Development and application of an efficient genomic mating method to maximize the production performances of three-way crossbred pigs.

Creating synthetic lines is the standard mating mode for commercial pig production. Traditional mating performance was evaluated through a strictly designed cross-combination test at the 'breed level' to maximize the benefits of production. The Duroc-Landrace-Yorkshire (DLY) three-way crossbred production system became the most widely used breeding scheme for pigs. Here, we proposed an 'individual level' genomic mating procedure that can be applied to commercial pig production with efficient algorithms for estimating marker effects and for allocating the appropriate boar-sow pairs, which can be freely accessed to public in our developed HIBLUP software at https://www.hiblup.com/tutorials#genomic-mating. A total of 875 Duroc boars, 350 Landrace-Yorkshire sows and 3573 DLY pigs were used to carry out the genomic mating to assess the production benefits theoretically. The results showed that genomic mating significantly improved the performances of progeny across different traits compared with random mating, such as the feed conversion rate, days from 30 to 120 kg and eye muscle area could be improved by -0.12, -4.64 d and 2.65 cm2, respectively, which were consistent with the real experimental validations. Overall, our findings indicated that genomic mating is an effective strategy to improve the performances of progeny by maximizing their total genetic merit with consideration of both additive and dominant effects. Also, a herd of boars from a richer genetic source will increase the effectiveness of genomic mating further.

Divergent selection for feed efficiency in pigs altered the duodenum transcriptomic response to feed intake and its DNA methylation profiles.

Feed efficiency is a trait of interest in pigs as it contributes to lowering the ecological and economical costs of pig production. A divergent genetic selection experiment from a Large White pig population was performed for 10 generations, leading to pig lines with relatively low- (LRFI) and high- (HRFI) residual feed intake (RFI). Feeding behavior and metabolic differences have been previously reported between the two lines. We hypothesized that part of these differences could be related to differential sensing and absorption of nutrients in the proximal intestine. We investigated the duodenum transcriptome and DNA methylation profiles comparing overnight fasting with ad libitum feeding in LRFI and HRFI pigs (n = 24). We identified 1,106 differentially expressed genes between the two lines, notably affecting pathways of the transmembrane transport activity and related to mitosis or chromosome separation. The LRFI line showed a greater transcriptomic response to feed intake than the HRFI line. Feed intake affected genes from both anabolic and catabolic pathways in the pig duodenum, such as rRNA production and autophagy. Several nutrient transporter and tight junction genes were differentially expressed between lines and/or by short-term feed intake. We also identified 409 differentially methylated regions in the duodenum mucosa between the two lines, while this epigenetic mark was less affected by feeding. Our findings highlighted that the genetic selection for feed efficiency in pigs changed the transcriptome profiles of the duodenum, and notably its response to feed intake, suggesting key roles for this proximal gut segment in mechanisms underlying feed efficiency.NEW & NOTEWORTHY The duodenum is a key organ for the hunger/satiety loop and nutrient sensing. We investigated how the duodenum transcriptome and DNA methylation profiles are affected by feed intakes in pigs. We observed thousands of changes in gene expression levels between overnight-fasted and fed pigs in high-feed efficiency pig lines, but almost none in the related low-feed efficiency pig line.

An across breed, diet and tissue analysis reveals the transcription factor NR1H3 as a key mediator of residual feed intake in beef cattle.

BACKGROUND: Provision of feed is a major determinant of overall profitability in beef production systems, accounting for up to 75% of the variable costs. Thus, improving cattle feed efficiency, by way of determining the underlying genomic control and subsequently selecting for feed efficient cattle, provides a method through which feed input costs may be reduced. The objective of this study was to undertake gene co-expression network analysis using RNA-Sequence data generated from Longissimus dorsi and liver tissue samples collected from steers of two contrasting breeds (Charolais and Holstein-Friesian) divergent for residual feed intake (RFI), across two consecutive distinct dietary phases (zero-grazed grass and high-concentrate). Categories including differentially expressed genes (DEGs) based on the contrasts of RFI phenotype, breed and dietary source, as well as key transcription factors and proteins secreted in plasma were utilised as nodes of the gene co-expression network. RESULTS: Of the 2,929 DEGs within the network analysis, 1,604 were reported to have statistically significant correlations (≥ 0.80), resulting in a total of 43,876 significant connections between genes. Pathway analysis of clusters of co-expressed genes revealed enrichment of processes related to lipid metabolism (fatty acid biosynthesis, fatty acid ß-oxidation, cholesterol biosynthesis), immune function, (complement cascade, coagulation system, acute phase response signalling), and energy production (oxidative phosphorylation, mitochondrial L-carnitine shuttle pathway) based on genes related to RFI, breed and dietary source contrasts. CONCLUSIONS: Although similar biological processes were evident across the three factors examined, no one gene node was evident across RFI, breed and diet contrasts in both liver and muscle tissues. However within the liver tissue, the IRX4, NR1H3, HOXA13 and ZNF648 gene nodes, which all encode transcription factors displayed significant connections across the RFI, diet and breed comparisons, indicating a role for these transcription factors towards the RFI phenotype irrespective of diet and breed. Moreover, the NR1H3 gene encodes a protein secreted into plasma from the hepatocytes of the liver, highlighting the potential for this gene to be explored as a robust biomarker for the RFI trait in beef cattle.

