Objectives of this study were to determine if variation in energy expenditures contributed to differences in feed efficiency between low and high RFI steers. Nine steers with the lowest and highest residual feed intakes (RFI) were selected from 169 Braunvieh-sired crossbred steers that were individually fed a pelleted roughage-based diet for 77 d. Following the RFI measurement period, heat production (HP) measurements were obtained using indirect calorimetry while steers were fed the same roughage diet (RD) and on a high-concentrate diet (CD). Linear regression analyses of log HP or retained energy on ME intake were used to determine energy partitioning. Motion and lying activity were measured concurrently with HP on the RD and CD. During the RFI measurement period, low RFI steers had lower (P < 0.01) RFI (-1.7 vs. 1.6 ± 0.17 kg/d), DMI (7.7 vs. 10.2 ± 0.42 kg/d) and feed:gain ratio (F:G; 7.2 vs. 10.6 ± 0.60), but similar final BW and ADG compared to high RFI steers. However, there were smaller differences in DMI (8.4 vs. 9.7 ± 0.38 kg/d; P < 0.05; 7.56 vs. 8.16 ± 0.31; P = 0.19) and F:G (10.0 vs. 10.9 ± 0.40; P = 0.36; 6.5 vs. 7.5 ± 0.30; P < 0.05) between low and high RFI steers, on the RD and CD, respectively. ME for maintenance (MEm; kg .75 d–1) and the partial efficiencies of ME used for maintenance and gain were similar for low and high RFI steers. Likewise, no differences were found in fasting HP or fed HP. Motion activity was lower (P < 0.05) for low RFI steers compared to high RFI steers during fasting HP. Covariate analysis of HP at the same activity level yielded similar results. At slaughter, weights of lung and trachea (P < 0.05), spleen (P < 0.05) and adrenal gland (P = 0.07) were higher for low RFI cattle. The lack of differences in energy partitioning between divergent RFI steers may have been the result of alterations in feeding behavior or stress imposed by adapting steers to calorimetry chambers.

With feed costs representing on average 65% of the total cost of production improvements in feed efficiency could have a major impact on the beef industry. Postweaning performance and feed efficiency data were collected on 114 heifers born on the University of Arizona's V bar V Ranch. Residual feed intake (RFI) was significantly correlated with dry matter intake (DMI) (r = 0.46) and G:F (r = -0.43), while G:F was moderately correlated with initial age (r = -0.54), initial body weight (r = -0.40), and average daily gain (ADG) (r = 0.68). Residual gain (RG) was moderately correlated with RFI (r = -0.41) and highly correlated with ADG (0.62) and G:F (0.73). In addition, RG was significantly correlated (r = -0.21) with initial weight suggesting that selection for RG could lead to increased cow mature size. Heifers were sorted into three breed categories: Hereford, Hereford cross, and Wagyu cross and breed effect on performance and feed efficiency traits were analyzed. Significant differences in DMI, FCR, and RG were noted, but likely due to significant differences in age at the time of testing. RFI was not significantly different between breed groups, suggesting that RFI is less influenced by animal age than other measures of feed efficiency. In addition, sires of study heifers with 5 or more progeny were selected and progeny performance and feed efficiency traits were compared between sires. No significant differences in ADG, RFI, FCR, or RG were noted between sire progeny. This was likely due to an insufficient number of progeny used in the trial. Further research and an increased number of animals used may uncover significant impacts of sire on RFI.

