Effects of energy-protein supplementation frequency on performance of primiparous grazing beef cows during pre and postpartum.

OBJECTIVE: Twenty-four pregnant Nellore primiparous grazing cows were used to evaluate the effects of energy-protein supplementation and supplementation frequency during pre (105 d before calving) and postpartum (105 d after calving) on performance and metabolic characteristics. METHODS: Experimental treatments consisted of a control (no supplementation), daily supplementation (1.5 kg/d of concentrate/animal) and infrequent supplementation (4.5 kg of concentrate/animal every three days). During the pre and postpartum periods, concentrations of blood metabolites and animal performance were evaluated. Ureagenesis and energy metabolism markers were evaluated at prepartum period. RESULTS: Supplementation frequency did not alter (p>0.10) body weight (BW), average daily gain (ADG), and carcass traits during pre and postpartum. The BW (p = 0.079), adjusted BW at day of parturition (p = 0.078), and ADG (p = 0.074) were greater for supplemented cows during the prepartum. The body condition score (BCS; p = 0.251), and carcass traits (p>0.10) were not affected by supplementation during prepartum. On postpartum, supplementation did not affect animal performance and carcass traits (p>0.10). The dry mater intake was not affected (p>0.10) by supplementation and supplementation frequency throughout the experimental period. Daily supplemented animals had greater (p<0.001) glucose levels than animals supplemented every three days. Supplementation and supplementation frequency did not alter (p>0.10) the levels of blood metabolites, neither the abundance of ureagenesis nor energy metabolism markers. CONCLUSION: In summary, our data show that the reduction of supplementation frequency does not cause negative impacts on performance and metabolic characteristics of primiparous grazing cows during the prepartum.

Nutritional strategies for heifers under grazing system: productive and nutritional performance, metabolic profile and ovarian activity.

The objective of this study was to evaluate the effects of nutritional strategies on productive and nutritional performance, metabolic profile, and ovarian activity in heifers under grazing in the tropics in Brazil. Forty Nellore heifers averaging 8.5 ± 0.06 months and 248.6 ± 3.3 kg body weight (BW) were distributed in a completely randomized 2 × 2 factorial design with four treatments and ten replicates. The evaluated strategies consisted of different amounts of energetic-protein supplement: (1) 4 g/kg of BW of supplement in the pre-weaning and post-weaning; (2) 4 g/kg of BW of supplement pre-weaning and 6 g/kg in the post-weaning; (3) 6 g/kg of BW of supplement in the pre-weaning and 4 g/kg of BW in the post-weaning and; (4) 6 g/kg of BW of supplement in the pre-weaning and post-weaning. Crude protein (CP) and organic matter (OM) intake were increased (P < 0.05) by increasing the amounts of supplement in the post-weaning. Additionally, increasing supplement amounts in the post-weaning increased the digestibility of OM and CP (P < 0.05). Means insulin and glucose concentrations were greater (P < 0.05) for heifers that received higher amounts of supplement in the post-weaning. Average daily gain and fat thickness in the rump were increased (P < 0.05) by increasing supplement amounts in the post-weaning. Amounts of supplement did not influence the body growth of heifers. However, follicular number, diameter, and progesterone concentration were greater (P < 0.05) for heifers that received higher amounts of supplement in the post-weaning. In summary, increasing supplement amounts in the post-weaning improve the performance, energy and metabolic status, and ovarian activity in beef heifers under grazing in the tropics. Due to higher intake of supplement, the heifers receiving 6 g/kg of BW post-weaning had greater responses, independently of the supplement amount received pre-weaning.

Nutritional planning for Nellore heifers post-weaning to conception at 15 months of age: performance and nutritional, metabolic, and reproductive responses.

The objective of this study was to evaluate the effects of strategic supplementation in the dry period and dry/rainy transition period on the performance and nutritional, metabolic, and reproductive responses of Nellore heifers grazing Urochloa decumbens. Forty-eight Nellore heifers with age and body weight (BW) of eight months and 235 ± 3.3 kg, respectively, were used. The experimental design was a completely randomized design, with four treatments, all with 12 replications. The evaluated strategies were as follows: low supplementation (LOHI; 0.2% of BW/heifer/day) in the first 90 days and high supplementation (0.6% of BW/heifer/day) in the 90 days thereafter; average supplementation (AVER) with 0.4% of BW/heifer/day for 180 days; high supplementation (HILO; 0.6% of BW/heifer/day) in the first 90 days and low supplementation (0.2% of BW/heifer/day) in the 90 days thereafter; only mineral mix (MM) ad libitum during the 180 days. Data were evaluated using orthogonal contrasts. Supplementation improved the performance of the animals during of dry period (P < 0.05) and dry/rainy transition period (P < 0.05). Supplemented animals had higher longissimus muscle area (LMA) and subcutaneous fat thickness (SFT) at the end of the experiment (P < 0.05). Multiple supplementation increased intake of dry matter (DM), organic matter (OM), and crude protein (CP) in kg/day throughout the experiment. The supplementation increased the digestibility of DM, OM, CP, apNDF, and TDN (P < 0.05). Serum urea nitrogen (SUN), glucose (GLUC), insulin (INS), and progesterone (PROG) were higher in supplemented heifers (P < 0.05). Supplementation reduced the concentrations of non-esterified fatty acids (NEFA) (P < 0.05) and increased conception rate (P < 0.05). In summary, the supplementation strategies adopted in this study improve the performance, metabolic status, and carcass traits of heifers under grazing, allowing an improvement in the conception rate of 15-month-old Nellore heifers.

Evaluation of supplementation plans for suckling beef calves managed on tropical pasture / Avaliação de planos de suplementação para bezerros de corte lactentes manejados em pasto tropical

This study assessed the effects of different amounts of supplement on the productive performance, nutrional caracteristics and behaviour of suckling beef calves, as well as on the productive performance of their dams on tropical pastures. Forty-four male Nellore beef calves with an average age of 120 days and an initial average body weight (BW) of 145±3.7 kg and their respective dams, with an average BW of 449±6.9 kg, were used. The amounts of supplement evaluated were as follows: 0 = calves received only mineral mixture ad libitum; 3, 6, and 9 = calves received 3, 6, or 9 g kg-1 BW of supplement, respectively, containing 250 g CP kg-1 (as-fed). The experimental design was completely randomized. A positive linear effect (P < 0.01) was observed in the intakes of dry matter and organic matter, and a cubic effect (P < 0.07) was observed for the intake of neutral detergent fiber corrected for ash and protein. There was quadratic effect (P < 0.06) for total digestibility of neutral detergent fiber. A cubic effect (P < 0.01) was observed for the calves performance. However, the calves supplementation did not affect the milk yield and performance (P ≥ 0.21) of their dams. The supplementation decreased grazing time (P < 0.01) but did not influence suckling time (P ≥ 0.59). It is recommended supplying of supplement containing 250 g CP kg-1 (as-fed) in amount 6 g kg-1 BW to suckling beef calves managed in tropical pasture. Supplementation of suckling beef calves increases the intake of dry matter, decreases grazing time and forage intake. However, it does not affect the suckling time and productive performance of their dams.(AU)

