Distinct patterns of feed intake and their association with growth performance in broilers.

Improving feed utilization is a vital strategy to meet the growing global demand for meat and promote sustainable food production. Over the past few decades, significant improvements in the feed intake (FI) and feed utilization efficiency of broilers have been achieved through advanced breeding procedures, although dynamic changes in FI and their effects on the feed conversion ratio (FCR) have remained unclear. In this study, we measured individual weekly FI and body weight of 274 male broilers to characterize the dynamic FI patterns and investigate their relationship with growth performance. The broilers were from 2 purebred lines and their crossbreed and measurements were collected from 4 to 6 wk of age. Overall, a continuous increase in the weekly FI occurred from 4 to 6 wk of age, whereas the body weight gain (BWG) reached an inflection point in wk 5. The dynamic change in weekly FI was observed to follow 3 distinct FI patterns: pattern 1, a continuous weekly increase in FI; pattern 2, an increase followed by a plateau; pattern 3, an increase followed by a decrease. The prevalence of these patterns was similar in the purebred and crossbred populations: pattern 2 was most frequent, followed by a moderate proportion of pattern 1, and the lowest proportion of pattern 3. Broilers following pattern 1 displayed significantly better growth performance and feed utilization efficiency than those following pattern 3, emphasizing the importance of maintaining good appetite in the last stage of broiler production. In summary, this study has characterized the dynamic patterns of FI and their association with growth performance. Our results offer a new foundation for improving feed utilization efficiency and investigating feeding regulation in broilers.

Modeling the effect of ambient temperature on reticulorumen temperature, and drinking and eating behaviors of late-lactation dairy cows during colder seasons.

Dairy cows may suffer thermal stress during the colder seasons especially due to their open-air housing systems. Free water temperature (FWT) and feed temperature (FT) are dependent on ambient temperature (AT) and can be critical for maintaining body and reticulorumen temperature (RT) in cold conditions. The objective of this study was to determine the effects of FWT and FT on RT fluctuations, and of AT on RT and drinking and eating behaviors in late-lactation cows during cold exposure. Data were collected from 16 multiparous lactating cows for four 6-d periods during the autumn and winter seasons. The cows (224 ± 36 days in milk; mean ± SD) had an average milk yield (MY) of 24.8 ± 4.97 kg/d and RT of 38.84 ± 0.163 °C. Daily average AT ranged from 4.38 to 17.25 °C. The effects of the temperature and amount of the ingested water or feed on RT change and recovery time, and the effect of the daily AT on RT, feed and water intake, and drinking, eating, and rumination behaviors were analyzed using the generalized additive mixed model framework. Reticulorumen temperature change and recovery time were affected by FWT (+0.0596 °C/°C and -1.27 min/°C, respectively), but not by FT. The amount of the ingested free water and feed affected RT change (-0.108 °C/kg drink size and -0.150 °C/kg meal size, respectively), and RT recovery time (+2.13 min/kg drink size and + 3.71 min/kg meal size, respectively). Colder AT decreased RT by 0.0151 °C/°C between 9.91 and 17.25 °C AT. Cows increased DM intake (DMI) by 0.365 kg/d per 1 °C drop in AT below 10.63 °C, but with no increase in MY. In fact, MY:DMI decreased by 0.0106/°C as AT dropped from 17.25 to 4.38 °C. Free water intake (FWI) was reduced by 0.0856 FWI:DMI/°C as AT decreased from 17.25 to 8.27 °C. Cold exposure influenced animal behavior with fewer drink and meal bouts (-0.432 and -0.290 bouts/d, respectively), larger drink sizes (+0.100 kg/bout), and shorter rumination time (-5.31 min/d) per 1 °C decrease in AT from 17.25 °C to 8.77, 12.53, 4.38, and 10.32 °C, respectively. In conclusion, exposure to low AT increased feed intake, reduced water intake, and changes in eating, drinking and rumination behaviors of dairy cows in late lactation. Additionally, the consequences of cold exposure on cows may be aggravated by ingestion of feed and free water at temperatures lower than the body, potentially impacting feed efficiency due to the extra energetic cost of thermoregulation.

Periparturient Changes in Voluntary Intake, Digestibility, and Performance of Grazing Zebu Beef Cows with or without Protein Supplementation.