Transcriptomic analysis of intestinal organoids, derived from pigs divergent in feed efficiency, and their response to Escherichia coli.

BACKGROUND: There is increasing interest in using intestinal organoids to study complex traits like feed efficiency (FE) and host-microbe interactions. The aim of this study was to investigate differences in the molecular phenotype of organoids derived from pigs divergent for FE as well as their responses to challenge with adherent and invasive Escherichia coli (E. coli). RESULTS: Colon and ileum tissue from low and high FE pigs was used to generate 3D organoids and two dimensional (2D) monolayers of organoid cells for E. coli challenge. Genome-wide gene expression was used to investigate molecular differences between pigs that were phenotypically divergent for FE and to study the difference in gene expression after challenge with E. coli. We showed, (1) minor differences in gene expression of colon organoids from pigs with low and high FE phenotypes, (2) that an E. coli challenge results in a strong innate immune gene response in both colon and ileum organoids, (3) that the immune response seems to be less pronounced in the colon organoids of high FE pigs and (4) a slightly stronger immune response was observed in ileum than in colon organoids. CONCLUSIONS: These findings demonstrate the potential for using organoids to gain insights into complex biological mechanisms such as FE.

Genome-wide association analysis identify candidate genes for feed efficiency and growth traits in Wenchang chickens.

BACKGROUND: Wenchang chickens are one of the most popular local chicken breeds in the Chinese chicken industry. However, the low feed efficiency is the main shortcoming of this breed. Therefore, there is a need to find a more precise breeding method to improve the feed efficiency of Wenchang chickens. In this study, we explored important candidate genes and variants for feed efficiency and growth traits through genome-wide association study (GWAS) analysis. RESULTS: Estimates of genomic heritability for growth and feed efficiency traits, including residual feed intake (RFI) of 0.05, average daily food intake (ADFI) of 0.21, average daily weight gain (ADG) of 0.24, body weight (BW) at 87, 95, 104, 113 days of age (BW87, BW95, BW104 and BW113) ranged from 0.30 to 0.44. Important candidate genes related to feed efficiency and growth traits were identified, such as PLCE1, LAP3, MED28, QDPR, LDB2 and SEL1L3 genes. CONCLUSION: The results identified important candidate genes for feed efficiency and growth traits in Wenchang chickens and provide a theoretical basis for the development of new molecular breeding technology.

Insights into the influence of diet and genetics on feed efficiency and meat production in sheep.

Feed costs and carcass yields affect the profitability and sustainability of sheep production. Therefore, it is crucial to select animals with a higher feed efficiency and high-quality meat production. This study focuses on the impact of dietary and genetic factors on production traits such as feed efficiency, carcass quality, and meat quality. Diets promote optimal sheep growth and development and provide sufficient protein can lead to higher-quality meat. However, establishing an optimized production system requires careful consideration and balance of dietary parameters. This includes ensuring adequate protein intake and feeding diets with higher intestinal absorption rates to enhance nutrient absorption in the gut. The study identifies specific genes, such as Callipyge, Calpastatin, and Myostatin, and the presence of causal mutations in these genes, as factors influencing animal growth rates, feed efficiency, and meat fatty acid profiles. Additionally, variants of other reported genes, including PIGY, UCP1, MEF2B, TNNC2, FABP4, SCD, FASN, ADCY8, ME1, CA1, GLIS1, IL1RAPL1, SOX5, SOX6, and IGF1, show potential as markers for sheep selection. A meta-analysis of reported heritability estimates reveals that residual feed intake (0.27 ± 0.07), hot carcass weight (0.26 ± 0.05), dressing percentage (0.23 ± 0.05), and intramuscular fat content (0.45 ± 0.04) are moderately to highly heritable traits. This suggests that these traits are less influenced by environmental factors and could be improved through genetic selection. Additionally, positive genetic correlations exist between body weight and hot carcass weight (0.91 ± 0.06), dressing percentage (0.35 ± 0.15), and shear force (0.27 ± 0.24), indicating that selecting for higher body weight could lead to favorable changes in carcass quality, and meat quality.