Este estudo avaliou os efeitos de diferentes quantidades de suplemento sobre o desempenho, características nutricionais e comportamentais de bezerros de corte lactentes, bem como o desempenho de suas mães em pasto tropical. Foram utilizados quarenta e quatro bezerros de corte lactentes machos da raça Nelore com idade média de 120 dias e peso corporal médio de 145±3,7 kg, e suas respectivas mães, com peso corporal médio de 449±6,9 kg. As quantidades de suplemento avaliadas foram as seguintes: 0 = bezerros receberam somente mistura mineral ad libitum; 3, 6 ou 9 = bezerros receberam 3, 6 ou 9 g kg-1 PC de suplemento contendo 25 g de PB kg-1 (matéria natural). O delineamento experimental foi inteiramente casualizado. Foi observado efeito linear positivo (P < 0,01) para o consume de matéria seca e matéria orgânica, e um efeito cúbico (P < 0,07) foi observado para o consume de fibra em detergente neutro (FDN). Houve um efeito quadrático (P < 0,06) para a digestibilidade total da FDN. Observou-se efeito cúbico (P < 0,01) quanto ao desempenho dos bezerros. No entanto, a suplementação não afetou (P ≥ 0,21) a produção de leite e o desempenho de suas mães. A suplementação diminuiu o tempo de pastejo (P < 0,01), mas não influenciou (P ≥ 0,59) o tempo de amamentação dos bezerros. Recomenda-se o fornecimento de suplemento contendo 25 g PB kg-1 na quantidade de 6 g kg-1 PC para bezerros de corte lactentes manejados em pastagem tropical. A suplementação de bezerros de corte lactentes aumenta o consumo de matéria seca, diminui o tempo de pastejo e o consumo de forragem. Contudo, não influencia o tempo de amamentação e o desempenho produtivo de suas mães.(AU)

Performance, endocrine, metabolic, and reproductive responses of Nellore heifers submitted to different supplementation levels pre- and post-weaning.

The present study was conducted to evaluate the effects of high and low supplementation levels pre- and post-weaning on performance, endocrine, metabolic, and reproductive responses of Nellore heifers. Fifty Nellore heifers with 132 ± 9.9 kg average body weight (BW) and 138 ± 19 days of age were supplemented from 4 to 14 months. The heifers were distributed into five supplementation plans: HH-6 g/kg of BW of supplement pre- and post-weaning, HL-6 g/kg of BW of supplement pre-weaning and 3 g/kg post-weaning, LH-3 g/kg of BW pre-weaning and 6 g/kg of BW post-weaning, LL-3 g/kg of BW pre- and post-weaning, and CC-control, no supplementation. Interactions were not significant (P > 0.10). The level of supplement fed pre-weaning did not affect any of the performance variables evaluated at the end of the experiment (P > 0.10). There was a significant effect of supplementation and level of supplementation fed post-weaning on average daily gain (ADG) and final BW (P < 0.05). Overall ADG was also affected only by supplementation and level of supplement fed post-weaning (P < 0.05) with animals receiving 6 g/kg of BW post-weaning gaining more weight. Follicular diameter was greater in animals that received 6 g/kg of BW post-weaning (P < 0.05). In summary, performance, endocrine, metabolic, and reproductive variables evaluated in the current study were improved by the level of supplement fed post-weaning. Heifers receiving supplementation of 6 g/kg of BW post-weaning had greater responses, independent of the level received during the pre-weaning phase.

Evaluation of supplementation plans for suckling beef calves managed on tropical pasture / Avaliação de planos de suplementação para bezerros de corte lactentes manejados em pasto tropical

This study assessed the effects of different amounts of supplement on the productive performance, nutrional caracteristics and behaviour of suckling beef calves, as well as on the productive performance of their dams on tropical pastures. Forty-four male Nellore beef calves with an average age of 120 days and an initial average body weight (BW) of 145±3.7 kg and their respective dams, with an average BW of 449±6.9 kg, were used. The amounts of supplement evaluated were as follows: 0 = calves received only mineral mixture ad libitum; 3, 6, and 9 = calves received 3, 6, or 9 g kg-1 BW of supplement, respectively, containing 250 g CP kg-1 (as-fed). The experimental design was completely randomized. A positive linear effect (P < 0.01) was observed in the intakes of dry matter and organic matter, and a cubic effect (P < 0.07) was observed for the intake of neutral detergent fiber corrected for ash and protein. There was quadratic effect (P < 0.06) for total digestibility of neutral detergent fiber. A cubic effect (P < 0.01) was observed for the calves’ performance. However, the calves’ supplementation did not affect the milk yield and performance (P ≥ 0.21) of their dams. The supplementation decreased grazing time (P < 0.01) but did not influence suckling time (P ≥ 0.59). It is recommended supplying of supplement containing 250 g CP kg-1 (as-fed) in amount 6 g kg-1 BW to suckling beef calves managed in tropical pasture. Supplementation of suckling beef calves increases the intake of dry matter, decreases grazing time and forage intake. However, it does not affect the suckling time and productive performance of their dams.

Este estudo avaliou os efeitos de diferentes quantidades de suplemento sobre o desempenho, características nutricionais e comportamentais de bezerros de corte lactentes, bem como o desempenho de suas mães em pasto tropical. Foram utilizados quarenta e quatro bezerros de corte lactentes machos da raça Nelore com idade média de 120 dias e peso corporal médio de 145±3,7 kg, e suas respectivas mães, com peso corporal médio de 449±6,9 kg. As quantidades de suplemento avaliadas foram as seguintes: 0 = bezerros receberam somente mistura mineral ad libitum; 3, 6 ou 9 = bezerros receberam 3, 6 ou 9 g kg-1 PC de suplemento contendo 25 g de PB kg-1 (matéria natural). O delineamento experimental foi inteiramente casualizado. Foi observado efeito linear positivo (P < 0,01) para o consume de matéria seca e matéria orgânica, e um efeito cúbico (P < 0,07) foi observado para o consume de fibra em detergente neutro (FDN). Houve um efeito quadrático (P < 0,06) para a digestibilidade total da FDN. Observou-se efeito cúbico (P < 0,01) quanto ao desempenho dos bezerros. No entanto, a suplementação não afetou (P ≥ 0,21) a produção de leite e o desempenho de suas mães. A suplementação diminuiu o tempo de pastejo (P < 0,01), mas não influenciou (P ≥ 0,59) o tempo de amamentação dos bezerros. Recomenda-se o fornecimento de suplemento contendo 25 g PB kg-1 na quantidade de 6 g kg-1 PC para bezerros de corte lactentes manejados em pastagem tropical. A suplementação de bezerros de corte lactentes aumenta o consumo de matéria seca, diminui o tempo de pastejo e o consumo de forragem. Contudo, não influencia o tempo de amamentação e o desempenho produtivo de suas mães.