We aimed to understand the changes in nutritional parameters and performance of beef cows during the peripartum, whether receiving or not receiving protein supplements. Forty cows were used, divided into two treatments: CON-mineral mix and SUP-protein supplementation. Digestibility trial was performed at 45, 30, and 15 days (d) before the parturition and at 20 and 40 d of lactation. The ADG of cows pre- and postpartum was recorded along with the BCS in gestational (GT) and maternal (MT) tissues in the prepartum. There was an effect of treatment and period (p ≤ 0.044) for intakes of DM and CP. The forage intake was similar (p > 0.90) but varied with the effect of days related to parturition (p < 0.001). There was a 14.37% decrease in DM intake from d -30 to d -15 of prepartum. In the postpartum, at 20 d of lactation, there was an increase of 72.7% in relation to d -15 of prepartum. No differences were observed in postpartum ADG or BCS at parturition and postpartum (p ≥ 0.12). However, higher total and MT ADG (p ≤ 0.02) were observed in animals receiving supplementation, while ADG in GT remained similar (p > 0.14). In conclusion, there is a decrease in intake for pregnant cows close to parturition and greater performance of animals supplemented in prepartum.

Effects of finisher diet nutrients density and slaughter age on energy and protein efficiency, productive and economic performance and meat quality of broilers.

BACKGROUND: The current broilers have been greatly optimized for weight gain and breast yield, which necessitates the provision of nutrients-dense diets for maximum potential. OBJECTIVES: The current study aimed to evaluate the effect of finisher diet nutrients density (ND) on energy and protein efficiency, productive and economic performance and breast meat quality of broilers raised until different slaughter age. METHODS: A total of 600 23-day-old broiler male chicks (Cobb-500) were assigned to 10 treatments with six replicates and 10 birds each. Experimental treatments were included factorial arrangement of five increment (2.5%) levels of finisher diet ND (92.5%, 95%, 97.5%, 100% and 102.5% as strain recommendation) and slaughtered at 38 or 46 days of age. The relative difference in the energy level of experimental diets was used to increase ND levels at the same ratio. RESULTS: Feed intake (FI) and breast meat quality traits exception water holding capacity (WHC) were not affected by finisher diet ND. In response to increasing finisher diet ND, energy and protein efficiency, productive traits, bio-economic index (BEI) and breast relative weight (BRW) linearly improved. However, residual feed intake and breast meat WHC improved with a quadratic trend. By using broken-line regression analysis, the optimum dietary ND was obtained at 97.5%-102% of strain recommendation. Energy and protein efficiency, feed conversion ratio and BEI deteriorated by prolonging rearing period. The BRW, meat lightness (L*), redness (a*), hue angle (h*) and WHC values for the birds slaughtered at 46 days of age were significantly higher, and cooking loss was lower than those slaughtered at 38 days old. CONCLUSIONS: Broilers during the finisher period are not able to regulate their FIs with diet ND. The energy and protein efficiency, productive and economic performance were reduced when broilers were fed diluted diet or the rearing period was prolonged.

Oleuropein has hypophagic effects in broiler chicks.

Oleuropein, a phenolic compound derived from olives, has known glucoregulatory effects in mammalian models but effects in birds are unknown. We investigated effects of dietary supplementation and exogenous administration of oleuropein on broiler chick feed intake and glucose homeostasis during the first 7 days post-hatch. One hundred and forty-eight day-of-hatch broiler chicks were randomly allocated to one of four dietary treatments with varying oleuropein concentrations (0, 250, 500, or 1,000 mg/kg). Body weight and breast muscle and liver weights were recorded on day 7. In the next experiment, chicks received intraperitoneal (IP) injections of oleuropein at doses of 0 (vehicle), 50, 100, or 200 mg/kg on day 4 post-hatch, with feed intake and blood glucose levels measured thereafter. Lastly, chicks fed a control diet were fasted and administered intracerebroventricular (ICV) injections of oleuropein at doses of 0, 50, 100, or 200 µg, after which feed intake was recorded. Results indicated that IP and ICV injections led to decreased feed intake, primarily at 60 min post-injection, with effects diminishing by 90 min in the IP study. Blood glucose levels decreased 1-h post-IP injection at higher oleuropein doses. These findings suggest that oleuropein acts as a mild appetite suppressant and influences energy metabolism in broiler chickens.

Incorporating body measurement traits to increase genetic gain of feed efficiency and carcass traits in Japanese Black steers.