Effect of monensin on milk production efficiency and milk composition in lactating dairy cows fed modern diets.

Since the US Food and Drug Administration's approval of monensin in 2004, significant nutritional advances have been made to increase feed efficiency and milk fat production. Recent evidence suggests monensin's adverse effect on milk fat percentage may be absent when diets are formulated to address known diet-induced milk fat depression risk factors. Thus, study objectives were to evaluate effects of monensin level on dry matter intake (DMI), milk production and composition, and efficiency of high-producing cows fed diets formulated to optimize milk fat. Ninety-six lactating Holstein cows (36 primiparous, 60 multiparous; 106 ± 17 d in milk [DIM]) were balanced by parity, DIM, and milk production and were randomly assigned to 1 of 12 pens with 8 cows per pen. All cows received 11 g/t monensin for 5 wk after which pens received 1 of 4 dietary treatments (n = 3) formulated to provide 0 (CON), 11 (R11), 14.5 (R14.5), or 18 (R18) g/t monensin for 9 wk. The basal diet was 54% forage, 27% NDF, 29% starch, and 2.3% rumen unsaturated fatty acid load. Pen was the experimental unit and data were analyzed using the Fit Model Procedure of JMP. Effects of treatment, time, and treatment × time interaction were included as fixed effects and pen as a random effect. Least squares means were determined and linear and quadratic contrasts were tested. Dry matter intake tended to decrease linearly with increasing monensin dose. Milk yield, fat percentage, and protein percentage and yield were unaffected by treatment while fat yield was quadratically increased. Milk de novo and mixed fatty acid (FA) yields (g/d) increased quadratically with monensin whereas preformed FA linearly decreased during the experimental period. Energy-corrected milk (ECM) was quadratically increased by monensin. Milk urea nitrogen concentrations increased linearly with increasing monensin dose. Monensin linearly increased feed efficiency (ECM/DMI, 3.5% fat-corrected milk/DMI, and solids-corrected milk/DMI). Body weight gain did not differ between treatments. Estimated dietary energy tended to increase linearly with increasing monensin level. These data suggest monensin improves component-corrected milk production efficiency, estimated dietary energy, and does not negatively affect milk fat percentage or FA profile.

Host and rumen microbiome contributions to feed efficiency traits in Holstein cows.

It is now widely accepted that dairy cow performance is influenced by both the host genome and rumen microbiome composition. The contributions of the genome and the microbiome to the phenotypes of interest are quantified by heritability (h2) and microbiability (m2), respectively. However, if the genome and microbiome are included in the model, then the h2 reflects only the contribution of the direct genetic effects quantified as direct heritability (hd2), and the holobiont effect reflects the joint action of the genome and the microbiome, quantified as the holobiability (ho2). The objectives of this study were to estimate h2, hd2,m2, and ho2 for dry matter intake, milk energy, and residual feed intake; and to evaluate the predictive ability of different models, including genome, microbiome, and their interaction. Data consisted of feed efficiency records, SNP genotype data, and 16S rRNA rumen microbial abundances from 448 mid-lactation Holstein cows from 2 research farms. Three kernel models were fit to each trait: one with only the genomic effect (model G), one with the genomic and microbiome effects (model GM), and one with the genomic, microbiome, and interaction effects (model GMO). The model GMO, or holobiont model, showed the best goodness-of-fit. The hd2 estimates were always 10% to 15% lower than h2 estimates for all traits, suggesting a mediated genetic effect through the rumen microbiome, and m2 estimates were moderate for all traits, and up to 26% for milk energy. The ho2 was greater than the sum of hd2 and m2, suggesting that the genome-by-microbiome interaction had a sizable effect on feed efficiency. Kernel models fitting the rumen microbiome (i.e., models GM and GMO) showed larger predictive correlations and smaller prediction bias than the model G. These findings reveal a moderate contribution of the rumen microbiome to feed efficiency traits in lactating Holstein cows and strongly suggest that the rumen microbiome mediates part of the host genetic effect.

Dietary supplementation of rumen native microbes improves lactation performance and feed efficiency in dairy cows.