Supplementation of grazing suckling beef calves receiving different energy sources / Suplementação de bezerros de corte lactentes em pastejo com diferentes fontes energéticas

The aim of this study was to evaluate the effect of different energy sources - corn, sorghum, and wheat bran - on performance, intake, digestibility, and nitrogen utilization efficiency of beef calves subjected to creep feeding. Thirty-four calves (12 males and 22 females) with initial age and weight of four months and 108±3.9 kg, respectively, were used in a randomized-block experimental design with four treatments and two blocks (males and females). Treatments were control (MM), a mineral mixture ad libitum; corn (C); corn + sorghum (C+S); and corn + sorghum + wheat bran (C+S+WB). Supplements contained approximately 20% crude protein (CP), and were fed in the amount of 0.5% of body weight. Supplemented animals had higher performance (P 0.05) when compared with those on treatment MM. Supplementation increased (P 0.05) the intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber corrected for ash and protein (NDFap), non-fibrous carbohydrates (NFC), digestible neutral detergent fiber (dNDF), and digestible organic matter (dOM). The digestibility of NFC was higher (P 0.05) in the supplemented treatments. The C+S and C+S+WB treatments provided increased digestibility (P 0.05) of OM, CP, and NDFap. The synthesis of nitrogen compounds was higher (P 0.05) in animals on treatment C as compared with those on the other supple...(AU)

O objetivo deste trabalho foi avaliar o efeito de diferentes fontes energéticas, milho, sorgo e farelo de trigo, sobre o desempenho, o consumo, a digestibilidade aparente total dos constituintes da dieta e a eficiência de utilização dos compostos nitrogenados em bezerros de corte submetidos ao creep feeding. Foram utilizados 34 bezerros lactentes (12 machos e 22 fêmeas) com idade e peso médio inicial de quatro meses e 108±3,9 kg, respectivamente. O experimento foi conduzido em blocos casualizados com quatro tratamentos e dois blocos (machos e fêmeas). Os tratamentos foram: controle (MM), fornecimento de mistura mineral ad libitum aos animais; milho (M); milho + sorgo (M+S) e milho + sorgo + farelo de trigo (M+S+FT). Os suplementos continham aproximadamente 20% de proteína bruta (PB) e foram fornecidos na quantidade de 5 g kg-1do peso corporal. Os animais suplementados apresentaram maior (P 0,05) ganho de peso quando comparados com os animais do tratamento MM. A suplementação aumentou (P 0,05) os consumos de matéria seca (MS), matéria orgânica (MO), PB, fibra em detergente neutro corrigida para cinzas e proteína (FDNcp), carboidrato não fibroso (CNF), fibra em detergente neutro digerida (FDNd) e matéria orgânica digerida (MOD). A digestibilidade aparente total do CNF foi maior (P 0,05) nos animais suplementados. Os tratamentos M+S e M+S+FT apresentaram maior...(AU)

Supplementation of grazing suckling beef calves receiving different energy sources / Suplementação de bezerros de corte lactentes em pastejo com diferentes fontes energéticas

The aim of this study was to evaluate the effect of different energy sources - corn, sorghum, and wheat bran - on performance, intake, digestibility, and nitrogen utilization efficiency of beef calves subjected to creep feeding. Thirty-four calves (12 males and 22 females) with initial age and weight of four months and 108±3.9 kg, respectively, were used in a randomized-block experimental design with four treatments and two blocks (males and females). Treatments were control (MM), a mineral mixture ad libitum; corn (C); corn + sorghum (C+S); and corn + sorghum + wheat bran (C+S+WB). Supplements contained approximately 20% crude protein (CP), and were fed in the amount of 0.5% of body weight. Supplemented animals had higher performance (P 0.05) when compared with those on treatment MM. Supplementation increased (P 0.05) the intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber corrected for ash and protein (NDFap), non-fibrous carbohydrates (NFC), digestible neutral detergent fiber (dNDF), and digestible organic matter (dOM). The digestibility of NFC was higher (P 0.05) in the supplemented treatments. The C+S and C+S+WB treatments provided increased digestibility (P 0.05) of OM, CP, and NDFap. The synthesis of nitrogen compounds was higher (P 0.05) in animals on treatment C as compared with those on the other supple...

O objetivo deste trabalho foi avaliar o efeito de diferentes fontes energéticas, milho, sorgo e farelo de trigo, sobre o desempenho, o consumo, a digestibilidade aparente total dos constituintes da dieta e a eficiência de utilização dos compostos nitrogenados em bezerros de corte submetidos ao creep feeding. Foram utilizados 34 bezerros lactentes (12 machos e 22 fêmeas) com idade e peso médio inicial de quatro meses e 108±3,9 kg, respectivamente. O experimento foi conduzido em blocos casualizados com quatro tratamentos e dois blocos (machos e fêmeas). Os tratamentos foram: controle (MM), fornecimento de mistura mineral ad libitum aos animais; milho (M); milho + sorgo (M+S) e milho + sorgo + farelo de trigo (M+S+FT). Os suplementos continham aproximadamente 20% de proteína bruta (PB) e foram fornecidos na quantidade de 5 g kg-1do peso corporal. Os animais suplementados apresentaram maior (P 0,05) ganho de peso quando comparados com os animais do tratamento MM. A suplementação aumentou (P 0,05) os consumos de matéria seca (MS), matéria orgânica (MO), PB, fibra em detergente neutro corrigida para cinzas e proteína (FDNcp), carboidrato não fibroso (CNF), fibra em detergente neutro digerida (FDNd) e matéria orgânica digerida (MOD). A digestibilidade aparente total do CNF foi maior (P 0,05) nos animais suplementados. Os tratamentos M+S e M+S+FT apresentaram maior...