The objective of the present study was to comprehensively evaluate whether body measurement traits, including BW and body size, could be used as indicators of genetic selection for feed efficiency and carcass traits in Japanese Black steers. First, we estimated the genetic parameters for body measurements, feed efficiency, and carcass traits. Second, we estimated the correlated responses in feed efficiency and carcass traits when selection was applied to one or multiple body measurement traits. In total, 4,578 Japanese Black steers with phenotypic values of residual feed intake (RFI) and residual BW gain (RG) as feed efficiency traits and carcass weight (CWT) and beef marbling standard (BMS) as carcass traits were used. Eleven body measurement traits were measured at the start and finish of the fattening periods (BMT1 and BMT2, respectively), and their growth during the fattening period (BMT3) was used for genetic analyses. The results of genetic parameters showed that the heritability estimates were low to moderate (0.10-0.66), and the genetic correlations among body measurement traits were also estimated to be positively moderate to high in each measuring point (0.23-0.99). The genetic correlations of body measurement traits with RFI and BMS were estimated to be low (-0.14-0.30 and -0.17-0.35, respectively), but those with CWT were positively low to high (0.12-0.97). The genetic correlation estimates between BMT3 and RG were moderate to high (0.38-0.78). Second, correlated responses were estimated under positive selection for body measurement traits. Positive selection for BMT2 and BMT3 increased CWT and RG; however, positive selection for body measurement traits resulted in no change in RFI and BMS. Favorable directions of genetic gains, which were positive for RG, CWT, and BMS and negative for RFI, were obtained by selection indices, including multiple traits in BMT1. Our results suggest that using only one body measurement trait as an indicator of genetic selection for RFI is difficult. However, body measurement traits can be indirect indicators of improved RG. Our results also suggest that genetic improvement of both RFI and RG without reducing CWT and BMS could be achieved using selection indices that account for a balance of body conformation using multiple body measurement traits in Japanese Black cattle.

The effect of feeding and visiting behavior on methane and hydrogen emissions of dairy cattle measured with the GreenFeed system under different dietary conditions.

The objectives were to investigate the effect of feeding and visiting behavior of dairy cattle on CH4 and H2 production measured with voluntary visits to the GreenFeed system (GF) and to determine whether these effects depended on basal diet (BD) and 3-nitrooxypropanol (3-NOP) supplementation. The experiment involved 64 lactating dairy cattle (146 ± 45 d in milk at the start of trial; mean ± SD) in 2 overlapping crossover trials, each consisting of 2 measurement periods. Cows within block were randomly allocated to 1 of 3 types of BD: a grass silage-based diet consisting of 30% concentrates and 70% grass silage (DM basis), a grass silage- and corn silage-mixed diet consisting of 30% concentrates, 42% grass silage, and 28% corn silage (DM basis), or a corn silage-based diet consisting of 30% concentrates, 14% grass silage, and 56% corn silage (DM basis). Each type of BD was subsequently supplemented with 0 and 60 mg 3-NOP/kg DM in one crossover, or 0 and 80 mg 3-NOP/kg DM in the other crossover. Diets were provided in feed bins which automatically recorded feed intake and feeding behavior, with additional concentrate fed in the GF. All visits to the GF that resulted in a spot measurement of both CH4 and H2 emission were analyzed in relation to feeding behavior (e.g., meal size and time interval to preceding meal) as well as GF visiting behavior (e.g., duration of visit). Feeding and GF visiting behavior was related to CH4 and H2 production measured with the GF, in particular the meal size before a GF measurement and the time interval between a GF measurement and the preceding meal. Relationships between gas production and both feeding and GF visiting behavior were affected both by type of BD and 3-NOP supplementation. With an increase of the time interval between a GF measurement and the preceding meal, CH4 production decreased with 0 mg 3-NOP/kg DM but increased with 60 and 80 mg 3-NOP/kg DM, whereas type of BD did not affect these relationships. In contrast, CH4 production increased with 0 mg 3-NOP/kg DM but decreased with 60 and 80 mg 3-NOP/kg DM upon an increase in the size of the meal preceding a GF measurement. With an increase of the time interval between a GF measurement and the preceding meal, or with a decrease of the size of the meal preceding a GF measurement, H2 production decreased for all treatments, although the effect was generally somewhat stronger for 60 and 80 mg 3-NOP/kg DM than for 0 mg 3-NOP/kg DM. Hence, the timing of GF measurements next to feeding and GF visiting behavior are essential when assessing the effect of dietary treatment on the production of CH4 and H2 in a setting where a spot sampling device such as a GF is used and where the measurements depend on voluntary visits from the cows.

Genetic relationships between behavioral traits and feed efficiency traits in lactating Holstein cows.