Objectives were to determine the effects of 2 dietary microbial additives supplemented to diets of Holstein cows on productive performance and feed efficiency. One-hundred and 17 Holstein cows were enrolled at 61 d (31 to 87 d) postpartum in a randomized complete block design experiment. Cows were blocked by parity group, as nulliparous or multiparous cows and, within parity, by pre-treatment energy-corrected milk yield. Within block, cows were randomly assigned to one of 3 treatments administered as top-dress for 140 d. Treatments consisted of either 100 g of corn meal containing no microbial additive (CON; 15 primiparous and 25 multiparous), 100 g of corn meal containing 5 g of a mixture of Clostridium beijerinckii and Pichia kudriavzevii (G1; 4 × 107 cfu of C. beijerinckii and 1 × 109 cfu of P. kudriavzevii; 14 primiparous and 24 multiparous), or 100 g of corn meal containing 5 g of a mixture of C. beijerinckii, P. kudriavzevii, Butyrivibrio fibrisolvens, and Ruminococcus bovis (G2; 4 × 107 cfu of C. beijerinckii, 1 × 109 cfu of P. kudriavzevii, 1 × 108 cfu of B. fibrisolvens, and 1 × 108 cfu of R. bovis; 15 primiparous and 24 multiparous). Intake of DM, milk yield, and BW were measured daily, whereas milk composition was analyzed at each milking 2 d a week, and body condition was scored twice weekly. Milk samples were collected on d 60 and 62 in the experiment and analyzed for individual fatty acids. The data were analyzed with mixed-effects models with orthogonal contrast to determine the impact of microbial additive (MA; CON vs. 1/2 G1 + 1/2 G2) and type of microbial additive (TMA; G1 vs. G2). Results are described in sequence as CON, G1, and G2. Intake of DM (22.2 vs. 22.4 vs. 22.4 kg/d), BW (685 vs. 685 vs. 685 kg) and the daily BW change (0.40 vs. 0.39 vs. 0.39 kg/d) did not differ among treatments; however, feeding MA tended to increase BCS (3.28 vs. 3.33 vs. 3.36). Supplementing MA increased yields of milk (39.9 vs. 41.3 vs. 41.5 kg/d), ECM (37.9 vs. 39.3 vs. 39.9 kg/d), fat (1.31 vs. 1.37 vs. 1.40 kg/d), total solids (4.59 vs. 4.75 vs. 4.79 kg/d), and ECM per kg of DMI (1.72 vs. 1.76 vs. 1.80 kg/kg). Furthermore, cows fed MA increased yields of pre-formed fatty acids in milk fat (>16C; 435 vs. 463 vs. 488 g/d), particularly unsaturated fatty acids (367 vs. 387 vs. 410 g/d), such as linoleic (C18:2 cis-9, cis-12; 30.9 vs. 33.5 vs. 35.4 g/d) and α-linolenic acids (C18:3 cis-9, cis-12, cis-15; 2.46 vs. 2.68 vs. 2.82 g/d) on d 60 and 62 in the experiment. Collectively, supplementing G1 and G2 improved productive performance of cows with no differences between the 2 MA.

Growth and feed efficiency of Nordic Red Dairy Cattle, Holstein, and their F1 crossbreeds when limiting feed energy concentration in prepubertal heifers.

Milk production and overall dairy farm economics depend on rearing dairy heifers. This study investigated the presence of a genotype by environment interaction in Holstein (HOL), Nordic Red Dairy Cattle (RDC), and their F1 crossbreeds (HOLxRDC) when provided different feed rations. The aim of our study was to assess how different energy concentrations in feed rations affect growth, body condition scores, feed intake, and feed efficiency in the 3 groups during the prepubertal period. The 3 breed groups were randomly allocated to receive either a standard or a low energy feed ration. HOL heifers exhibited reduced growth and a lower body condition score when they were fed the low energy feed ration. In contrast, the RDC heifers demonstrated similar growth rates with the different feed rations and maintained similar body condition scores irrespective of feed energy concentration. HOLxRDC crossbred heifers performed as an intermediate between the HOL and RDC groups. There were significant differences in dry matter intake and energy intake in the HOL and HOLxRDC groups depending on feed ration treatment. The RDC heifers had similar feed intake irrespective of treatment. There were no significant differences in the feed conversion ratio between breeds and feed treatments. These results indicate the presence of a genotype by environment interaction in prepubertal HOL and RDC heifers in response to differences in feed ration treatment. Due to the influence of prepubertal growth on future milk production, reproduction, and health status, it is important to be aware of breed-specific requirements during the prepubertal period, particularly in mixed-breed and crossbred groups, to optimize growth rates and production potential.

Estimates of genetic parameters for rumination time, feed efficiency, and methane production traits in first-lactation Holstein cows.