Quantities of supplements for grazing beef heifers in the dry-rainy transition season / Quantidades de suplementos para novilhas de corte sob pastejo durante o período de transição seca - águas

The objective of this study was to evaluate the effect of supplying different quantities of multiple supplements on the nutritional characteristics and productive performance of heifers during the postweaning phase on Urochloa decumbens pastures during the dry-rainy transition season. Twentyfour heifers (average initial age and weight of 11 mo and 243±6 kg, respectively) were used. The experimental design was completely randomized, with four treatments and six replicates. A supplement containing 25% CP was used, and treatments consisted of the following four levels of supplements: 0, 0.5, 1.0 and 1.5 kg. The animals in the different treatments received a mineral mixture ad libitum. A positive linear effect (P<0.10) was observed on ADG and final body weight with the quantities of supplements. An increasing linear effect (P<0.10) was found on the intakes of DM, OM, CP, EE, NFC and TDN with the elevation in the amount of the supplement provided, which was not observed for NDFap intake. A cubic effect was observed (P<0.10) on the apparent digestibility of OM, CP, NDFap, NFC and concentration of TDN among the quantities of multiple supplements. Supplement levels increased (P<0.10) the digestibility coefficient of EE. An increasing linear response was detected (P<0.10) in urine urea nitrogen excretion, serum urea nitrogen (SUN) and flow of microbial nitrogen (MICN) compounds with the quantities of supplement. No difference was observed (P<0.10) in theefficiency of microbial synthesis between the supplementation levels. The quantities of supplement had a decreasing linear effect (P<0.10) on the relative MICN. In conclusion, supplying higher amounts of multiple supplements during the dry-rainy transition season improves the productive performance and nutritional characteristics of beef heifers reared on pasture.(AU)

O objetivo do trabalho foi avaliar o efeito do fornecimento de diferentes quantidades de suplementos múltiplos sobre as características nutricionais e desempenho produtivo de novilhas durante a fase de recria em pastagens com Urochloa decumbens no período de transição seca-águas. Foram utilizadas 24 novilhas com idade e peso médio inicial de 11 meses e 243±3 kg, respectivamente. O delineamento foi inteiramente casualizado com quatro tratamentos e seis repetições. Utilizou-se um suplemento com 25% de PB. Os tratamentos consistiam em quatro quantidades de suplementos: 0; 0,5; 1,0 e 1,5 kg respectivamente. Os animais dos diferentes tratamentos receberam mistura mineral ad libitum. Observou-se efeito linear positivo (P<0,10) no GMD e peso corporal final (PCF) com as quantidades de suplementos. Foi verificado efeito linear crescente (P<0,10) no consumo de MS, MO, PB, EE, CNF e NDT com o fornecimento de maiores quantidades de suplemento; efeito não apresentado no consumo de FDNcp. Evidenciou-se efeito cúbico (P<0,10) sobre a digestibilidade aparente da MO, PB, FDNcp, CNF e concentração de NDT entre as quantidades de suplementos múltiplos. As quantidades de suplementos aumentaram (P<0,10) o coeficiente de digestibilidade do EE. Verificou-se comportamento linear crescente (P<0,10) sobre a excreção urinária de nitrogênio uréico (NUU), nitrogênio uréico no soro (NUS) e fluxo de compostos nitrogenados microbianos (NMIC) com as quantidades de suplementos. Não foi observada diferença (P<0,10) das quantidades de suplementação sobre a eficiência de síntese microbiana. As quantidades de suplementos afetaram de forma linear decrescente (P<0,10) o NMICR.Conclui-se que o fornecimento de maiores quantidades de suplementos múltiplos durante a época de transição seca-águas melhora o desempenho produtivo e características nutricionais de novilhas de corte criadas em pastagens.(AU)

Substitution of soybean meal for cottonseed meal in multiple supplements for grazing beef heifers in the dry season / Substituição do farelo de soja pelo farelo de algodão em suplementos para novilhas de corte sob pastejo durante o período da seca

The objective of this study was to evaluate the effect of substituting soybean meal for cottonseed meal in multiple supplements on the nutritional characteristics and performance of beef heifers in their postweaning phase on Brachiaria decumbens pastures during the dry season. Twenty-four Nellore beef heifers (average initial age and weight of 8 mo and 210±6 kg, respectively) were used. The design was completely randomized, with four treatments and six replicates. Supplements contained approximately 30% crude protein (CP) and a progressive substitution of soybean meal for cottonseed meal (0, 50 and 100%). The control animals received only a mineral mixture ad libitum, and those on the other treatments received supplementation at 1.0 kg/animal/day. No differences were found in ADG between supplemented and control animals (P>0.10). Supplementation increased crude protein (CP) intake only (P<0.10). The level of substitution of soybean meal for cottonseed meal did not affect (P>0.10) the intake of supplemented animals. Supplementation elevated the apparent digestibility coefficients (P<0.10) of OM, CP, NFC and TDN, but not EE or NDFap (P>0.10). A positive linear effect (P<0.10) of the level of substitution of soybean meal for cottonseed cake was observed on the digestibility of OM, NFC and TDN. Supplementation and the level of substitution had an effect (P<0.100.10) on the serum urea nitrogen and urine urea nitrogen contents. Supplementation or substitution level had no effect on theflow of microbial nitrogen to the intestine (MICN) or efficiency of microbial protein synthesis (EMPS) (P>0.10). Substitution caused a decreasing linear effect (P<0.10) on microbial nitrogen/nitrogen intake ratio (MICNR). In conclusion, substitution of soybean meal for cottonseed meal in multiple supplementsduring the dry season does not impair the productive performance of beef heifers.(AU)

