Renata Helena Branco

Suplementação de lipídios em dietas para cabras em lactação: consumo e eficiência de utilização de nutrientes

The effect of different fat supplements on intake, digestibility, nitrogen balance, milk yield and efficiency of nutrient utilization was evaluated in lactating dairy goats. Twenty-four dairy goats were assigned to a completely randomized design with four treatments and six replicates/treatment. The fat supplements tested were soybean oil (SO), calcium salts of longchain fatty acids (CS) and whole soybean (WS), which contributed with 4.5% of dietary ether extract. A control diet with no added fat was also fed to the animals. Daily measurements of intake and milk yield were done from day 51 to day 138 of lactation. Intakes of DM (DMI), NDF (NDFI), TDN (TDNI), and net energy (NEI) were lower on soybean oil and whole soybean than on control and CS diets. Feeding fat supplements to lactating goats reduced digestibilities of OM, CP and TC. Digestibility of NDF was reduced by SO while that of NFC was reduced by WS. Yields of milk fat, milk protein and milk decreased when WS was fed and the feeding of all three fat supplements depressed the yield of milk lactose. No significant differences in the concentration of milk components were observed across treatments. Similarly, the net efficiency of utilization of ingested metabolizable energy for milk production (kl) did not differ among diets. The same was true for nitrogen balance and retained nitrogen.The effect of different fat supplements on intake, digestibility, nitrogen balance, milk yield and efficiency of nutrient utilization was evaluated in lactating dairy goats. Twenty-four dairy goats were assigned to a completely randomized design with four treatments and six replicates/treatment. The fat supplements tested were soybean oil (SO), calcium salts of long-chain fatty acids (CS) and whole soybean (WS), which contributed with 4.5% of dietary ether extract. A control diet with no added fat was also fed to the animals. Daily measurements of intake and milk yield were done from day 51 to day 138 of lactation. Intakes of DM (DMI), NDF (NDFI), TDN (TDNI), and net energy (NEI) were lower on soybean oil and whole soybean than on control and CS diets. Feeding fat supplements to lactating goats reduced digestibilities of OM, CP and TC. Digestibility of NDF was reduced by SO while that of NFC was reduced by WS. Yields of milk fat, milk protein and milk decreased when WS was fed and the feeding of all three fat supplements depressed the yield of milk lactose. No significant differences in the concentration of milk components were observed across treatments. Similarly, the net efficiency of utilization of ingested metabolizable energy for milk production (kl) did not differ among diets. The same was true for nitrogen balance and retained nitrogen.

Comportamento ingestivo de cabras Alpinas em lactação alimentadas com dietas contendo diferentes níveis de fibra em detergente neutro proveniente da forragem

Avaliou-se o efeito de diferentes niveis de fibra em detergente neutro proveniente da forragem (FDNF) na dieta sobre o comportamento ingestivo de cabras em lactacao. Cinquenta cabras da raca Alpina foram distribuidas em um delineamento inteiramente casualizado, com cinco tratamentos e dez repeticoes, sendo alimentadas a vontade com dietas contendo 20, 27, 34, 41 ou 48% de FDNF. Foi utilizada uma racao completa com feno de tifton-85 (Cynodon sp.) + mistura concentrada constituida de fuba de milho (Zea mays L.), farelo de soja (Glycine max L.) e mistura mineral. As dietas foram fornecidas duas vezes ao dia, as 8h30 e 16h30. O comportamento ingestivo foi determinado mediante observacao visual individual dos animais, durante 24 horas, a intervalos de 10 minutos para se determinar o tempo despendido em alimentacao, ruminacao e ocio. O tempo com alimentacao e ruminacao e o tempo de mastigacao total aumentaram linearmente, enquanto o tempo de ocio diminuiu linearmente com o aumento do nivel de FDNF nas dietas. Observaram-se efeitos linear decrescente na eficiencia de alimentacao e ruminacao (g MS/h) e linear crescente no numero diario de refeicoes, conforme amumentaram os niveis de FDNF.

Efeito da suplementação de lipídios sobre a digestibilidade e os parâmetros da fermentação ruminal em cabras leiteiras

Eight non-pregnant, non-lactating dairy goats fitted with ruminal cannulas were assigned to two replicated 4 x 4 Latin squares to evaluate the effects of lipid supplementation on intake, total tract and ruminal digestibility of nutrients, ruminal metabolism, and microbial protein synthesis. Animals were fed a control diet (no fat supplementation; 2.0% ether extract) or a diet supplemented (4.5% of added ether extract) with soybean oil (SO), calcium salts of long-chain fatty acids (CS) or whole soybean grain (WS). No significant differences were observed for dry matter intake among diets. Apparent total tract and ruminal digestibilities of ether extract were greater on diets containing fat supplements than on the control diet. The greatest ruminal retention time of particles was observed in the WS diet. Fat supplementation did not affect ruminal pH and microbial protein synthesis and efficiency but reduced the concentration of ruminal ammonia. Based on these results, it is recommended the addition of up to 4.5% of fat in diets of non-lactating dairy goats.