The large-scale recording of traits such as feed efficiency (FE) and methane emissions (ME) for use in genetic improvement programs is complex, costly, and time-consuming. Therefore, heritable traits that can be continuously recorded in dairy herds and are correlated with FE and ME traits could provide useful information for genetic evaluation. Rumination time has been suggested to be associated with FE, methane production (MeP; ME in g/d), and production traits at the phenotypic level. Therefore, the objective of this study was to investigate the genetic relationships among rumination time (RT), FE, methane and production traits using 7,358 records from 656 first-lactation Holstein cows. The estimated heritabilities were moderate for RT (0.45 ± 0.14), MeP (0.36 ± 0.12), milk yield (0.40 ± 0.08), fat yield (0.29 ± 0.06), protein yield (0.32 ± 0.07), and energy-corrected milk (0.28 ± 0.07), but were low and nonsignificant for FE (0.15 ± 0.07), which was defined as the residual of the multiple linear regression of DMI on energy-corrected milk and metabolic body weight. A favorable negative genetic correlation was estimated between RT and MeP (-0.53 ± 0.24), whereas a positive favorable correlation was estimated between RT and energy-corrected milk (0.49 ± 0.11). The estimated genetic correlation of RT with FE (-0.01 ± 0.17) was not significantly different from zero but showed a trend of a low correlation with dry matter intake (0.21 ± 0.13). These results indicate that RT is genetically associated with MeP and milk production traits, but high standard errors indicate that further analyses should be conducted to verify these findings when more data for RT, MeP, and FE become available.

Effect of monensin and live-cell yeast supplementation on lactation performance, feeding behavior, and total-tract nutrient digestibility in dairy cows.

The objective of this study was to evaluate the effects of supplementing monensin (19.8 g/Mg DM TMR; MON) and Saccharomyces cerevisiae CNCM I-1077 live-cell yeasts (Saccharomyces cerevisiae CNCM I-1077; 1 × 1010 cfu/head per day; LCY) on lactation performance, feeding behavior, and total-tract nutrient digestibility of high-producing dairy cows. Sixty-four multiparous Holstein cows (3.2 ± 1.5 lactations; 97 ± 16 DIM, and 724 ± 68 kg of BW at covariate period initiation) and 32 gate feeders were enrolled in a study with a completely randomized design and a 2 × 2 factorial arrangement. Cows and gate feeders were randomly assigned to treatments (16 cows and 8 gate feeders per treatment). Cows were allowed 2 wk to acclimate to feeding gates followed by a 2-wk covariate period. During the acclimation and covariate periods, all cows were fed a diet containing MON and LCY. Following the covariate period, cows were enrolled in a 10-wk treatment period during which cows were randomly assigned to 1 of 4 treatments: (1) a combination of MON and LCY (MON-LCY), (2) MON-CON, (3) CON-LCY, or (4) neither MON nor LCY (CON-CON). Data were analyzed using a mixed model with week as a repeated measure and fixed effects of MON, LCY, week, and all their interactions. Cow (treatment) was included as a random effect. The average covariate period value of each variable was used as a covariate. Three-way interactions were observed for DMI and feed efficiency. Dry matter intake decreased from wk 4 to 5 and wk 8 to 10 in MON-LCY cows compared with CON-CON. No treatment differences were observed for actual or component-corrected milk yield or milk components, except for a tendency for LCY to decrease milk fat yield. Feed efficiency was greater for MON-LCY relative to CON-CON in 4 of 10 wk. Interactions between MON and LCY were observed for dry matter and organic matter digestibility, where both were lower for CON-CON than other treatments. Under the conditions of the present study, feeding dairy cows in a high feed bunk density a combination of MON and LCY can decrease intake and improve feed efficiency without affecting milk production or components. Additionally, monensin and live-cell yeasts may each improve total-tract digestibility based on improvements in DM and OM digestibility.

Assessment of milk metabolites as biomarkers for predicting feed efficiency in dairy sheep.

Estimating feed efficiency (FE) in dairy sheep is challenging due to the high cost of systems that measure individual feed intake. Identifying proxies that can serve as effective predictors of FE could make it possible to introduce FE into breeding programs. Here, 39 Assaf ewes in first lactation were evaluated regarding their FE by 2 metrics, residual feed intake (RFI) and feed conversion ratio (FCR). The ewes were classified into high, medium and low groups for each metric. Milk samples of the 39 ewes were subjected to untargeted metabolomics analysis. The complete milk metabolomic signature was used to discriminate the FE groups using partial least squares discriminant analysis. A total of 41 and 26 features were selected as the most relevant features for the discrimination of RFI and FCR groups, respectively. The predictive ability when utilizing the complete milk metabolomic signature and the reduced data sets were investigated using 4 machine learning (ML) algorithms and a multivariate regression method. The orthogonal partial least squares algorithm outperformed other ML algorithms for FCR prediction in the scenarios using the complete milk metabolite signature (R2 = 0.62 ± 0.06) and the 26 selected features (R2 = 0.62 ± 0.15). Regarding RFI predictions, the scenarios using the 41 selected features outperformed the scenario with the complete milk metabolite signature, where the multilayer feedforward artificial neural network (R2 = 0.18 ± 0.14) and extreme gradient boosting (R2 = 0.17 ± 0.15) outperformed other algorithms. The functionality of the selected metabolites implied that the metabolism of glucose, galactose, fructose, sphingolipids, amino acids, insulin, and thyroid hormones was at play. Compared with the use of traditional methods, practical applications of these biomarkers might simplify and reduce costs in selecting feed-efficient ewes.