Objetivou-se avaliar o efeito da substituição do farelo de soja pelo farelo de algodão em suplementos múltiplos sobre as características nutricionais e desempenho produtivo de novilhas de corte em fase de recria em pastagens de Brachiaria decumbens no período da seca. Foram utilizadas 24 novilhas de corte nelore com idade e peso médio inicial de 8 meses e 210±6 kg, respectivamente. O delineamento foi inteiramente casualizado com quatro tratamentos e seis repetições. Os suplementos continham aproximadamente 30% de proteína bruta (PB) e substituição progressiva do farelo de soja pelo farelo de algodão em 0, 50 e 100%. Aos animais do tratamento controle foi fornecida apenas mistura mineral ad libitum e aos demais tratamentos foram fornecidos 1,0 kg/animal/dia de suplemento. Não houve diferença de GMD entre os animais suplementados e os animais controle (P>0,10). A suplementação aumentou apenas o consumo de proteína bruta (PB) (P<0,10). O nível de substituição de farelo de soja pelo farelo de algodão não afetou (P>0,10) o consumo nos animais suplementados. A suplementação ampliou os coeficientes de digestibilidade aparente (P<0,10) da MO, PB, CFN e NDT com exceção do EE e da FDNcp (P>0,10). Observou-se efeito linear positivo (P<0,10) do nível de substituição de farelo de soja pelo farelo de algodão sobre a digestibilidade da MO, CNF e NDT. Houve efeito da suplementação e do nível de substituição (P<0,10) sobre o teor de nitrogênio ureico no soro e nitrogênioureico na urina. Não houve efeito da suplementação e do nível de substituição sobre o fluxo de nitrogênio microbiano ao intestino (NMIC) e eficiência de síntese de proteína microbiana (EFM) (P>0,10). Foi verificado efeito linear decrescente (P<0,10) da substituição sobre a relação nitrogênio microbiano/nitrogênio ingerido (NMICR). Conclui-se que a substituição do farelo de soja pelo farelo de algodão em suplementos múltiplos durante a época seca não prejudica o desempenho produtivo de novilhas de corte.(AU)

Substitution of soybean meal for cottonseed meal in multiple supplements for grazing beef heifers in the dry season / Substituição do farelo de soja pelo farelo de algodão em suplementos para novilhas de corte sob pastejo durante o período da seca

The objective of this study was to evaluate the effect of substituting soybean meal for cottonseed meal in multiple supplements on the nutritional characteristics and performance of beef heifers in their postweaning phase on Brachiaria decumbens pastures during the dry season. Twenty-four Nellore beef heifers (average initial age and weight of 8 mo and 210±6 kg, respectively) were used. The design was completely randomized, with four treatments and six replicates. Supplements contained approximately 30% crude protein (CP) and a progressive substitution of soybean meal for cottonseed meal (0, 50 and 100%). The control animals received only a mineral mixture ad libitum, and those on the other treatments received supplementation at 1.0 kg/animal/day. No differences were found in ADG between supplemented and control animals (P>0.10). Supplementation increased crude protein (CP) intake only (P0.10) the intake of supplemented animals. Supplementation elevated the apparent digestibility coefficients (P0.10). A positive linear effect (P0.10). Substitution caused a decreasing linear effect (P<0.10) on microbial nitrogen/nitrogen intake ratio (MICNR). In conclusion, substitution of soybean meal for cottonseed meal in multiple supplementsduring the dry season does not impair the productive performance of beef heifers.

Objetivou-se avaliar o efeito da substituição do farelo de soja pelo farelo de algodão em suplementos múltiplos sobre as características nutricionais e desempenho produtivo de novilhas de corte em fase de recria em pastagens de Brachiaria decumbens no período da seca. Foram utilizadas 24 novilhas de corte nelore com idade e peso médio inicial de 8 meses e 210±6 kg, respectivamente. O delineamento foi inteiramente casualizado com quatro tratamentos e seis repetições. Os suplementos continham aproximadamente 30% de proteína bruta (PB) e substituição progressiva do farelo de soja pelo farelo de algodão em 0, 50 e 100%. Aos animais do tratamento controle foi fornecida apenas mistura mineral ad libitum e aos demais tratamentos foram fornecidos 1,0 kg/animal/dia de suplemento. Não houve diferença de GMD entre os animais suplementados e os animais controle (P>0,10). A suplementação aumentou apenas o consumo de proteína bruta (PB) (P0,10) o consumo nos animais suplementados. A suplementação ampliou os coeficientes de digestibilidade aparente (P0,10). Observou-se efeito linear positivo (P0,10). Foi verificado efeito linear decrescente (P<0,10) da substituição sobre a relação nitrogênio microbiano/nitrogênio ingerido (NMICR). Conclui-se que a substituição do farelo de soja pelo farelo de algodão em suplementos múltiplos durante a época seca não prejudica o desempenho produtivo de novilhas de corte.

Quantities of supplements for grazing beef heifers in the dry-rainy transition season / Quantidades de suplementos para novilhas de corte sob pastejo durante o período de transição seca - águas

The objective of this study was to evaluate the effect of supplying different quantities of multiple supplements on the nutritional characteristics and productive performance of heifers during the postweaning phase on Urochloa decumbens pastures during the dry-rainy transition season. Twentyfour heifers (average initial age and weight of 11 mo and 243±6 kg, respectively) were used. The experimental design was completely randomized, with four treatments and six replicates. A supplement containing 25% CP was used, and treatments consisted of the following four levels of supplements: 0, 0.5, 1.0 and 1.5 kg. The animals in the different treatments received a mineral mixture ad libitum. A positive linear effect (P<0.10) was observed on ADG and final body weight with the quantities of supplements. An increasing linear effect (P<0.10) was found on the intakes of DM, OM, CP, EE, NFC and TDN with the elevation in the amount of the supplement provided, which was not observed for NDFap intake. A cubic effect was observed (P<0.10) on the apparent digestibility of OM, CP, NDFap, NFC and concentration of TDN among the quantities of multiple supplements. Supplement levels increased (P<0.10) the digestibility coefficient of EE. An increasing linear response was detected (P<0.10) in urine urea nitrogen excretion, serum urea nitrogen (SUN) and flow of microbial nitrogen (MICN) compounds with the quantities of supplement. No difference was observed (P<0.10) in theefficiency of microbial synthesis between the supplementation levels. The quantities of supplement had a decreasing linear effect (P<0.10) on the relative MICN. In conclusion, supplying higher amounts of multiple supplements during the dry-rainy transition season improves the productive performance and nutritional characteristics of beef heifers reared on pasture.