The evaluation of dairy cow feed efficiency using residual feed intake accounts for known energy sinks. However, behavioral traits may also contribute to the variation in feed efficiency. Our objective was to estimate the heritability and repeatability of behavioral traits and their genetic correlations with feed efficiency and its components in lactating Holstein cows. The first data set consisted of 36,075 daily rumination and lying time records collected using a SMARTBOW ear tag accelerometer (Zoetis, Parsippany, NJ) and 6,371 weekly feed efficiency records of 728 cows from the University of Wisconsin-Madison. The second data set consisted of 59,155 daily activity records, measured as number of steps, recorded by pedometers (AfiAct; S.A.E. Afikim, Kibbutz Afikim, Israel), and 8,626 weekly feed efficiency records of 635 cows from the University of Florida. Feed efficiency and its components included dry matter intake, change in body weight, metabolic body weight, secreted milk energy, and residual feed intake. The statistical models included the fixed effect of cohort, lactation number, and days in milk, and the random effects of animal and permanent environment. Heritability estimates for behavioral traits using daily records were 0.19 ± 0.06 for rumination and activity, and 0.37 ± 0.07 for lying time. Repeatability estimates for behavioral traits using daily data ranged from 0.56 ± 0.02 for activity to 0.62 ± 0.01 for lying time. Both heritability and repeatability estimates were larger when weekly records instead of daily records were used. Rumination and activity had positive genetic correlations with residual feed intake (0.40 ± 0.19 and 0.31 ± 0.22, respectively) while lying time had a negative genetic correlation with this residual feed intake (-0.27 ± 0.11). These results indicate that more efficient cows tend to spend more time lying and less time active. Additionally, less efficient cows tend to eat more and therefore also tend to ruminate longer. Overall, sensor-based behavioral traits are heritable and genetically correlated with feed efficiency and its components and, therefore, they could be used as indicators to identify feed efficient cows within the herd.

Effects of residual feed intake on the economic traits of fast-growing meat ducks.

Feed efficiency (FE) is a crucial economic indicator of meat duck production. The objective of this study was to assess the impact of residual feed intake (RFI), defined as the difference between the actual and expected feed intake based on animal's production and maintenance requirements, on the growth performance (GP), slaughter and internal organ characteristics of fast-growing meat ducks. In total, 1,300 healthy 14-day-old male fast-growing meat ducks were housed in individual cages until slaughter at the age of 35 d. The characteristics of the carcass and internal organs of 30 ducks with the highest RFI (HRFI) and the lowest RFI (LRFI) were respectively determined. RFI, the feed conversion ratio (FCR), and average day feed intake (ADFI) were significantly lower in the LRFI group than the HRFI group (P < 0.001), while there were no significant differences in marketing BW or BW gain (BWG) (P > 0.05). The thigh muscle and lean meat yields were higher, and the abdominal fat content was lower (P < 0.001) in the LRFI group, while there were no significant differences in other carcass traits between the groups (P > 0.05). The liver and gizzard yields were significantly higher (P < 0.001) in the LRFI group, while there were no significant differences (P > 0.05) in intestinal length between the groups. RFI was highly positively correlate with FCR and ADFI (P < 0.01), but negatively correlated the yields of thigh muscle, lean meat, liver, and gizzard, and positively correlated with abdominal fat content. These results indicate that selection for low RFI could improve the FE of fast-growing meat ducks without affecting the marketing BW and BWG, while increasing yields of thigh muscle and lean meat and reducing abdominal fat content. These findings offer useful insights into the biological processes that influence FE of fast-growing meat ducks.

Multi-omics unveils tryptophan metabolic pathway as a key pathway influencing residual feed intake in Duroc swine.

The genetic trait of residual feed intake (RFI) holds considerable importance in the swine industry. Recent research indicates that the gut microbiota of pigs plays a pivotal role in the manifestation of the RFI trait. Nevertheless, the metabolic pathways involved in the functioning of these microorganisms remain elusive. Thus, based on the ranking of the RFI trait in Duroc pigs, the present study selected the top 10 and bottom 10 pigs as the experimental subjects. The distribution and metabolite differences of cecal microbiota were analyzed using 16S rRNA gene sequencing and liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques. The low RFI cecal group was named LRC, and the high RFI cecal group was named HRC. The results indicate that the LRC group had lower RFI, feed conversion ratio (FCR), average daily feed intake (ADFI) (p < 0.001), and thinner backfat (p < 0.05) compared with the HRC group. We simultaneously recorded the foraging behavior as well, the LRC group had a significant increase in total time spent at the feeder per day (TPD) (p < 0.05) and a significant increase in average feed intake per mins (AFI) and the number of visits to the feeder per day (NVD) compared to the HRC group (p < 0.001). Clostridium_XVIII, Bulleidia, and Intestinimonas were significantly enriched in the LRC group (p < 0.01), while Sutterella, Fusobacterium, and Bacteroides were significantly increased in the HRC group (p < 0.01). In the metabolome, we detected 390 (248 metabolites up and 142 down in the LRC compared with HRC), and 200 (97 metabolites up and 103 down in the LRC compared with HRC) differential metabolites in positive and negative ionization modes. The comprehensive analysis found that in the LRC group, Escherichia and Eubacterium in the gut may increase serotonin content, respectively. Bacteroides may deplete serotonin. We suggest that the RFI may be partly achieved through tryptophan metabolism in gut microbes. In individuals with low RFI, gut microbes may enhance feed efficiency by enhancing host synthesis and metabolism of tryptophan-related metabolites.