The objectives of this study were to evaluate the effects of residual feed intake (RFI) classification on performance, feed efficiency, feeding behavior and carcass traits, and to determine the relative importance of individual performance and carcass measurements on between-animal variation in net revenue of feedlot steers. Performance, feed intake and feeding behavior traits were measured in 508 Angus-based composite steers, using the GrowSafe feed-intake measurement system, while fed a high-grain diet for 70 days. Residual feed intake (RFI) was computed as actual minus expected dry matter intake (DMI) derived from regression of DMI on average daily gain (ADG) and mid-test BW0.75, and steers classified into low (n = 150), medium (n = 200) and high (n = 158) RFI groups. Following the feed-intake measurement periods, steers were fed the same diet in group pens and harvested at an average backfat thickness of 1.14 cm. Net revenue (NR) was calculated as carcass value minus feeder calf, yardage, and feed costs using 3-year average prices. Feed cost was based on actual feed consumed during the feed-intake measurement periods, and model-predicted intake adjusted for RFI during the group-feeding periods. Steers with low RFI had $48/hd lower (P < 0.0001) feed cost, $16/hd numerically higher (P = 0.29) carcass value, and $62/hd more favorable (P < 0.0001) net revenue compared to their high-RFI counterparts. Net revenue was correlated with carcass weight, marbling score, yield grade, DMI, ADG, RFI and G:F ratio where animals that consumed more feed, had higher rates of gain and were more efficient had more favorable net returns. Models predicting net revenue from performance, carcass quality, and feed efficiency traits accounted for 77% of the between-animal variation in NR. In the base model, that included all traits performance, carcass quality and feed efficiency traits explained 28, 14 and 35%, respectively, of the variation in NR. Results from this study indicate that between-animal variation in net revenue was impacted to a great extent by performance and feed efficiency, rather than carcass quality traits, in Angus-based composite steers based on average 3-year pricing scenarios.

Feed intake is a key factor affecting pig performance; thus, the objective of these studies was to assess a variety of factors that could potentially affect intake in pigs in different production stages. Studies were conducted to determine the effects of flavor and diet complexity, Appetein™ (an alternative protein source), and graded levels of salt on swine feed intake and feed preference. Two newly developed flavors were used in nursery pig diets. The use of the two flavors did not increase feed intake (P > 0.05). Nursery pigs actually showed a preference for the control diet. Complex diet formulation does increase feed intake (P < 0.03) in nursery pigs when diets are not over-formulated. When flavor was added to lactation diets sow feed intake did not change compared to the control. The flavor did not affect litter performance (P > 0.05). When Appetein™ was added to lactation diets at 0.5%, pig weight and litter weight were numerically greater for the sows fed Appetein™ but not significantly so. Appetein™ did not affect feed intake. When nursery pigs were fed graded levels of salt (0.1, 0.5, and 0.8%) feed intake increased (P < 0.01) as salt level increased. Nursery pigs also preferred (P < 0.05) 0.8% salt over other levels the first two weeks after weaning when given a choice among diets.

The objectives of this study were to characterize residual feed intake (RFI) in growing bulls and heifers and in mid-gestation females to examine relationships with performance, body composition, feeding behavior, digestibility (DMD) and heart rate (HR) and evaluate the impact of RFI on bull fertility and cow forage utilization. Additionally, use of the n-alkane method to predict individual animal variations in intake was investigated. To accomplish these objectives, multiple RFI studies were conducted. In all studies RFI was computed as the difference between actual and expected DMI from linear regression of DMI on mid-test metabolic BW and ADG. To evaluate phenotypic relationships between feed efficiency, scrotal circumference (SC) and semen-quality an experiment was conducted with yearling bulls (N=204). Residual feed intake was not correlated with BW and ADG, but was positively associated with 12th-rib back fat (BF) such that the more efficient bulls were leaner. Bulls with low RFI had similar SC and progressive motility of sperm compared to high-RFI bulls. However percent normal sperm were weakly associated with RFI in a negative manner. To examine phenotypic relationships between heifer postweaning RFI, and performance, efficiency, HR, and DMD of mid-gestation cows, RFI was measured in growing Bonsmara heifers (N=175). Forty-eight heifers with divergent RFI were retained for breeding. Subsequently, intake, performance and feeding behavior was measured on mid-gestation females. Pregnant females classified as having low postweaning RFI continued to consume 22% less feed, spent 25% less time eating, and had 7% lower HR while maintaining similar BW, ADG and body composition compared to high RFI females. A moderate association between RFI in growing heifers and subsequent efficiency of forage utilization in pregnant cows was found. Growing heifers identified as efficient had greater DMD, however DMD in mature cows was similar between RFI groups. The n-alkane method of predicting intake detected differences in intake between divergent RFI groups in mid-gestation females. Results from this study indicate that inclusion of RFI as a component of a multi-trait selection program will improve feed efficiency of growing animals and mid-gestation females with minimal impacts on growth, body composition, and fertility traits.