O objetivo do trabalho foi avaliar o efeito do fornecimento de diferentes quantidades de suplementos múltiplos sobre as características nutricionais e desempenho produtivo de novilhas durante a fase de recria em pastagens com Urochloa decumbens no período de transição seca-águas. Foram utilizadas 24 novilhas com idade e peso médio inicial de 11 meses e 243±3 kg, respectivamente. O delineamento foi inteiramente casualizado com quatro tratamentos e seis repetições. Utilizou-se um suplemento com 25% de PB. Os tratamentos consistiam em quatro quantidades de suplementos: 0; 0,5; 1,0 e 1,5 kg respectivamente. Os animais dos diferentes tratamentos receberam mistura mineral ad libitum. Observou-se efeito linear positivo (P<0,10) no GMD e peso corporal final (PCF) com as quantidades de suplementos. Foi verificado efeito linear crescente (P<0,10) no consumo de MS, MO, PB, EE, CNF e NDT com o fornecimento de maiores quantidades de suplemento; efeito não apresentado no consumo de FDNcp. Evidenciou-se efeito cúbico (P<0,10) sobre a digestibilidade aparente da MO, PB, FDNcp, CNF e concentração de NDT entre as quantidades de suplementos múltiplos. As quantidades de suplementos aumentaram (P<0,10) o coeficiente de digestibilidade do EE. Verificou-se comportamento linear crescente (P<0,10) sobre a excreção urinária de nitrogênio uréico (NUU), nitrogênio uréico no soro (NUS) e fluxo de compostos nitrogenados microbianos (NMIC) com as quantidades de suplementos. Não foi observada diferença (P<0,10) das quantidades de suplementação sobre a eficiência de síntese microbiana. As quantidades de suplementos afetaram de forma linear decrescente (P<0,10) o NMICR.Conclui-se que o fornecimento de maiores quantidades de suplementos múltiplos durante a época de transição seca-águas melhora o desempenho produtivo e características nutricionais de novilhas de corte criadas em pastagens.

Suplementação em sistema de creep-feeding de bezerros de corte lactentes e avaliação nutricional de matrizes de corte / Supplementation of suckling beef calves on a creep-feeding system and nutritional evaluation of lactating beef dams

This study was conducted to evaluate the productive and nutritional performance of suckling calves fed only a mineral mix (MM) or different levels of multiple supplement and the milk yield and nutritional parameters of beef cows on Uruchloa decumbens pastures. Thirty-two suckling calves, with an average age of 3 months and average initial weight of 109.3 ± 0.84 kg, and their respective mothers, with an average initial weight of 447.2 ± 47.1 kg, were used. The experimental design was completely randomized. The supplement contained approximately 25% crude protein (CP), and treatments consisted of the supply of different of multiple supplement levels for the calves. The levels of supply of the supplements were 0.2, 0.4, and 0.6% of the body weight for treatments N0.2, N0.4, and N0.6, respectively. The animals from the control treatment (MM) received only an MM ad libitum. The average daily gain (ADG) of the calves was 731.2, 810.6, 822.7, and 895.2 grams for treatments MM, N0.2, N0.4, and N0.6, respectively. Supplemented calves showed greater weight gain. The multiple supplement levels offered to the calves had a positive linear effect (P 0.10) on their ADG. The intakes in kg/ day of dry matter (DM), organic matter (OM), CP, non-fibrous carbohydrates (NFC), digestible DM, digestible neutral detergent fiber (NDF), and total digestible nutrients (TDN) were higher (P<0.10) for animals that received multiple supplements compared with those fed only an MM. The levels of supply of multiple supplements had an increasing linear effect on ether extract (EE) intake, and a quadratic effect was found on DM intake, forage DM, OM, forage OM, CP, NFC, digestible DM, and TDN. The total apparent digestibility coefficients of DM, OM, NDF, NFC, and TDN were higher (P<0.10) for the animals that received multiple supplements.[...](AU)

Este trabalho foi realizado para avaliar o desempenho produtivo e nutricional de bezerros lactentes recebendo apenas mistura mineral ou diferentes níveis de suplementos múltiplos e a produção de leite e os parâmetros nutricionais de vacas de corte em pastagens de Uruchloa decumbens. Utilizaram-se 32 bezerros de corte, lactentes, com idade média de 3 meses e peso médio inicial de 109,3 + 0,84 kg, e suas respectivas mães com peso inicial médio de 447,2 + 47,1 kg. O delineamento experimental foi o inteiramente casualizado. O suplemento continha aproximadamente 25% de proteína bruta (PB) e os tratamentos consistiram-se do fornecimento de diferentes níveis de suplementos múltiplos para os bezerros. Os níveis de fornecimento de suplementos foram 0,2; 0,4 e 0,6% do peso corporal para os tratamentos N0,2, N0,4, e N0,6, respectivamente. Os animais do tratamento controle (MM) receberam exclusivamente mistura mineral ad libitum. O ganho médio diário (g) dos bezerros foi 731,2; 810,6; 822,7e 895,2, respectivamente, para os tratamentos MM, N0,2, N0,4, e N0,6. Os bezerros suplementadas apresentaram maior ganho em peso. Houve efeito linear positivo do nível de suplemento múltiplo fornecido aos bezerros (P 0,10) sobre o ganho médio diário. Os consumos em kg/dia de matéria seca (MS), matéria orgânica (MO), PB, carboidratos não fibrosos (CNF), MS digerida, fibra em detergente neutro digerida e nutrientes digestíveis totais foram superiores (P<0,10) para os animais que receberam suplementos múltiplos em relação aos animais que receberam apenas mistura mineral. Entre os níveis de fornecimento de suplementos múltiplos observou-se efeito linear crescente sobre o consumo de extrato etéreo e efeito quadrático sobre o consumo de MS, matéria seca de forragem, MO, matéria orgânica de forragem, PB, CNF, matéria seca digerida e NDT. Os coeficientes de digestibilidade aparente total da MS, MO, FDN, CNF e NDT foram superiores (P<0,10) para os animais que receberam suplementos múltiplos.[...](AU)

Níveis de proteína bruta em suplementos multiplos para novilhas Nelore em pastejo na época seca / Levels of crude protein in multiple supplements for Nelore heifers on pasture in the dry season

Avaliou-se o efeito de níveis de proteína bruta em suplementos sobre o desempenho, consumo, digestibilidade e eficiência microbiana. Foram utilizadas 40 novilhas Nelore, com idade inicial média de oito meses e peso inicial médio de 230 + 3,39 kg. Os suplementos avaliados foram: mistura mineral fornecida ad libitum (MM), suplementos contendo 10%, 20%, 30% e 40% de proteína bruta (PB), constituindo os tratamentos PB10, PB20, PB30, PB40, respectivamente. Observou-se maior peso corporal final (PCF) e ganho médio diário de peso (GMD) nos animais suplementados em relação aos não suplementados (P 0,10). Os consumos de todos os nutrientes foram maiores (P 0,10) nos animais suplementados em relação aos não suplementados. O consumo de proteína bruta apresentou efeito linear crescente, com o aumento dos níveis de PB nos suplementos. Observou-se efeito quadrático na digestibilidade da PB com o aumento dos níveis de PB nos suplementos. A produção de nitrogênio microbiano (Nmic), nitrogênio ureico no soro (NUS) e a relação nitrogênio ureico na urina/nitrogênio da creatinina (NUU/Ncre) foram maiores (P 0,10) em animais suplementados. Observou-se efeito quadrático sobre a produção de Nmic, eficiência microbiana (Emic), NUS e NUU/Ncre com o aumento dos níveis de PB nos suplementos múltiplos. A suplementação múltipla proporciona maiores ganhos de peso e peso corporal final no período pós desmama de novilhas Nelore.(AU)