Detection and characterization of copy number variation in three differentially-selected Nellore cattle populations.

Introduction: Nellore cattle (Bos taurus indicus) is the main beef cattle breed raised in Brazil. This breed is well adapted to tropical conditions and, more recently, has experienced intensive genetic selection for multiple performance traits. Over the past 43 years, an experimental breeding program has been developed in the Institute of Animal Science (IZ, Sertaozinho, SP, Brazil), which resulted in three differentially-selected lines known as Nellore Control (NeC), Nellore Selection (NeS), and Nellore Traditional (NeT). The primary goal of this selection experiment was to determine the response to selection for yearling weight (YW) and residual feed intake (RFI) on Nellore cattle. The main objectives of this study were to: 1) identify copy number variation (CNVs) in Nellore cattle from three selection lines; 2) identify and characterize CNV regions (CNVR) on these three lines; and 3) perform functional enrichment analyses of the CNVR identified. Results: A total of 14,914 unique CNVs and 1,884 CNVRs were identified when considering all lines as a single population. The CNVRs were non-uniformly distributed across the chromosomes of the three selection lines included in the study. The NeT line had the highest number of CNVRs (n = 1,493), followed by the NeS (n = 823) and NeC (n = 482) lines. The CNVRs covered 23,449,890 bp (0.94%), 40,175,556 bp (1.61%), and 63,212,273 bp (2.54%) of the genome of the NeC, NeS, and NeT lines, respectively. Two CNVRs were commonly identified between the three lines, and six, two, and four exclusive regions were identified for NeC, NeS, and NeT, respectively. All the exclusive regions overlap with important genes, such as SMARCD3, SLC15A1, and MAPK1. Key biological processes associated with the candidate genes were identified, including pathways related to growth and metabolism. Conclusion: This study revealed large variability in CNVs and CNVRs across three Nellore lines differentially selected for YW and RFI. Gene annotation and gene ontology analyses of the exclusive CNVRs to each line revealed specific genes and biological processes involved in the expression of growth and feed efficiency traits. These findings contribute to the understanding of the genetic mechanisms underlying the phenotypic differences among the three Nellore selection lines.

Effects of an herbal adaptogen feed-additive on feeding-related hypothalamic neuropeptides in chronic cyclic heat-stressed chickens.

Heat stress (HS) is a global serious issue in the poultry industry with numerous adverse effects, including increased stress, depressed feed intake (FI), poor growth performance and higher mortality. Herbal adaptogens, plant extracts considered as stress response modifiers, are metabolic regulators that improve an organism's ability to adapt to and minimize damage from environmental stresses. Previously, we showed that herbal adaptogen supplementation increased FI and body weight (BW) of broiler (meat-type) chickens reared under HS conditions. Therefore, we hypothesized that these effects may be mediated through modulation of hypothalamic feeding-related neuropeptides. Male Cobb 500 chicks were reared in 12 environmental chambers with three diets: a corn-soybean-based diet (C) and two herbal adaptogen-supplemented diets at 500 g/1000 kg (NR-PHY-500) and 1 kg/1000 kg (NR-PHY-1000). Broilers in 9 chambers were exposed to chronic cyclic HS (35 °C for 8 h/day) from d29 to d42, while 3 chambers were maintained at 24 °C (thermoneutral, TN) for all 42 days. Hypothalamic samples were collected on d42 from each group, both before the onset of HS (Pre-HS) that day and after 3 h of HS (post-HS). Hypothalamic expressions of neuropeptide Y (NPY) receptors Y4 and Y7, Corticotropin-releasing hormone (CRH), orexin receptor 1 (ORXR1), melanocortin receptors (MC1R, MC4R, and MC5R), visfatin and neurosecretory protein GL (NPGL) genes were significantly upregulated by adaptogen supplementation. The hypothalamic expression of MC2R was affect by period, with a significant upregulation during post-HS phase. There was a significant period by treatment interaction for hypothalamic orexin and adiponectin expression. The hypothalamic expression of NPY, Y1, Y2, Y5, Y6, proopiomelanocortin (POMC), cocaine and amphetamine regulated transcript (CART), agouti-related peptide (AgRP), ORXR2, AdipR1/2, MC3R, and ghrelin was not affected by diet supplementation nor by HS exposure. In conclusion, these findings suggest that in-feed supplementation of adaptogen might improve FI and growth via modulation of hypothalamic feeding-related neuropeptides in heat-stressed broilers.