Residual feed intake (RFI) is a recognized measure of biological efficiency in beef cattle. However, RFI determination is expensive, time consuming and not well studied in animals fed forage-based diets. The objectives of this experiment were to investigate infrared thermography (IRT) as method for determining RFI ranking in yearling beef bulls, and to evaluate the effect of diet type on RFI repeatability in consecutive feeding periods. No significant correlations (P > 0.05) were observed between eye or cheek surface temperatures measured using handheld or within-pen stationary infrared camera systems with RFI. Reranking was observed for RFI in all diet treatments, however significant repeatability estimates occurred for the forage and grain diet treatments (r=0.58 and 0.64 respectively; P < 0.01) but not the diet switch treatment (r=0.24; P > 0.05). Extreme cold temperatures experienced in Western Canada influence IRT measurements and energy partitioning, indicating the need for standardized performance testing procedures. / February 2016

Melhorar o peso dos leitões ao nascimento e consequentemente ao desmame é um os principais desafios da suinocultura moderna, uma vez que ao serem melhoradas para produzir uma quantidade maior de leitões ao nascimento, as matrizes hiperprolíficas acabaram desenvolvendo uma característica indesejável, que é a produção de leitegadas com maior desuniformidade, e um número elevado de leitões com baixo peso ao nascimento. O objetivo do presente estudo foi avaliar a variação do nível de fibra bruta na dieta fornecida dos 74 aos 114 dias de gestação, sobre a digestibilidade dos nutrientes e da energia na gestação, desempenho produtivo e respostas sanguíneas das fêmeas nos períodos de lactação e gestação. Foram utilizadas 33 porcas distribuídas em um delineamento experimental inteiramente casualizado. Os níveis de fibra bruta (FB) nos tratamentos (T) foram: 3,3%, 7,0% e 10,1%. Para aumentar o nível de fibra a quirera de arroz e o farelo de soja foram substituídos parcialmente por farelo de arroz desengordurado e casca de soja. O consumo diário de nutrientes e energia foi similar para todo o período de gestação estudado, diferindo apenas o volume de ração consumida, que para o período dos 74 aos 90 dias de gestação foi de 2,10, 2,21 e 2,40 kg/dia, e para 91 a 111 dias de 2,47, 2,65 e 2,85 kg/dia para T1, T2 e T3, respectivamente. Os dados foram submetidos à análise de variância pelo procedimento MIXED do SAS, e as médias comparadas pelo teste de Fisher (LSD). Análise de regressão foi realizada, utilizando-se a regressão linear ou quadrática conforme o melhor ajuste. Na gestação, o aumento de fibra da dieta proporcionou um decréscimo linear (P<0,05) na energia digestível (ED) e no coeficiente de digestibilidade aparente (CDA) (%) da matéria seca (MS), energia bruta (EB), proteína bruta (PB), carboidratos não fibrosos (CNF) e matéria orgânica (MO). Os níveis sanguíneos, na gestação, de proteína total e globulinas apresentaram um efeito quadrático (P<0,05) ao nível de fibra da dieta, já o colesterol apresentou um efeito linear crescente (P<0,05). Aos 105 dias de gestação e aos 4 dias de lactação os níveis de creatinina (P<0,05) foram maiores nas fêmeas que consumiram 10,1% de FB. O desempenho produtivo e reprodutivo das fêmeas na gestação e lactação, e o peso dos leitões ao nascimento não foram influenciados (P>0,05) pelos T, no entanto, o ganho médio diário das leitegadas apresentou um efeito linear crescente (P<0,05) com o aumento da FB da dieta. Concluindo, o aumento da fibra na dieta causou diminuição na digestibilidade dos nutrientes e energia, sem, contudo afetar o desempenho das matrizes na gestação, lactação e dos leitões ao parto. O uso da fibra na gestação melhorou o ganho de peso dos leitões na lactação. / Improving the weight of piglets at birth and consequently at weaning is one the key challenges of modern pig industry, since by being improved