Combination of carbohydrases and essential oils improve dietary performance of feedlot steers on a high-energy diet

Essential oils and enzymes are alternatives to feed additives for ruminants that aim to replace the use of ionophores and improve animal performance, but their mechanisms of action are different. Therefore, the present study aimed to verify if there is a synergistic effect in the combined use of enzymes carbohydrates and essential oils on the performance, ingestive behavior and carcass traits of steers fed a high-energy diet. During the finishing period of 78 days, 40 steers were assigned to four treatments: CON- control; ENZ- enzymatic complex; EO- essential oil blend; ENZ+EO - enzymatic complex combined with essential oil blend. Regardless of the feedlot periods, the ENZ+EO treatment caused a reduction in the dry matter intake (12.48%) compared to the control. The ENZ+EO treatment resulted in the lowest mean fecal output and, consequently, the highest dry matter digestibility (DMD) and starch digestibility (SD), compared to the other treatments. Animals that received EO and ENZ+EO in the diet spent more time in feeding. As for the number of times animals visited the feeding trough, the highest values were presented by the animals in the EO, ENZ and ENZ+EO treatments. For the carcass parameters, only the subcutaneous fat thickness on the rib was significantly different between treatments, with the highest values obtained by adding EO and ENZ+EO (8.80 and 8.10 mm respectively). Thus, the combination of carbohydrate enzymes and essential oils proved to be synergistically beneficial in relation to better use of nutrients and productive performance of feedlot steers.

Effect of Post-grazing Sward Height on Ingestive Behavior, Dry Matter Intake, and Milk Production of Holstein Dairy Cows

Sward height is strongly related to the daily dry matter intake of grazing dairy cows, which consequently determines animal performance. Despite that, few studies have explored the potential to increase milk production by managing post-grazing sward height. An experiment was carried out to evaluate the effect of three defoliation intensities on a Lolium arundinaceum-based pasture on frequency and length of grazing meals and ruminating bouts, daily grazing and ruminating time, feeding stations and patches exploration, and dry matter intake and milk production of dairy cows. The treatments imposed were three different post-grazing sward heights: control (TC), medium (TM), and lax (TL), which were managed with 6, 9, and 12 cm of post-grazing sward heights during autumn and winter, and 9, 12, and 15 cm of post-grazing sward heights during spring, respectively. Thirty-six autumn-calving Holstein cows were grouped by parity (2.6 ± 0.8), body weight (618 ± 48) kg, and body condition score (2.8 ± 0.2) and randomized to the treatments. The pasture was accessed from 08:00 to 14:00 and 17:00 to 03:00 during spring and no supplement was involved during the evaluation period. Daily grazing time averaged 508 ± 15 min and was not affected by treatment. The reduction of post-grazing sward height increased the length of the first grazing session in the morning and the afternoon. The number of grazing sessions was greater on TL than on TM, with no difference in TC. The number of feeding stations (the hypothetical semi-circle in front of an animal from which the bites were taken without moving the front forefeet) visited was less on TC than on TL, and neither of them differed from TM. Dry matter (DM) intake was lesser on TC than on TM and TL (14.7 vs. 17.8 kg DM). Milk production during the evaluation period was 13.1, 16.2, and 18.7 kg/day for TC, TM, and TL, respectively. The milk fat, protein, and lactose content did not differ between treatments. The cows on TC exhibited a lower intake rate, although they were less selective, probably as a consequence of the sward structure of TC treatment. The cows on TM adopted a compensation mechanism which allowed them to achieve the same dry matter intake as cows on TL, but lower milk production. The cows on TL were more selective than TC and TM resulting in higher digestible dry matter intake and consequently higher milk production. The intensity of defoliation impacts on the animal-plant interaction, and constitutes a valuable management tool that can be used to boost forage intake and milk production. The new developments on information technology would allow researchers to link behavioral data with response variables (e.g., milk production, health, welfare, etc.) at different spatio-temporal scales and support short and long-term management decisions.

Which non-fibrous carbohydrates: neutral detergent fiber ratio optimizes the use of cactus cladodes in diets of growing heifers?