Effects of feeding rumen-protected lysine during the postpartum period on performance and amino acid profile in dairy cows: A meta-analysis.

Lysine is one of the limiting AA in the diets of dairy cows and is typically fed as rumen-protected Lys (RPL). We hypothesized that supplementation of RPL during the postpartum period would improve the productive performance in dairy cows. Objectives were to use meta-analytic methods to explore the effects of feeding RPL on performance and blood AA profile in lactating dairy cows. An additional objective was to identify an optimal concentration (%) of Lys in MP (LYSMP) and determine if responses to LYSMP were associated with the concentration (%) of Met in MP (METMP). The literature was systematically reviewed, and 13 experiments, comprising 40 treatment means and 594 lactating cows, were included in the meta-analysis. All experiments had a nonsupplemental control (CON; n = 17 treatment means), or a group supplemented with RPL (n = 23 treatment means). Cows supplemented with RPL were supplied additionally with a mean (±standard deviation) 19.3 ± 10.3 g/d metabolizable Lys (5.1-40.6 g/d). Meta-analytical statistics were used to estimate the weighted mean difference in STATA. Mixed models were fitted to the data to investigate the linear and quadratic effects of LYSMP, METMP, and interactions between LYSMP and METMP. All models included the random effect of experiment and weighting by the inverse of the SE of the means squared. Cows that began receiving RPL in early lactation (≤90 DIM) or for an extended duration (≥70 DIM) produced 1.51 kg/d more milk compared with CON cows. Increasing digestible LYSMP from 6.5% to 8.5% linearly increased yields of milk, FCM, ECM, and milk fat by 1.8, 2.5, 2.4, and 0.10 kg/d, respectively, and tended to increase milk protein yield and body weight gain by 0.07 and 0.09 kg/d, respectively, without a concurrent increase in DMI. Interactions between the linear effects of LYSMP and METMP were observed for FCM/DMI or ECM/DMI. In a diet with low METMP (e.g., 1.82% of MP), a digestible supply of 7.40% LYSMP would result in 1.46 and 1.47 kg/kg FCM/DMI or ECM/DMI, respectively; however, with high digestible METMP (e.g., 2.91% of MP), supplying 7.40% of digestible LYSMP would result in 1.68 and 1.62 kg/kg FCM/DMI or ECM/DMI, respectively. Increasing digestible LYSMP from 6.5% to 8.5% linearly increased blood concentrations of Lys by 16.6 µM, whereas blood concentrations of Met and Ala decreased by 4.6 and 6.0 µM, respectively. Nevertheless, an interaction was also observed between LYSMP and METMP for blood concentrations of total EAA because as METMP increased, the positive response to LYSMP on total EAA was also increased, suggesting a competitive mobilization of AA and their utilization in various body tissues. Only 4 out of the 13 experiments in this meta-analysis involved primiparous cows; thus, insufficient data were available to understand the role of supplemental RPL in primiparous cows. Collectively, feeding RPL improved productive performance, and the increments were maximized up to 9.25% of LYSMP in multiparous dairy cows.

The Resilient Dairy Genome Project-A general overview of methods and objectives related to feed efficiency and methane emissions.

The Resilient Dairy Genome Project (RDGP) is an international large-scale applied research project that aims to generate genomic tools to breed more resilient dairy cows. In this context, improving feed efficiency and reducing greenhouse gases from dairy is a high priority. The inclusion of traits related to feed efficiency (e.g., dry matter intake [DMI]) or greenhouse gases (e.g., methane emissions [CH4]) relies on available genotypes as well as high quality phenotypes. Currently, 7 countries (i.e., Australia, Canada, Denmark, Germany, Spain, Switzerland, and United States) contribute with genotypes and phenotypes including DMI and CH4. However, combining data are challenging due to differences in recording protocols, measurement technology, genotyping, and animal management across sources. In this study, we provide an overview of how the RDGP partners address these issues to advance international collaboration to generate genomic tools for resilient dairy. Specifically, we describe the current state of the RDGP database, data collection protocols in each country, and the strategies used for managing the shared data. As of February 2022, the database contains 1,289,593 DMI records from 12,687 cows and 17,403 CH4 records from 3,093 cows and continues to grow as countries upload new data over the coming years. No strong genomic differentiation between the populations was identified in this study, which may be beneficial for eventual across-country genomic predictions. Moreover, our results reinforce the need to account for the heterogeneity in the DMI and CH4 phenotypes in genomic analysis.