to produce greater amount of piglets at birth, hyperprolific matrices end up by developing an undesirable characteristic, which is the production of littermates with lack of uniformity and high number of piglets with low birth weight. The aim of this study was to evaluate the effect of the variation in crude fiber level in the diet provided at 74 to 114 days of gestation on the digestibility of nutrients and energy in pregnancy, production performance and blood responses of sows in periods of lactation and pregnancy. Thirty-three sows were distributed in a completely randomized design. Crude fiber levels (CF) in treatments (T) were 3.3%, 7.0% and 10.1%. To increase the fiber level, broken rice and soybean meal were partially replaced by defatted rice bran and soybean hulls. The daily intake of nutrients and energy was similar for the entire pregnancy period, differing only in the amount of diet consumed, and for the period from 74 to 90 days of pregnancy, levels were 2.10, 2.21 and 2.40 kg/day and from 91 to 111 days of 2.47, 2.65 and 2.85 kg/day for T1, T2 and T3, respectively. The data were submitted to analysis of variance using the SAS MIXED procedure, and means were compared using the Fisher test (LSD ). Regression analysis was performed using the linear or quadratic regression according better fit. During pregnancy, the increase in dietary fiber provided a linear decrease (P <0.05) in digestible energy (DE) and apparent digestibility coefficient (ADC) (%) of dry matter (DM), crude energy (CE), crude protein (CP), non-fiber carbohydrates (NFC) and organic matter (OM). Blood globulins and total protein levels in pregnancy showed a quadratic effect (P <0.05) to the dietary fiber level, but cholesterol showed an increasing linear effect (P <0.05). At 105 days of pregnancy and after 4 days of lactation, creatinine levels (P <0.05) were higher in females who consumed 10.1% CF. The productive and reproductive performance of females during pregnancy and lactation, and the weight of piglets at birth were not affected (P> 0.05) by T; however, the average daily gain of piglets showed a linear increase (P <0.05) with increasing CF in the diet. In conclusion, increasing fiber in the diet caused a decrease in the digestibility of nutrients and energy, without; however, affecting the performance of matrices during pregnancy, lactation and weight of piglets at birth. The use of fiber during pregnancy improved the weight gain of piglets during lactation.

Melhorar o peso dos leitões ao nascimento e consequentemente ao desmame é um os principais desafios da suinocultura moderna, uma vez que ao serem melhoradas para produzir uma quantidade maior de leitões ao nascimento, as matrizes hiperprolíficas acabaram desenvolvendo uma característica indesejável, que é a produção de leitegadas com maior desuniformidade, e um número elevado de leitões com baixo peso ao nascimento. O objetivo do presente estudo foi avaliar a variação do nível de fibra bruta na dieta fornecida dos 74 aos 114 dias de gestação, sobre a digestibilidade dos nutrientes e da energia na gestação, desempenho produtivo e respostas sanguíneas das fêmeas nos períodos de lactação e gestação. Foram utilizadas 33 porcas distribuídas em um delineamento experimental inteiramente casualizado. Os níveis de fibra bruta (FB) nos tratamentos (T) foram: 3,3%, 7,0% e 10,1%. Para aumentar o nível de fibra a quirera de arroz e o farelo de soja foram substituídos parcialmente por farelo de arroz desengordurado e casca de soja. O consumo diário de nutrientes e energia foi similar para todo o período de gestação estudado, diferindo apenas o volume de ração consumida, que para o período dos 74 aos 90 dias de gestação foi de 2,10, 2,21 e 2,40 kg/dia, e para 91 a 111 dias de 2,47, 2,65 e 2,85 kg/dia para T1, T2 e T3, respectivamente. Os dados foram submetidos à análise de variância pelo procedimento MIXED do SAS, e as médias comparadas pelo teste de