This study aimed to evaluate the effect of different non-fibrous carbohydrate (NFC):neutral detergent fiber (NDF) ratios (0.70:1, 0.90:1, 1.14:1, 1.42:1, and 1.85:1) in diets containing cactus cladodes on intake, digestibility, ruminal parameters, ingestive behavior, and microbial protein of growing heifers. Five rumen-cannulated heifers (194 ± 70 kg of body weight) were distributed in a Latin square design (5 x 5). There was a quadratic effect on the intake of dry matter (DM) (Kg day-1 and %BW) and crude protein (CP) with the increase in non-fibrous carbohydrate (NFC): neutral detergent fiber (NDF) ratio, with maximum values of 7.07 kg day-1, 2.86%, and 0.949 kg day-1, estimated for 1.37:1, 1.39:1, and 1.27:1 ratios. When the intake of NDF decreased, in turn, the intakes of NFC and TDN increased. The NDF digestibility decreased with increasing NFC levels in diets. The other nutrients were not influenced. The ruminal pH showed the lowest values at 4 hours after feeding, mainly for animals fed the 1.85:1 ratio. There was a quadratic effect for rumination time with maximum values estimated for an NFC:NDF ratio of 0.88:1. The time spent idle increased linearly, while total chewing time and feeding efficiency of NDF decreased. The urinary volume increased linearly. However, microbial protein synthesis and the efficiency of the synthesis were not influenced. The number of protozoa increased by 64.5% with the elevation of the NFC:NDF ratio. We recommend a NFC:NDF ratio of 1.37:1 in diets containing cactus cladodes, to improve the use of nutrients, without negatively affecting ruminal parameters.

Impaired trigeminal control of ingestive behavior in the Prrxl1- / - mouse is associated with a lemniscal-biased orosensory deafferentation

Although peripheral deafferentation studies have demonstrated a critical role for trigeminal afference in modulating the orosensorimotor control of eating and drinking, the central trigeminal pathways mediating that control, as well as the timescale of control, remain to be elucidated. In rodents, three ascending somatosensory pathways process and relay orofacial mechanosensory input: the lemniscal, paralemniscal, and extralemniscal. Two of these pathways (the lemniscal and extralemniscal) exhibit highly structured topographic representations of the orofacial sensory surface, as exemplified by the one-to-one somatotopic mapping between vibrissae on the animals’ face and barrelettes in brainstem, barreloids in thalamus, and barrels in cortex. Here we use the Prrxl1 knockout mouse model to investigate ingestive behavior deficits associated with disruption of the lemniscal pathway. The Prrxl1 deletion disrupts somatotopic patterning and axonal projections throughout the lemniscal pathway but spares patterning in the extralemniscal nucleus. Our data reveal an imprecise and inefficient ingestive phenotype with deficits that span timescales from milliseconds to months, tightly linking trigeminal input with ingestion, from moment-to-moment consummatory to long term appetitive control. We suggest that ordered assembly of trigeminal sensory information along the lemniscal pathway is critical for the rapid and precise modulation of motor circuits driving eating and drinking action sequences.

GABA and IA Independently Regulate rNST Responses to Afferent Input

Taste responses in the rostral nucleus of the solitary tract (rNST) influence motivated ingestive behavior via ascending pathways, and consummatory reflex behavior via local, brainstem connections. Modifications to the afferent signal within the rNST include changes in gain (the overall rate of neuron activity) and changes in gustatory tuning (the degree to which individual neurons respond to divergent gustatory qualities). These alterations of the sensory signal derive from both synaptic interactions within the nucleus and the constitutive cellular membrane properties of rNST neurons. GABA neurons are well represented within the rNST, as is expression of KV4.3, a channel for a rapidly inactivating outward K+ current (IA). GABAergic synapses suppress rNST responses to afferent input and previous studies showed that this suppression is greater in cells expressing IA, suggesting a possible interaction. Here, we examine the potential interaction between GABAergic inhibition and IA channels in a series of patch clamp experiments. Optogenetic release of GABA suppressed rNST responses to afferent (electrical) stimulation and this effect was greater in cells with IA, confirming an earlier report. We further observed that the composite inhibitory postsynaptic potential was larger in IA positive cells, suggesting one mechanism for the greater afferent suppression. Blocking IA with the channel blocker AmmTX3, enhanced the response to afferent stimulation, suggesting a suppressive role for this channel in regulating afferent input at rest. However, pharmacologic blockade of IA did not suppress GABAergic inhibition, indicating that IA and GABA independently regulate excitatory afferent input.

Does Rotational Grazing Based on Leaf Expansion Duration Modify Grazing Behavior and Feed Intake of Beef Heifers on Natural Grassland?

Grasslands develop a multifunctional role to humanity, with unique fauna and flora, besides being the primary feed source for herbivores. However, grasslands are usually considered a low-efficiency production system, often converted into other land uses such as crops and forestation (e.g., south Brazil). This study aimed to evaluate the effect of two rest intervals between grazing occupations in rotational grazing on the grazing behavior and feed intake of beef heifers. Two grazing intervals, 375 and 750 DD (degree-days) were used; based on the cumulative thermal sum necessary for the leaf expansion of native grasses of two functional groups. The experiment was conducted as a completely randomized block design, with two treatments, three replications, and repeated measures over time. The grazing behavior was evaluated continuously for 18 hours (7 a.m. to 11h59 p.m.). Herbage intake was estimated using an external marker (Cr2O3) in four periods (one for each season). The green leaf mass was similar between treatments, with a mean of 40% of the pregrazing mass (kg DM ha-1). On average grazing, time was 50% of the period, and the bite rate was 38.7 bites min-1. The number of daily meals was 6.5, with an average of 84 minutes for each meal. The number of feeding times (feeding stations by minute) visited was 6.4. On average, there was a 2.23% difference in dry matter intake (% BW) among seasons. Neither ingestive behavior or forage consumption of heifers was affected by the treatments, both maintain similar chemical composition on natural grassland.