Estimation of genetic parameters for feed efficiency traits using random regression models in dairy cattle.

Feed efficiency has become an increasingly important research topic in recent years. As feed costs rise and the environmental impacts of agriculture become more apparent, improving the efficiency with which dairy cows convert feed to milk is increasingly important. However, feed intake is expensive to measure accurately on large populations, making the inclusion of this trait in breeding programs difficult. Understanding how the genetic parameters of feed efficiency and traits related to feed efficiency vary throughout the lactation period is valuable to gain understanding into the genetic nature of feed efficiency. This study used 121,226 dry matter intake (DMI) records, 120,500 energy-corrected milk (ECM) records, and 98,975 metabolic body weight (MBW) records, collected on 7,440 first-lactation Holstein cows from 6 countries (Canada, Denmark, Germany, Spain, Switzerland, and the United States), from January 2003 to February 2022. Genetic parameters were estimated using a multiple-trait random regression model with a fourth-order Legendre polynomial for all traits. Weekly phenotypes for DMI were re-parameterized using linear regressions of DMI on ECM and MBW, creating a measure of feed efficiency that was genetically corrected for ECM and MBW, referred to as genomic residual feed intake (gRFI). Heritability (SE) estimates varied from 0.15 (0.03) to 0.29 (0.02) for DMI, 0.24 (0.01) to 0.29 (0.03) for ECM, 0.55 (0.03) to 0.83 (0.05) for MBW, and 0.12 (0.03) to 0.22 (0.06) for gRFI. In general, heritability estimates were lower in the first stage of lactation compared with the later stages of lactation. Additive genetic correlations between weeks of lactation varied, with stronger correlations between weeks of lactation that were close together. The results of this study contribute to a better understanding of the change in genetic parameters across the first lactation, providing insight into potential selection strategies to include feed efficiency in breeding programs.

Hydroponic barley supplementation fed with high protein diets improves the production performance of lactating dairy cows.

The study investigated the effects of dietary protein level and the inclusion of hydroponic barley sprouts (HB) on lactation performance, blood biochemistry and N use efficiency in mid-lactation dairy cows. Treatments were arranged in a 2 × 2 factorial design with 2 crude protein (CP) levels [16.8% and 15.5% of dry matter (DM)], with HB (4.8% of DM, replacing 4.3% of alfalfa hay and 0.5% of distillers dried grains with solubles (DDGS)) or without HB. Forty-eight multiparous Holstein dairy cows (146 ± 15 d in milk, 40 ± 5 kg/d of milk) were randomly allocated to 1 of 4 diets: high protein diet (16.8% CP, HP), HP with HB (HP+HB), low protein diet (15.5% CP, LP), or LP with HB (LP+HB). An interaction between CP × HB on dry matter intake (DMI) was detected, with DMI being unaffected by HB inclusion in cows fed the high CP diets, but was lower in cows fed HB when the low CP diet was fed. A CP × HB interaction was also observed on milk and milk protein yield, which was higher in cows fed HB with HP, but not LP. Inclusion of HB also tended to reduce milk fat content, and feeding HP resulted in a higher milk protein and milk urea N content, but lower milk lactose content. Feed efficiency was increased by feeding HP or HB diets, whereas N efficiency was higher for cows fed LP or HB diets. There was an interaction on the apparent total-tract digestibility of DM and CP, which was higher when HB was fed along with HP, but reduced when fed with LP, whereas the digestibility of ADF was increased by feeding low protein diets. In conclusion, feeding a low protein diet had no adverse effect on cow performance, while feeding HB improved milk and milk component yield, and N efficiency when fed with a high CP diet, but compromised cow performance with a low CP diet.

Interaction between residual feed intake and thermal environment on performance, nitrogen balance, ingestive behavior and carcass yield of dorper lambs.

