). The coefficient of individual agreement was 0.98 for CH4, 0.89 for CO2, and 0.89 for their ratio; the concordance correlation coefficient was 0.48 for both gases and 0.24 for their ratio. We showed that FTIR and NDIR give similar results in commercial farm conditions. They can therefore be used interchangeably to generate a larger data set, which could then be further used for genetic evaluation.

Short communication: A nanoemulsified form of oil blends positively affects the fatty acid proportion in ruminal batch cultures.

Two consecutive rumen batch cultures were used to study the effect of nanoemulsified oils as a new type of supplement, on the in vitro fatty acid proportion and vaccenic acid formation. Three levels (3, 5, and 7%) of 2 different oil blends [soybean:fish oil (SF) or rapeseed-fish oil (RF)] were used. Both oil blends were used either in the raw form (SF or RF, respectively) or in the nanoemulsified form (NSF or NRF, respectively). The diets were the control (0%), which consisted of a dry total mixed ration without any supplements, the control plus 3, 5, or 7% of the SF or RF oil blend in appropriate form (raw or nanoemulsified). For each treatment, 6 incubation vessels were used. Each batch culture was incubated for 24h and conducted twice in 2 consecutive days. All supplements were calculated as a percentage of the substrate dry matter (400mg). Nanoemulsified supplements were recalculated to make sure the oil amount was equal to the raw oil supplementation levels. The results from both experiments indicated that the proportions of vaccenic acid and cis-9,trans-11 C18:2 increased when a raw oil blend was supplemented; on the other hand, no influence of nanoemulsified form of oil blend was observed on the proportion cis-9,trans-11 C18:2. Generally, supplementation with the nanoemulsified oil blends had less effect on biohydrogenation intermediates than the raw form of oil blends. However, the nanoemulsified form had a greater effect on the increase of n-3 and n-6 fatty acids. Nanoemulsified oil blends had a positive effect on decreasing the transformation rate of polyunsaturated fatty acids to saturated fatty acids in the biohydrogenation environment. Supplements of nanoemulsified oil blends tended to be more effective than supplements of raw oils in preserving a greater proportion of polyunsaturated fatty acids in the fermentation culture.

The metabolic profile of growing lambs fed diets rich in unsaturated fatty acids.

The effect of two diets enriched with unsaturated fatty acids--one containing the addition of dried distillers grains with solubles (DGS) and the other the addition of false flax--Camelina sativa cake (CS)--on some metabolic parameters and hormone concentration in growing lambs was determined in this experiment. A total of 21 ram lambs of the Polish Whiteheaded mutton sheep were divided into three groups (the control, receiving DGS and CS). The diets were administered to animals for 6 weeks. During the experiment, peripheral blood was collected. Glucose (GL), total cholesterol (CH), triglycerides (TG), free fatty acids (FFA), insulin (IN), leptin (LE), triiodothyronine (T3) and thyroxine (T4) were assayed in serum. The age-dependent reduction in CH and TG limited by both experimental diets were observed. A significant increase in FFA concentration was observed in samples collected in the last, that is, third, time period. This was most probably caused by a 12-h pre-slaughter fasting period. A significantly lower dynamic of FFA increase in that experimental period was found in animals receiving the experimental feed. Insulin concentration in DGS-receiving lambs was increased, in contrast to the CS-receiving lambs, in which it was lower when compared to the control. LE concentration was decreased by both experimental diets, more markedly in the DGS-receiving animals. No differences between the experimental groups and the control were observed in T3 and T4 concentrations. The effect of 12-h pre-slaughter fasting was statistically highly significant for the levels of examined blood markers and hormones, except for TG and IN in the group of lambs receiving the experimental diet with CS.

Plant components with specific activities against rumen methanogens.

A wide range of plant bioactive components (phytochemicals) have been identified as having potential to modulate the processes of fermentation in the rumen. The use of plants or plant extracts as natural feed additives has become a subject of interest not only among nutritionists but also other scientists. Although a large number of phytochemicals (e.g. saponins, tannins and essential oils) have recently been investigated for their methane reduction potential, there have not yet been major breakthroughs that could be applied in practice. A key tenet of this paper is the need for studies on the influence of plant components on methane production to be performed with standardized samples. Where there are consistent effects, the literature suggests that saponins mitigate methanogenesis mainly by reducing the number of protozoa, condensed tannins both by reducing the number of protozoa and by a direct toxic effect on methanogens, whereas essential oils act mostly by a direct toxic effect on methanogens. However, because the rumen is a complex ecosystem, analysis of the influence of plant components on the populations of methanogens should take into account not only the total population of methanogens but also individual orders or species. Although a number of plants and plant extracts have shown potential in studies in vitro, these effects must be confirmed in vivo.

No single way to explain cytoplasmic maturation of oocytes from prepubertal and cyclic gilts.

The objective of this study was to evaluate selected aspects of cytoplasmic maturation in oocytes from prepubertal and cyclic crossbred gilts before and after in vitro maturation. For this purpose, cortical granule redistribution, mitochondrial DNA content and mitochondria translocation were analyzed. Moreover, for the first time the fatty acid profiles in follicular fluid (FF) of both gilt categories was evaluated. The nuclear maturation (the percentage of metaphase II oocytes was 83% in prepubertal gilts compared with 87% in cyclic gilts), cortical granule relocation from the cortex to peripheral ooplasm (98.7% vs. 98.8% of oocytes, respectively) and mitochondrial DNA content (227 543 vs. 206 660, respectively) was not affected by sexual maturity of the donor gilt. However, the redistribution of active mitochondria during in vitro maturation was observed only in the oocytes of cyclic gilts. With regard to FF analysis, saturated, unsaturated, and monounsaturated fatty acids were significantly more abundant in the FF of prepubertal females. In particular, stearic (C18:0) and palmitic (C16:0) fatty acids had significantly higher concentrations in the FF of prepubertal gilts. In conclusion, although the oocytes of prepubertal gilts matured in vitro at a rate similar to those of cyclic gilts, they differed with respect to the selected factors attributed to cytoplasmic maturation. We suggest that the higher content of particular fatty acids, which is known to have a negative influence on oocyte maturation, as well as impaired mitochondria redistribution are factors limiting the maturation potential of oocytes from prepubertal gilts.