Fisher (LSD). Análise de regressão foi realizada, utilizando-se a regressão linear ou quadrática conforme o melhor ajuste. Na gestação, o aumento de fibra da dieta proporcionou um decréscimo linear (P<0,05) na energia digestível (ED) e no coeficiente de digestibilidade aparente (CDA) (%) da matéria seca (MS), energia bruta (EB), proteína bruta (PB), carboidratos não fibrosos (CNF) e matéria orgânica (MO). Os níveis sanguíneos, na gestação, de proteína total e globulinas apresentaram um efeito quadrático (P<0,05) ao nível de fibra da dieta, já o colesterol apresentou um efeito linear crescente (P<0,05). Aos 105 dias de gestação e aos 4 dias de lactação os níveis de creatinina (P<0,05) foram maiores nas fêmeas que consumiram 10,1% de FB. O desempenho produtivo e reprodutivo das fêmeas na gestação e lactação, e o peso dos leitões ao nascimento não foram influenciados (P>0,05) pelos T, no entanto, o ganho médio diário das leitegadas apresentou um efeito linear crescente (P<0,05) com o aumento da FB da dieta. Concluindo, o aumento da fibra na dieta causou diminuição na digestibilidade dos nutrientes e energia, sem, contudo afetar o desempenho das matrizes na gestação, lactação e dos leitões ao parto. O uso da fibra na gestação melhorou o ganho de peso dos leitões na lactação. / Improving the weight of piglets at birth and consequently at weaning is one the key challenges of modern pig industry, since by being improved to produce greater amount of piglets at birth, hyperprolific matrices end up by developing an undesirable characteristic, which is the production of littermates with lack of uniformity and high number of piglets with low birth weight. The aim of this study was to evaluate the effect of the variation in crude fiber level in the diet provided at 74 to 114 days of gestation on the digestibility of nutrients and energy in pregnancy, production performance and blood responses of sows in periods of lactation and pregnancy. Thirty-three sows were distributed in a completely randomized design. Crude fiber levels (CF) in treatments (T) were 3.3%, 7.0% and 10.1%. To increase the fiber level, broken rice and soybean meal were partially replaced by defatted rice bran and soybean hulls. The daily intake of nutrients and energy was similar for the entire pregnancy period, differing only in the amount of diet consumed, and for the period from 74 to 90 days of pregnancy, levels were 2.10, 2.21 and 2.40 kg/day and from 91 to 111 days of 2.47, 2.65 and 2.85 kg/day for T1, T2 and T3, respectively. The data were submitted to analysis of variance using the SAS MIXED procedure, and means were compared using the Fisher test (LSD ). Regression analysis was performed using the linear or quadratic regression according better fit. During pregnancy, the increase in dietary fiber provided a linear decrease (P <0.05) in digestible energy (DE) and apparent digestibility coefficient (ADC) (%) of dry matter (DM), crude energy (CE), crude protein (CP), non-fiber carbohydrates (NFC) and organic matter (OM). Blood globulins and total protein levels in pregnancy showed a quadratic effect (P <0.05) to the dietary fiber level, but cholesterol showed an increasing linear effect (P <0.05). At 105 days of pregnancy and after 4 days of lactation, creatinine levels (P <0.05) were higher in females who consumed 10.1% CF. The productive and reproductive performance of females during pregnancy and lactation, and the weight of piglets at birth were not affected (P> 0.05) by T; however, the average daily gain of piglets showed a linear increase (P <0.05) with increasing CF in the diet. In conclusion, increasing fiber in the diet caused a decrease in the digestibility of nutrients and energy, without; however, affecting the performance of matrices during pregnancy, lactation and weight of piglets at birth. The use of fiber during pregnancy improved the weight gain of piglets during lactation.

No description available.