Performance and incidence of diarrhea in suckling Jersey calves supplemented with mineral-vitamin complex and Virginiamycin.

The rearing of calves is an essential activity of a dairy system, as it impacts the future production of these animals. This study aims to evaluate the incidence of diarrhea, performance, and blood parameters of suckling calves that received mineral-vitamin supplementation in milk plus virginiamycin that was offered in milk (via the abomasum) or by esophageal tube (via the rumen). Twenty-seven calves were used, from the first week to 60 days of age, submitted to the following treatments: CONTROL, without supplementation; MILK, supplementation of 20 g of a mineral-vitamin complex with 100 mg of virginiamycin, diluted in milk; RUMEN, supplementation of 20 g of a mineral-vitamin complex diluted in milk and 100 mg of virginiamycin in gelatin capsules via an esophageal applicator. MILK and RUMEN calves had lower fecal consistency scoring, fewer days with scores 2 and 3 throughout the experimental period, and lower spending on medication compared to the CONTROL animals. Supplemented calves had higher fat and protein intake and reached feed intake of 600 g earlier than CONTROL animals, but did not differ in performance and hematological parameters. Supplementation with virginiamycin and vitamin-mineral complex for suckling calves reduced the incidence and days of diarrhea, and reduced medication costs, with no difference in performance, but the supplemented animals had higher initial protein and fat intake and reached targeted feed intake earlier to begin the weaning process.

Gut-brain bidirectional determination in regulating the residual feed intake of small-sized meat ducks.

The gut-brain axis is essential in maintaining the homeostasis of neuronal system, endocrine system, and intestinal microbiota in both the afferent and efferent directions. This axis is considered to be a key mechanism that regulates feed efficiency (FE). This study aimed to investigate the regulatory mechanisms of gut-brain axis-related genes on the residual feed intake (RFI) in H-strain small-sized meat ducks. A total of 500 ducks with similar initial BW (635.2 ± 15.1 g) were selected and reared in the same experimental facility until slaughter at 42 d of age. RFI was calculated from the average daily gain (ADG), average daily feed intake (ADFI), and metabolic body weight (MBW0.75). Thirty high-RFI (H-RFI) and 30 low-RFI (L-RFI) birds were selected for further evaluation of growth performance, carcass characteristics, and blood biochemical parameter measurements. Six L-RFI and 6 H-RFI birds were then subjected to hypothalamic transcriptomic and cecal microbial sequencing analyses. Results indicated that L-RFI birds exhibited lower production performance (ADFI, FCR, and RFI) and blood biochemical indices (total cholesterol and ghrelin content) compared with H-RFI birds (P < 0.05). Gene expression differed significantly between the L-RFI and H-RFI birds, with 70 upregulated and 50 downregulated genes. The bacterial communities of L-RFI birds showed higher abundances of Bacteroides, Bifidobacterium, and Lactococcus, and lower abundances of Erysipelatoclostridium, Parasutterella, Fournierella, and Blautia compared with H-RFI birds (P < 0.05). Interactive analysis revealed bacterial communities associated with FE were significantly correlated with hypothalamic genes (P < 0.05), for example, Bacteroides was positively correlated with DGKH and LIPT2, while negatively correlated with CAPN9, GABRD, and PDE1A. Bifidobacterium showed significant correlations with ATP2A3, CALHM6, and TMEM121B. Overall, RFI was a crucial indicator of FE, regulated by interactions between brain gene expression and gut microbiota through cAMP signaling, neuroactive ligand-receptor interaction, and calcium signaling pathways. Notably, increased expression of hypothalamic genes and abundance of carbohydrate-utilization microbiota in L-RFI meat ducks improved FE by enhancing energy metabolism and volatile fatty acids absorption.