Consumo de nutrientes, produção e composição do leite de cabras da raça Alpina alimentadas com dietas contendo diferentes teores de fibra

Fifty Alpine lactating does were used to evaluate the effects of feeding different levels of forage neutral detergent fiber (FNDF) on nutrient intake and milk yield and composition. Animals were housed individually and assigned to a completely randomized design with five treatments and ten replicates. A total mixed ration, containing Tifton-85 (Cynodon sp.) hay, ground corn, soybean meal and mineral mixture was fed ad libitum. The experimental diets contained 20, 27, 34, 41 or 48% of FNDF. As dietary FNDF increased, the intakes of DM, OM, CP, EE, TC, NSC and net energy (NE) decreased linearly. In addition, increasing dietary FNDF linearly increased intakes of NDF, FNDF and ADF. There was no effect of FNDF level on contents of milk fat and milk total solids. However, milk yield, fat-corrected milk and yield of total solids all decreased linearly. The efficiency of utilization of metabolizable energy to milk yield reached a plateau at 35.4% of FNDF.

Avaliação do consumo e de metabólitos plasmáticos de cabras gestantes com duas condições corporais alimentadas com dietas formuladas com diferentes níveis de energia

The present study evaluated the relationship between different dietary net energy (NE) levels and body condition score (BCS) on performance of dairy goats during the prepartum period. Forty-eight pregnant goats were kept in individual cages during the last 30 days before parturition. The experimental design was a completely randomized design with a 2 x 3 factorial arrangement of treatments (two BCS and three levels of NE in the diet). Goats were assigned to one of two groups, based on body condition score, which was either 3.25 or below. Prepartum diets contained 1.1, 1.4 or 1.6 Mcal NE/kg DM and 13% of CP. Blood samples were collected weekly beginning 21 days before parturition and plasma analyzed for concentration of nonesterified fatty acids (NEFA). Intakes of DM and NDF were lower in animals with greater BCS. However, intakes of DM and NE paralleled the increment of energy in the diet while the opposite was observed for NDF intake. As expected, feeding goats the low NE diet increased the plasma concentration of NEFA at day -14 and at parturition.

Genomic Regions Associated with Feed Efficiency Indicator Traits in an Experimental Nellore Cattle Population

The objective of this study was to identify genomic regions and metabolic pathways associated with dry matter intake, average daily gain, feed efficiency and residual feed intake in an experimental Nellore cattle population. The high-density SNP chip (Illumina High-Density Bovine BeadChip, 777k) was used to genotype the animals. The SNP markers effects and their variances were estimated using the single-step genome wide association method. The (co)variance components were estimated by Bayesian inference. The chromosome segments that are responsible for more than 1.0% of additive genetic variance were selected to explore and determine possible quantitative trait loci. The bovine genome Map Viewer was used to identify genes. In total, 51 genomic regions were identified for all analyzed traits. The heritability estimated for feed efficiency was low magnitude (0.13±0.06). For average daily gain, dry matter intake and residual feed intake, heritability was moderate to high (0.43±0.05; 0.47±0.05, 0.18±0.05, respectively). A total of 8, 17, 14 and 12 windows that are responsible for more than 1% of the additive genetic variance for dry matter intake, average daily gain, feed efficiency and residual feed intake, respectively, were identified. Candidate genes GOLIM4, RFX6, CACNG7, CACNG6, CAPN8, CAPN2, AKT2, GPRC6A, and GPR45 were associated with feed efficiency traits. It was expected that the response to selection would be higher for residual feed intake than for feed efficiency. Genomic regions harboring possible QTL for feed efficiency indicator traits were identified. Candidate genes identified are involved in energy use, metabolism protein, ion transport, transmembrane transport, the olfactory system, the immune system, secretion and cellular activity. The identification of these regions and their respective candidate genes should contribute to the formation of a genetic basis in Nellore cattle for feed efficiency indicator traits, and these results would support the selection for these traits.

Relationship between residual feed intake and enteric methane emission in Nellore cattle

Feed intake and average daily gain (ADG) in Nellore cattle were determined to calculate residual feed intake in two performance tests: first during the growth phase (RFIgrowth) and then during a measurement of the methane emission phase (RFImet). During the RFIgrowth test, 62 males and 56 females were classified as low-, medium-, and high-RFI. Enteric methane emission was measured in 46 animals; 23 males used for RFImet measurement plus 23 females (22 low-RFIgrowth and 24 high-RFIgrowth). Diet consisted of Brachiaria brizantha cv. Marandu hay (445 g/kg DM) and concentrate (555 g/kg DM). During the RFIgrowth and RFImet phases, DMI was lower in the animals with low RFI, with no difference in ADG. Residual feed intake was -0.359 and 0.367 kg DM/d for low- and high-RFI animals. Enteric methane emission (g/d, g/kg BW0.75 and g/kg ADG) did not differ between RFIgrowth classes. Enteric methane emission (g/d) was higher in high RFImet and lower in low RFImet males. Spearman correlations among traits obtained during both tests, which were high between metabolic BW (r = 0.959) and between DMI (r = 0.718), and zero between ADG (r = -0.062), resulted in moderate correlation between RFIgrowth and RFImet (r = 0.412). However, it is not possible to confirm that high-efficiency animals release less enteric methane, since different results were obtained when enteric methane was compared between the RFIgrowth and RFImet classes.