O objetivo dessa pesquisa foi avaliar os parâmetros genéticos e correlações das medidas de ingestão e eficiência alimentar com desempenho e características de carcaça, além de realizar o estudo de associação de amplo genoma (GWAS) para ingestão de matéria seca (IMS), consumo alimentar residual (CAR) e ganho de peso (GMD) em bovinos da raça Nelore (Bos indicus). Foram utilizados dados de 1.058 animais com fenótipo para IMS, taxa de conversão alimentar (CA), CAR, ganho de peso residual (GPR), consumo e ganho residuais (CGR), ganho de peso diário (GMD) e características de carcaça. Os parâmetros genéticos da IMS, CA, CAR, GPR e CGR e suas as correlações com GMD e características de carcaça foram estimados utilizando abordagem bayesiana. Quatro marcadores do tipo SNP (Single Nucleotide Polymorphism), localizados em genes relacionados ao controle de apetite (NPY e PDE3B) e transporte iônico (TRPM3 e ITPR1), foram associados com o desempenho, ingestão e medidas de eficiência alimentar. Adicionalmente, os animais foram genotipados em dois chips distintos (Illumina Bovine HD e Illumina BovineSNP50) e as informações genotípicas foram combinadas por meio de estudo de imputação. As centenas de milhares de SNPs foram utilizadas para o GWAS da IMS, CAR e GMD pelo teste de associação GRAMMAR-Gamma. A herdabilidade da IMS, CAR e CGR foi de 0,40, 0,38 e 0,54, respectivamente. Não foram encontradas associações nos SNPs localizados nos genes TRPM3, NPY e ITPR1, no entanto, o SNP no gene PDE3B foi associados significativamente (P&le;0,05) com IMS, CAR e CGR. Os SNPs mais associados com a IMS e CAR, no GWAS, estão localizados nos cromossomos 4, 8, 14 e 21 em regiões genômicas relacionadas com transporte iônico e regulação da ingestão. O GWAS para o GMD apontou os cromossomos 3, 6 e 10 como os que continham os marcadores com maior associação. A ingestão e eficiência alimentar são passíveis de seleção genética, principalmente o CGR. O gene PDE3B deve ser melhor estudado pois, aparenta ter relação com esses fenótipos. Por fim, esse trabalho apontou regiões genômicas, por meio de associação de amplo genoma, relacionadas com a IMS, CAR e GMD, acredita-se ser o primeiro estudo desse tipo para esses fenótipos em animais da raça Nelore. / The aim of this study was to evaluate the genetic parameters and correlations of intake and feed efficiency with performance and carcass traits, and perform the genome-wide association study (GWAS) for dry matter intake (DMI), residual feed intake (RFI) and average daily gain (ADG) in Nelore cattle (Bos indicus). Data from 1,058 animals phenotyped for DMI, feed conversion ratio (FCR), RFI, residual body weight gain (RG), residual intake and body weight gain (RIG), average daily gain (ADG) and carcass traits were used. Genetic parameters of DMI, FCR, RFI, RG and RIG and their correlations with ADG and carcass traits were estimated using Bayesian approach. Four SNPs (Single Nucleotide Polymorphism), located in genes related to appetite control (NPY and PDE3B) and ion transport (TRPM3 and ITPR1), were associated with performance, intake and feed efficiency traits. Additionally, the animals were genotyped in two different chips (Illumina Bovine HD and Illumina BovineSNP50) and genotypic information were combined by imputation. The hundreds of thousands of SNPs were used for GWAS of DMI, RFI and ADG by GRAMMAR-Gamma association test. The heritability of DMI, RFI and RIG was 0.40, 0.38 and 0.54, respectively. No associations were found in SNPs in genes TRPM3, NPY and ITPR1, however, the SNP in PDE3B gene was significantly associated (P&le;0.05) with DMI, RFI and RIG. The SNPs most associated with DMI and RFI, in GWAS, are located on chromosomes 4, 8, 14 and 21 in genomic regions associated with ion transport and appetite regulation. The GWAS pointed chromosomes 3, 6 and 10 as those containing more associated markers for ADG. Feed intake and feed efficiency are amenable to genetic selection, especially the RIG. The PDE3B gene should be further studied thus appears to be related to these phenotypes. Finally, this work shows genomic regions by genome-wide association, related to DMI, RFI and ADG, believed to be the first study of its kind for these phenotypes in Nellore cattle.