Behavioral consistency of competitive behaviors and feeding patterns in lactating dairy cows across stocking densities at the feed bunk.

Introduction: High feed bunk stocking densities can differentially impact individual dairy cows' competitive behaviors, feeding patterns, and feed efficiency. Our objective was to manipulate feed bunk stocking densities to evaluate intra-individual behavioral consistency across stocking densities and quantify associations with feed efficiency and production. Methods: Thirty-two primiparous (130.7 ± 29.0 days in milk, DIM) and 32 multiparous (111.3 ± 38.3 DIM) lactating Holstein cows were housed with 32 roughage intake control (RIC) bins. Each cow was assigned to share 8 bins with others of the same parity and similar body weight (16 cows/block; 2:1 feed bunk stocking density except during tests). Competition and feeding patterns were evaluated via video and RIC data, respectively, at 3 stocking densities (1:1, 2:1, 4:1 cows/bin) during 1-h tests (2 tests/stocking density; 6 tests/cow) following 2 h feed deprivation. Residual feed intake (RFI) was calculated across the 45-d study as the difference between observed and predicted dry matter intake (DMI) after accounting for known energy sinks. Linear mixed models were used to evaluate the overall impact of test stocking density on competition and feeding patterns. To evaluate intra-individual consistency between stocking densities, individual stability statistic (ISS) scores were computed. Correlational relationships were determined between RFI and ISS scores. Results and dicsussion: Cows displayed the most competitive behaviors at 2:1 stocking density (p < 0.0001) but experienced the highest rate of contacts per minute of eating time at 4:1 (1:1 vs. 2:1 vs. 4:1: 0.09 vs. 0.95 vs. 1.60 contacts/min; p < 0.0001). Feeding patterns were modulated as stocking density increased; eating rate increased (0.16 vs. 0.18 vs. 0.22 kg/min; p < 0.001) as eating time (40.3 vs. 28.2 vs. 14.6 min; p < 0.001) and DMI decreased (6.3 vs. 5.1 vs. 3.0 kg; p < 0.001). As stocking density doubled, individuals remained consistent (p = 0.018) in time spent near others actively eating and tended to remain consistent in competition behavior and feeding patterns (0.053 ≤ p ≤ 0.094). Between 2:1 and 4:1, cows with higher DMI and milk production were more consistent in first-visit DMI and duration. Feed efficiency was not associated with behavioral consistency across the tests (p ≥ 0.14). Nonetheless, feed bunk stocking density has behavioral implications which should be considered in nutritional management decisions.

Dataset from the literature on the ingestive behaviour of grazing ruminants.

The dataset described in this paper was constructed from 90 publications available from bibliographic databases. It presents the values of various quantitative components of ingestive behaviour of grazing ruminants (bite weight, biting rate, intake rate, grazing time, etc.). These values were coded according to the experimental factors tested and described in the publications, of a temporal nature (season, year, grazing cycle) or linked to the sward management strategies (overall density bulk or of the stems, the stage regrowth or the fertilization) or other pasture management strategies (herbage allowance, pasture access time, stocking rate). Other essential factors were also coded, specifying the characteristics of the grass grazed (height of the grass, apparent density, forage species), the characteristics of the animals used (species, stage, age and body weight) or the measurement methods of behavioural components. This coding process aims to facilitate the identification of subsets of data of interest, and have been analysed for example to highlight the main components determining bite weight or the components linking bite weight to intake rate and daily intake (see reference).

Estimation of genetic parameters for maintenance energy requirements and residual feed intake in Nellore cattle.

We estimated heritabilities and genetic and phenotypic correlation estimates for maintenance energy requirements (NEmR), residual feed intake (RFI), growth, carcass and reproductive indicator traits, using data from 41 feed efficiency trials in Brazil, comprising 4381 males and females. Continuous traits were analysed using a linear animal model and threshold traits were analysed using a threshold animal model. The heritability estimates were low for RFI (0.190) and NEmR (0.193); other heritabilities were mainly moderate (growth and carcass traits) or high (sexual precocity traits). The genetic correlation of RFI with NEmR was high (0.701). The genetic correlations of NEmR were low with carcass and reproductive traits, and moderate with growth traits. Thus, selection to improve weaning weight and female sexual precocity indicator traits would not affect maintenance energy requirement. Genetic selection to reduce maintenance energy requirements is feasible and would also reduce DMI and RFI. Selection to improve RFI can be used to identify animals with lower maintenance energy requirements. Long-term selection to reduce RFI and NEmR would have favourable effects on yearling weight, carcass muscle indicator traits and female sexual precocity. Genetic (co)variance component estimates for NEmR, in conjunction with economic values of selection criteria, may be used to develop novel approaches for genetic selection to improve efficiency of beef production.