It was evaluated the effect of levels of crude protein supplement on performance, intake, digestibility and microbial efficiency. Forty Nelore heifers, with an initial average age of eight months and an initial average weight of 230 + 3,39 kg, were used. The evaluated supplements were: mineral mix provided ad libitum (MM), supplements containing 10%, 20%, 30% and 40% crude protein (CP), representing the treatments PB10, PB20, PB30, PB40, respectively. It was observed a higher final body weight and weight gain for supplemented animals compared to non-supplemented (P 0.10). The intake of all nutrients were higher (P 0.10) for supplemented animals compared to non-supplemented. The crude protein intake had increased linearly with increasing levels of CP in supplements. The digestibility of DM, OM, CP and TDN were higher (P 0.10) in supplemented animals compared to non-supplemented. There was a quadratic effect on CP digestibility with increased levels of CP in supplements. The production of microbial nitrogen (N mic), serum urea nitrogen (NUS) and reason urea nitrogen in the urine/creatinine nitrogen (NUU/Ncre) were higher (P 0.10) for supplemented animals. Quadratic effect was observed on production of Nmic, microbial efficiency (Emic), NUS and NUU/Ncre with increased levels of CP in multiple supplements. The multiple supplementation provides higher weight gain and final body weight in the period after weaning from Nellore females.(AU)

Níveis de proteína bruta em suplementos multiplos para novilhas Nelore em pastejo na época seca / Levels of crude protein in multiple supplements for Nelore heifers on pasture in the dry season

Avaliou-se o efeito de níveis de proteína bruta em suplementos sobre o desempenho, consumo, digestibilidade e eficiência microbiana. Foram utilizadas 40 novilhas Nelore, com idade inicial média de oito meses e peso inicial médio de 230 + 3,39 kg. Os suplementos avaliados foram: mistura mineral fornecida ad libitum (MM), suplementos contendo 10%, 20%, 30% e 40% de proteína bruta (PB), constituindo os tratamentos PB10, PB20, PB30, PB40, respectivamente. Observou-se maior peso corporal final (PCF) e ganho médio diário de peso (GMD) nos animais suplementados em relação aos não suplementados (P 0,10). Os consumos de todos os nutrientes foram maiores (P 0,10) nos animais suplementados em relação aos não suplementados. O consumo de proteína bruta apresentou efeito linear crescente, com o aumento dos níveis de PB nos suplementos. Observou-se efeito quadrático na digestibilidade da PB com o aumento dos níveis de PB nos suplementos. A produção de nitrogênio microbiano (Nmic), nitrogênio ureico no soro (NUS) e a relação nitrogênio ureico na urina/nitrogênio da creatinina (NUU/Ncre) foram maiores (P 0,10) em animais suplementados. Observou-se efeito quadrático sobre a produção de Nmic, eficiência microbiana (Emic), NUS e NUU/Ncre com o aumento dos níveis de PB nos suplementos múltiplos. A suplementação múltipla proporciona maiores ganhos de peso e peso corporal final no período pós desmama de novilhas Nelore.

It was evaluated the effect of levels of crude protein supplement on performance, intake, digestibility and microbial efficiency. Forty Nelore heifers, with an initial average age of eight months and an initial average weight of 230 + 3,39 kg, were used. The evaluated supplements were: mineral mix provided ad libitum (MM), supplements containing 10%, 20%, 30% and 40% crude protein (CP), representing the treatments PB10, PB20, PB30, PB40, respectively. It was observed a higher final body weight and weight gain for supplemented animals compared to non-supplemented (P 0.10). The intake of all nutrients were higher (P 0.10) for supplemented animals compared to non-supplemented. The crude protein intake had increased linearly with increasing levels of CP in supplements. The digestibility of DM, OM, CP and TDN were higher (P 0.10) in supplemented animals compared to non-supplemented. There was a quadratic effect on CP digestibility with increased levels of CP in supplements. The production of microbial nitrogen (N mic), serum urea nitrogen (NUS) and reason urea nitrogen in the urine/creatinine nitrogen (NUU/Ncre) were higher (P 0.10) for supplemented animals. Quadratic effect was observed on production of Nmic, microbial efficiency (Emic), NUS and NUU/Ncre with increased levels of CP in multiple supplements. The multiple supplementation provides higher weight gain and final body weight in the period after weaning from Nellore females.

Suplementação em sistema de creep-feeding de bezerros de corte lactentes e avaliação nutricional de matrizes de corte / Supplementation of suckling beef calves on a creep-feeding system and nutritional evaluation of lactating beef dams

This study was conducted to evaluate the productive and nutritional performance of suckling calves fed only a mineral mix (MM) or different levels of multiple supplement and the milk yield and nutritional parameters of beef cows on Uruchloa decumbens pastures. Thirty-two suckling calves, with an average age of 3 months and average initial weight of 109.3 ± 0.84 kg, and their respective mothers, with an average initial weight of 447.2 ± 47.1 kg, were used. The experimental design was completely randomized. The supplement contained approximately 25% crude protein (CP), and treatments consisted of the supply of different of multiple supplement levels for the calves. The levels of supply of the supplements were 0.2, 0.4, and 0.6% of the body weight for treatments N0.2, N0.4, and N0.6, respectively. The animals from the control treatment (MM) received only an MM ad libitum. The average daily gain (ADG) of the calves was 731.2, 810.6, 822.7, and 895.2 grams for treatments MM, N0.2, N0.4, and N0.6, respectively. Supplemented calves showed greater weight gain. The multiple supplement levels offered to the calves had a positive linear effect (P 0.10) on their ADG. The intakes in kg/ day of dry matter (DM), organic matter (OM), CP, non-fibrous carbohydrates (NFC), digestible DM, digestible neutral detergent fiber (NDF), and total digestible nutrients (TDN) were higher (P<0.10) for animals that received multiple supplements compared with those fed only an MM. The levels of supply of multiple supplements had an increasing linear effect on ether extract (EE) intake, and a quadratic effect was found on DM intake, forage DM, OM, forage OM, CP, NFC, digestible DM, and TDN. The total apparent digestibility coefficients of DM, OM, NDF, NFC, and TDN were higher (P<0.10) for the animals that received multiple supplements.[...]