Ensilajes de triticale de alta humedad con aditivos químicos y biológicos: valores nutrimentales y comportamiento de ingesta en ovinos

Triticale high moisture grain triticale silage is an excellent option for ruminant diets, but loss control during its fermentation process should be further investigated. Thus, the objective of this study was to evaluate the effects of chemical and biological additives on high moisture triticale silages under chemical-bromatological composition, aerobic stability, and in vivo digestibility and ingestive behavior in sheep. The treatments were: high moisture triticale silage without additive (HMTC); high moisture triticale silage with enzyme-bacterial inoculant (HMTEB); high moisture triticale silage with 0.5 % urea in natural matter (HMTU); and high moisture triticale silage with 1.5 % sodium benzoate in natural matter (HMTSB). Four sheep were housed in appropriate metabolic cages according to the ethical principles of animal experimentation. The addition of urea as additive to high moisture triticale silage provided an increase in crude protein and ammoniacal silage (189.7 and 106.2 g kg MS-1, respectively) but did not affect digestibility (699.6 g kg MS-1 for HMTU, with a general average of treatments of 687.5 g kg MS-1) and ingestive behavior of sheep. Fiber consumption by sheep increased with the addition of the enzyme-bacterial additive in the silage (431.87 versus 388.06 g d-1 of FDN for HMTEB and HMTC, respectively). All additives helped to preserve crude protein contents after silo opening, but none interfered in aerobic stability time of silage.

Apparent Digestibility and Ingestive Behavior of Nellore Bulls With Low and High Residual Feed Intake

The objective of this study was to determine the correlation between ingestive behaviour, apparent digestibility and residual feed intake (RFI) of finishing Nellore bulls fed a high concentrate diet. One hundred and twenty Nellore bulls, housed in individual pens, were evaluated in individual performance tests. The animals were fed a high concentrate diet (23:77roughage/concentrate ratio). The animals were classified as: low RFI, medium RFI, and high RFI. Data from ten animals from each group was used. Faecal production and nutrient digestibility were calculated using indigestible neutral detergent fiber as an internal marker. The feeding behaviour was evaluated over twenty-four hours by direct observation every five minutes. The most efficient animals (low RFI, 8.58 kg DM/day) consumed 27.62% less feed than the least efficient animals (high RFI, 10.95 kg DM/day). Animals with medium efficiency (mean RFI, 9.49 kg DM/day) consumed 15.39% less than high RFI. Nutrient digestibility coefficients were similar except for ether extract (P<0.03) which was 8% greater for the high-RFI animals. No effect was observed for ingestive behaviour (P>0.05). Animals spent, on average, three hours twenty-eight minutes feeding, seven hours thirty-two minutes ruminating and thirteen hours forty minutes in idle time. In the present study, ingestive behaviour and dry matter digestibility were not responsible for between-animal variation in residual feed intake in Nellore bulls fed a high concentrate diet.

Microbiota’s Role in Diet-Driven Alterations in Food Intake: Satiety, Energy Balance, and Reward

The gut microbiota plays a key role in modulating host physiology and behavior, particularly feeding behavior and energy homeostasis. There is accumulating evidence demonstrating a role for gut microbiota in the etiology of obesity. In human and rodent studies, obesity and high-energy feeding are most consistently found to be associated with decreased bacterial diversity, changes in main phyla relative abundances and increased presence of pro-inflammatory products. Diet-associated alterations in microbiome composition are linked with weight gain, adiposity, and changes in ingestive behavior. There are multiple pathways through which the microbiome influences food intake. This review discusses these pathways, including peripheral mechanisms such as the regulation of gut satiety peptide release and alterations in leptin and cholecystokinin signaling along the vagus nerve, as well as central mechanisms, such as the modulation of hypothalamic neuroinflammation and alterations in reward signaling. Most research currently focuses on determining the role of the microbiome in the development of obesity and using microbiome manipulation to prevent diet-induced increase in food intake. More studies are necessary to determine whether microbiome manipulation after prolonged energy-dense diet exposure and obesity can reduce intake and promote meaningful weight loss.