Impact of the leptin receptor gene on pig performance and quality traits.

The recessive T allele of the missense polymorphism rs709596309 C > T of the leptin receptor gene is associated with intramuscular fat. However, its overall impact on pork production is still partial. In this work, we investigated the all-round effects of the TT genotype on lean growth efficiency and carcass, meat and fat quality using data from an experiment that compared the performance of 48 TT and 48 C- (24 CT and 24 CC) Duroc barrows. The TT pigs were less efficient for lean growth than the C- pigs. Although heavier, their carcasses had less lean content, were shorter and had lighter loins. Apart from increasing marbling and saturated fatty acid content, changes caused by the TT genotype in meat and fat quality are likely not enough to be perceived by consumers. The effect on visual marbling score exceeded that on intramuscular fat content, which suggests a direct influence of the T allele on the pattern of fat distribution in muscle. With current low-protein diets, the T allele is expected to be cost-effective only in niche markets where a very high level of marbling is critical.

Dry matter intake in US Holstein cows: exploring the genomic and phenotypic impact of milk components and body weight composite.

Large data sets allow estimating feed required for individual milk components or body maintenance. Phenotypic regressions are useful for nutrition management, but genetic regressions are more useful in breeding programs. Dry matter intake (DMI) records from 8,513 lactations of 6,621 Holstein cows were predicted from phenotypes or genomic evaluations for milk components and body size traits. The mixed models also included days in milk, age-parity subclass, trial date, management group, and body weight change during 28- and 42-d feeding trials in mid-lactation. Phenotypic regressions of DMI on milk (0.014 ± 0.006), fat (3.06 ± 0.01), and protein (4.79 ± 0.25) were much less than corresponding genomic regressions (0.08 ± 0.03, 11.30 ± 0.47, and 9.35 ± 0.87) or sire genomic regressions multiplied by 2 (0.048 ± 0.04, 6.73 ± 0.94, and 4.98 ± 1.75). Thus, marginal feed costs as fractions of marginal milk revenue were higher from genetic than phenotypic regressions. According to the energy-corrected milk formula, fat production requires 69% more DMI than protein production. In the phenotypic regression, it was estimated that protein production requires 56% more DMI than fat. However, the genomic regression for the animal showed a difference of only 21% more DMI for protein compared with fat, while the sire genomic regressions indicated approximately 35% more DMI for fat than protein. Estimates of annual maintenance in kg DMI / kg body weight/lactation were similar from phenotypic regression (5.9 ± 0.14), genomic regression (5.8 ± 0.31), and sire genomic regression multiplied by 2 (5.3 ± 0.55) and are larger than those estimated by NASEM (2021) based on NEL equations. Multiple regressions on genomic evaluations for the 5 type traits in body weight composite (BWC) showed that strength was the type trait most associated with body weight and DMI, agreeing with the current BWC formula, whereas other traits were less useful predictors, especially for DMI. The Net Merit formula used to weight different genetic traits to achieve an economically optimal overall selection response was revised in 2021 to better account for these estimated regressions. To improve profitability, breeding programs should select smaller cows with negative residual feed intake that produce more milk, fat, and protein.

Metagenomic insights into the relationship between intestinal flora and residual feed intake of meat ducks.

In this study, we sought to determine the effects of intestinal flora on the feed efficiency of meat ducks by evaluating the correlation between intestinal flora and residual feed intake. The F2 generation of Cherry Valley ducks × Runzhou Crested White ducks was used as the study subjects, and feed consumption being recorded from d 21 to 42. RFI was calculated based on growth performance, and 20 low RFI and 20 high RFI ducks were randomly selected to characterize the effect of RFI on growth performance. To analyze the intestinal flora affecting RFI, 16s rDNA sequencing was performed on the contents of 5 intestinal segments from the HR and LR groups, and macrogenomic sequencing was performed on the cecal contents. Feed intake, average daily feed intake, feed conversion ratio, and residual feed intake were lower in low RFI. Analysis of the intestinal flora revealed the cecum to be more highly enriched in the carbohydrate metabolism pathway and less enriched with potentially pathogenic taxa than the other assessed intestinal regions. Further analysis of the cecal microbiota identified nine significantly differentially enriched intestinal flora. In this study, we accordingly identified a basis for the mechanisms underlying the effects of the intestinal flora on meat duck feed efficiency.