Este trabalho foi realizado para avaliar o desempenho produtivo e nutricional de bezerros lactentes recebendo apenas mistura mineral ou diferentes níveis de suplementos múltiplos e a produção de leite e os parâmetros nutricionais de vacas de corte em pastagens de Uruchloa decumbens. Utilizaram-se 32 bezerros de corte, lactentes, com idade média de 3 meses e peso médio inicial de 109,3 + 0,84 kg, e suas respectivas mães com peso inicial médio de 447,2 + 47,1 kg. O delineamento experimental foi o inteiramente casualizado. O suplemento continha aproximadamente 25% de proteína bruta (PB) e os tratamentos consistiram-se do fornecimento de diferentes níveis de suplementos múltiplos para os bezerros. Os níveis de fornecimento de suplementos foram 0,2; 0,4 e 0,6% do peso corporal para os tratamentos N0,2, N0,4, e N0,6, respectivamente. Os animais do tratamento controle (MM) receberam exclusivamente mistura mineral ad libitum. O ganho médio diário (g) dos bezerros foi 731,2; 810,6; 822,7e 895,2, respectivamente, para os tratamentos MM, N0,2, N0,4, e N0,6. Os bezerros suplementadas apresentaram maior ganho em peso. Houve efeito linear positivo do nível de suplemento múltiplo fornecido aos bezerros (P 0,10) sobre o ganho médio diário. Os consumos em kg/dia de matéria seca (MS), matéria orgânica (MO), PB, carboidratos não fibrosos (CNF), MS digerida, fibra em detergente neutro digerida e nutrientes digestíveis totais foram superiores (P<0,10) para os animais que receberam suplementos múltiplos em relação aos animais que receberam apenas mistura mineral. Entre os níveis de fornecimento de suplementos múltiplos observou-se efeito linear crescente sobre o consumo de extrato etéreo e efeito quadrático sobre o consumo de MS, matéria seca de forragem, MO, matéria orgânica de forragem, PB, CNF, matéria seca digerida e NDT. Os coeficientes de digestibilidade aparente total da MS, MO, FDN, CNF e NDT foram superiores (P<0,10) para os animais que receberam suplementos múltiplos.[...]

Parâmetros nutricionais e produtivos de bezerras suplementadas a pasto com diferentes fontes de alimentos protéicos / Nutritional parameters and production of calves on pasture supplemented with different sources of protein foods

Objetivou-se avaliar os efeitos de suplementos múltiplos com diferentes fontes protéicas sobre o desempenho produtivo, consumo, digestibilidade dos componentes da dieta e eficiência de síntese de proteína bruta microbiana de bezerras de corte lactentes sob pastejo. O trabalho foi realizado durante o período de transição de águas-secas (Fevereiro á Julho de 2012), utilizando-se quatro piquetes com média de 4,5 há; para tal, foram utilizadas vinte quatro bezerras com idade e peso médio inicial de 3 meses e 113 kg, respectivamente. Os tratamentos foram: mistura mineral (MM) ad libitum, farelo de soja (PBFS), farelo de algodão 38% de Proteína bruta (PBFA) e combinação de farelo de soja com farelo de algodão 38% de Proteína bruta (PBFS+FA). Não se verificou efeito (P>0,10) das diferentes fontes protéicas sobre o ganho médio diário (GMD) entre os animais que receberam suplementos múltiplos, assim como não foi verificado diferença no GMD entre os suplementados com suplemento múltiplo e suplementados apenas com mistura mineral. Sendo assim, o farelo de algodão pode substituir o farelo de soja ou ser utilizado em associação ao farelo de soja em suplementos múltiplos para bezerras de corte lactentes.(AU)

The aim of this study was to evaluate the effects of multiple supplements with different protein sources on the performance, intake, nutrient digestibility, and microbial protein production efficiency of lactating beef heifers under grazing. The experiment was carried out during the period of transition from water-dry (February to July, 2012) using four paddocks with average of 4.5 ha. Twenty four lactating beef heifers with initial body weight of 113 kg and 3 month old, were used. The treatments were: mineral mixed (MM) ad libitum, soybean meal (SM), cottonseed meal 38% crude protein (CM), and combination of SM and CM (SMCM). There was not observed effect (P>0.10) of different protein sources on average daily gain (ADG) between the animals that received multiple supplement as well as difference was notverified for ADG between the multiple supplements and MM. Therefore, cottonseed meal can replace soybean meal or can be used in association to the soybean meal on multiple supplements for lactating beef heifers.(AU)

Parâmetros nutricionais e produtivos de bezerras suplementadas a pasto com diferentes fontes de alimentos protéicos / Nutritional parameters and production of calves on pasture supplemented with different sources of protein foods

Objetivou-se avaliar os efeitos de suplementos múltiplos com diferentes fontes protéicas sobre o desempenho produtivo, consumo, digestibilidade dos componentes da dieta e eficiência de síntese de proteína bruta microbiana de bezerras de corte lactentes sob pastejo. O trabalho foi realizado durante o período de transição de águas-secas (Fevereiro á Julho de 2012), utilizando-se quatro piquetes com média de 4,5 há; para tal, foram utilizadas vinte quatro bezerras com idade e peso médio inicial de 3 meses e 113 kg, respectivamente. Os tratamentos foram: mistura mineral (MM) ad libitum, farelo de soja (PBFS), farelo de algodão 38% de Proteína bruta (PBFA) e combinação de farelo de soja com farelo de algodão 38% de Proteína bruta (PBFS+FA). Não se verificou efeito (P>0,10) das diferentes fontes protéicas sobre o ganho médio diário (GMD) entre os animais que receberam suplementos múltiplos, assim como não foi verificado diferença no GMD entre os suplementados com suplemento múltiplo e suplementados apenas com mistura mineral. Sendo assim, o farelo de algodão pode substituir o farelo de soja ou ser utilizado em associação ao farelo de soja em suplementos múltiplos para bezerras de corte lactentes.

The aim of this study was to evaluate the effects of multiple supplements with different protein sources on the performance, intake, nutrient digestibility, and microbial protein production efficiency of lactating beef heifers under grazing. The experiment was carried out during the period of transition from water-dry (February to July, 2012) using four paddocks with average of 4.5 ha. Twenty four lactating beef heifers with initial body weight of 113 kg and 3 month old, were used. The treatments were: mineral mixed (MM) ad libitum, soybean meal (SM), cottonseed meal 38% crude protein (CM), and combination of SM and CM (SMCM). There was not observed effect (P>0.10) of different protein sources on average daily gain (ADG) between the animals that received multiple supplement as well as difference was notverified for ADG between the multiple supplements and MM. Therefore, cottonseed meal can replace soybean meal or can be used in association to the soybean meal on multiple supplements for lactating beef heifers.