Residual feed intake (RFI) is a nutritional variable used in genetic improvement programs, the relationship between the environment and the availability of energy and protein in the diet has not yet been explored. Thus, the aim was to evaluate interactions between RFI and thermal environment on performance, nitrogen balance, ingestive behavior and carcass yield of Dorper lambs receiving diets containing different concentrate levels. Dorper lambs (male, n = 64, 17.83 ± 2.43 kg and 110 ± 10 days of age) were confined individually for 40 days for RFI classification. Lambs were separated into positive RFI (n = 30) and negative RFI (n = 30) and remained confined for another 60 days. The animals were distributed in a randomized block design, with a 2 × 2 × 3 factorial scheme, with 2 confinement environments (full sun or shade), 2 groups of feed efficiency (RFI positive or RFI negative) and three diets containing different concentrate levels (30, 45 and 60%), with 5 replications in each treatment. Isolated effects of concentrate level were observed for dry matter intake and digestibility, feeding, rumination, idle and chewing times, feeding efficiency, ingested, excreted and absorbed nitrogen, and on cooling losses, hot and cold carcass yield (P < 0.05). There was an effect of environment × concentrate interaction on performance, retained nitrogen and nitrogen balance (P < 0.05). There was an effect of RFI × environment interaction on the dry matter rumination efficiency, hot and cold carcass weight (P < 0.05). Under experimental conditions, RFI did not influence the productive performance of Dorper lambs. Interactions between environment and diet indicate better performance for Dorper lamb confined in the shade and receiving a higher proportion of concentrate. Animals with negative RFI show better performance and carcass weight when confined in shade, while animals with positive RFI showed better responses to these variables when confined in full sun.

Substitution of soybean meal for yellow mealworm meal in the diet of slow-growing chickens provides comparable carcass traits and meat quality.

1. This study investigated the effects of incorporating yellow mealworm (Tenebrio molitor) larval meal as a partial and/or complete substitute for soybean meal on carcass and meat quality in slow-growing chickens.2. A total of 256 one-day-old male broilers were randomly allocated to 1 of 32 experimental units distributed among four treatments (n = 8): the control treatment (C), where soybean (SB) meal was the protein source, and three experimental treatments, in which SB meal was replaced by Tenebrio molitor (TM) larval meal at levels of 50% (T1), 75% (T2) and 100% (T3), respectively. Three different feed phases (1-29; 29-57 and 57-92 d of age) were used for each treatment. All chickens were slaughtered at 92 d of age, with eight animals per treatment randomly selected to assess carcass and meat quality. Near-infrared reflectance spectroscopy (NIR) was used to classify meat quality.3. Carcass traits were not significantly different between treatments, except for head and thigh weight, which were higher in the control group (p < 0.01). In terms of physicochemical characteristics, treatment T2 showed less yellowness (p < 0.05), while water and cooking losses were lower in treatments T1 and T2 (p < 0.01). Meat from both T1 and T2 groups had lower shear forces (p < 0.01), higher moisture content (p < 0.01) and less protein (p < 0.05) compared to treatments C andT3. Birds fed T3 had the highest meat ash content (p < 0.01). Chickens consuming TM had higher monounsaturated fatty acid (MUFA) levels and lower polyunsaturated fatty acid (PUFA) and n-6 acidsPUFA (p < 0.01).4. Substitution of SB with TM is a protein alternative for slow-growing chickens that supports carcass and meat quality comparable to those fed a conventional diet.

Impact of corn silage or corn silage plus protein supplementation on the ingestive and rumination behaviours, ruminal fermentation characteristics and efficiency of grazing dairy cows.

This study's objective was to compare two options of pasture supplementation: corn silage (CS) alone or corn silage mixed with protein concentrate. The experiment was conducted with 18 lactating Holstein cows in mid-lactation in a crossover design that included three treatments and three data collection periods. All cows had access to pasture for 17 h/day with an average herbage allowance of 16 kg dry matter (DM)/cow/day and were offered in-barn corn silage, corn silage mixed with protein concentrate, or no supplementation. Cows were equipped with pH sensors residing in the reticulum and, during the 7-day data collection periods, with a jaw movement recorder. Nonsupplemented cows produced 21.3 kg energy-corrected milk (ECM) and ate 13.3 kg DM herbage at pasture. Cows supplemented with corn silage and corn silage plus protein produced 2.5 and 4.5 kg/day more ECM, respectively, consumed 3.4 and 3.3 kg/day more DM in total, respectively, ate for a shorter period of time, and ruminated longer than their nonsupplemented peers. Supplemented cows were almost able to cover their energy requirements and mobilised less body mass in contrast to the nonsupplemented cows. Cows offered corn silage plus protein showed increased ECM production, increased milk urea content and lower nitrogen use efficiency (NUE) compared to cows supplemented with corn silage only. Nonsupplemented dairy cows had the highest milk urea content and performed worst in terms of NUE. The best feed conversion efficiency resulted from the nonsupplemented dairy cows and those supplemented with corn silage plus protein. In nonsupplemented cows, the high feed conversion efficiency seemed to be due to the increased mobilisation of body mass. As a result of the starch-rich supplementations, the ruminal acetic:propionic acid ratio became smaller, and the proportions of n-butyric acid increased. The mean reticular pH values did not substantially vary across the three feeding treatments. For the choice of a supplementation option, herbage allowance and cost of supplement will have to be considered, but aspects of feed-food competition as well as animal welfare should not be ignored.