Desempenho de cabras em lactação alimentadas com dietas com diferentes níveis de fibra oriundas de forragem com maturidade avançada

Objetivou-se com este trabalho avaliar o efeito de diferentes teores de fibra em detergente neutro oriunda da forragem com maturidade avancada sobre o consumo, a digestibilidade da materia seca e de nutrientes, o balanco de nitrogenio, a producao de leite, a eficiencia de utilizacao da energia metabolizavel e o comportamento ingestivo de cabras em lactacao. Foram distribuidas cinco cabras em delineamento em quadrado latino 5 × 5 utilizando-se teores crescentes de fibra em detergente neutro oriunda da forragem como variavel independente. As concentracoes de fibra em detergente neutro oriunda da foragem utilizadas foram 20, 28, 35, 43 e 49%. Os consumos de materia seca, de nutrientes e de energia liquida reduziram com o aumento de fibra na racao. No entanto, o consumo de fibra em detergente foi crescente, indicando capacidade de acomodacao desse componente nutritivo pelos animais. O teor de fibra influenciou os coeficientes de digestibilidade da materia seca, materia orgânica, proteina bruta e dos carboidratos nao-fibrosos, contudo, a digestibilidade da fibra em detergente neutro nao foi influenciada pelas dietas. O nivel de fibra em detergente neutro oriunda da forragem nao influenciou os constituintes do leite (gordura, proteina e lactose). O teor de fibra oriunda da forragem teve efeito quadratico sobre a producao de leite (corrigida e nao corrigida para 4% de gordura), em kg/dia, com maiores producoes obtidas com o teor de 28% de fibra. A eficiencia de utilizacao da energia metabolizavel nao foi influenciada pelas variacoes nas dietas. O teor de fibra em detergente neutro oriunda da forragem influencia o comportamento ingestivo de cabras em lactacao, aumentando os tempos de ruminacao e mastigacao e diminuindo o tempo em ocio dos animais.

Consumo, digestibilidade e produção de leite de cabras leiteiras alimentadas com dietas contendo diferentes níveis de proteína bruta e energia líquida

Intake, digestibility of dry matter and nutrients, milk production and composition were evaluated with four isoenergetic diets containing 1.53 Mcal of net energy/kg DM and 11.4, 16.5, 19.5, and 22.6% CP. The effect of energy and PB levels were evaluated by considering the ratio of protein content and net energy concentration of the diets, obtaining values of 7.3, 10.8, 12.9, and 14.8. Eight goats were assigned to two 4 x 4 latin square design. The experimental period lasted 21 days, with 14 days for adaptation of animals and seven days for samplings. Higher DM intakes were obtained with diets with CP/NE ratio different from 7.3. The supply of the diets with lower CP/NE ratios resulted in higher intakes of NFC and EE and and reduction in TDN and NE intakes. Apparent digestibility of NFC and NDF were not altered. Higher digestibility of EE was observed when lower CP/NE ratio was used. CP digestibility decreased with the supply of diet with lower CP/NE ratio (7.3), probably due to the addition to the diet of nitrogen sources of high ruminal degradability (urea). DM digestibility differed when compared to the extreme levels of CP/NE ratio and lower in the CP/NE ratio of 7.3. Higher milk production was observed when compare 14.8 CP/NE ratio with 7.32 and 10.8 CP/NE ratio and no alteration occurred for milk components. Higher efficiency of consumed DM was obtained with diet with higher CP/NE ratio, whereas, the efficiency of N utilization in milk in relation to N intake was reduced in inverse way.

Use of high moisture corn silage replacing dry corn on intake, apparent digestibility, production and composition of milk of dairy goats

Twenty primiparous and multiparous Alpine breed goats at approximately 80 days of lactation were used in this experiment. The animals were housed individually in metal cages and distributed according to milk production in five 4 × 4 Latin squares. The experimental diets used in the experiment presented concentrate:forage ratio of 65:35. The treatments were characterized by increasing levels of 0, 33, 67 and 100% of high moisture corn silage (HMCS) replacing corn dry grain (CDG). Average intake of DM (1.62 kg/day, 3.90 % BW), CP (0.22 kg/day), NFC (0.76 kg/day) and TDN (1.29 kg/day) were not influenced by levels of HMCS. However, intake of NDF (0.53 kg/day) was significant for the different level of HMCS. Daily milk production and production of milk correct at 3.5% of fat, feed efficiency (MP/DMI), fat percentage, protein, lactose, total solids and milk urea nitrogen, with means of 1.86; 1.69; 1.11; 2.96; 2.85; 4.36; 10.96 and 17.1, respectively, were not influenced by the levels of HMCS. Percentage of non fat solids (8.00%) was affected by replacing levels of HMCS. The use of high moisture corn silage in the diet does not change milk production and it can be applied in total or partial substitution to dry corn grain in the feeding of milk goats.