Francisco Palma Rennó

Effect of the kappa-casein gene polymorphism, breed and seasonality on physicochemical characteristics, composition and stability of bovine milk

The objective of this study was to evaluate the effect of genetic polymorphism of kappa-casein, breed and seasonality on the physicochemical characteristics, composition and stability of milk in commercial dairy herds. A total of 879 milk and blood samples were collected from 603 Holstein and 276 Girolando cows, obtained during rainy and dry seasons. Milk samples were analyzed to determine the physicochemical characteristics, composition and ethanol stability, while blood samples were subjected to polymerase chain reaction to identify the kappa-casein genotype. The frequencies of genotypes AA, AB and BB of k-casein were respectively, 66.83, 31.84 and 1.33% for Holstein, and 71.38, 27.90 and 0.72% for the Girolando cows, respectively. The A allele was more frequent than the B allele, both for Holstein (0.827 and 0.173) and Girolando cows (0.853 and 0.147), respectively. Cows of AB and BB genotypes showed a higher milk fat content compared to the AA genotype. There was an interaction between breed and seasonality on the concentration of milk urea with higher values for Holstein and Girolando cows in the rainy and dry season, respectively. The levels of lactose, total solids, crude protein, true protein, casein and the casein:true protein ratio were higher during the dry season, while during the rainy season, the somatic cell count and milk urea concentration were higher. There was no association between milk stability and k-casein genotypes, but Holstein cows showed higher milk stability than Girolando cows, and milk was more stable during the rainy season than during the dry season.

Utilização de óleo de soja em rações para vacas leiteiras no período de transição: consumo, produção e composição do leite

O objetivo neste estudo foi avaliar o desempenho produtivo de vacas leiteiras sob suplementacao com oleo de soja durante o periodo de transicao. Foram utilizadas 20 vacas da raca Holandesa, multiparas e gestantes, distribuidas aleatoriamente em duas racoes: controle, com 2,5% de extrato etereo (EE) na materia seca (MS); e gordura, com adicao de 3,0% de oleo de soja e 5,5% de EE na MS. Os valores medios de consumo de MS e nutrientes nao diferiram no periodo pre e pos-parto nas vacas das dietas controle e com oleo de soja, exceto no maior consumo de EE, em decorrencia da maior concentracao desse nutriente na dieta com oleo. Em virtude da maior densidade energetica da racao com oleo de soja, as vacas apresentaram maior consumo de nutrientes digestiveis totais e energia liquida no pos-parto. Nao foi observada alteracao nas producoes de leite e gordura, no entanto, observou-se reducao do teor de gordura do leite nas vacas da racao com oleo de soja em relacao aquelas da racao controle. As racoes utilizadas nao influenciaram o consumo, mas a dieta com oleo de soja aumentou a ingestao de energia liquida e melhorou o balanco de nutrientes no inicio da lactacao. Foi observado aumento nao-significativo (+ 2,53 kg/dia) na producao de leite das vacas da dieta com oleo de soja.

Equine chorionic gonadotropin alters luteal cell morphologic features related to progesterone synthesis

Exogenous eCG for stimulation of a single dominant follicle or for superovulation are common strategies to improve reproductive efficiency by increasing pregnancy rates and embryo production, respectively. Morphofunctional changes in the CL of eCG-treated cattle include increases in CL volume and plasma progesterone concentrations. Therefore, we tested the hypothesis that eCG alters the content of luteal cells and mitochondria related to hormone production. Twelve crossbred beef cows were synchronized and then allocated into three groups (four cows per group) and received no further treatment (control) or were given eCG either before or after follicular deviation (superovulation and stimulation of the dominant follicle, respectively). Six days after ovulation, cows were slaughtered and CL collected for morphohistologic and ultrastructural analysis. Mitochondrial volume per CL was highest in superovulated followed by stimulated and then control cows (18,500 ± 2630, 12,300 ± 2640, and 7670 ± 3400 μm(3); P < 0.001), and the density of spherical mitochondria and the total number of large luteal cells were increased (P < 0.05) in stimulated cows compared with the other two groups (110.32 ± 14.22, 72.26 ± 8.77, and 70.46 ± 9.58 mitochondria per μm(3) and 678 ± 147, 245 ± 199, and 346 ± 38 × 10(6) cells, respectively. However, the largest diameters of the large luteal cells were increased in superovulated and control cows versus stimulated ones (32.32 ± 0.06, 31.59 ± 0.81, and 29.44 ± 0.77 μm; P < 0.0001). In contrast, the total number of small luteal cells was increased in superovulated cows (1456 ± 268, 492 ± 181, and 822 ± 461 × 10(6), P < 0.05). In conclusion, there were indications of cellular changes related to increased hormonal production (stimulatory treatment) and increased CL volume (superovulatory treatment).

Productive performance and composition of milk protein fraction in dairy cows supplemented with fat sources.

The objective of this study was to evaluate the use of fat sources in rations for lactating cows on the productive performance and composition of milk protein fraction. Twelve Holstein cows were used, grouped in three balanced 4 × 4 Latin squares, fed with the following rations: control; refined soybean oil; whole raw soybean; and calcium salts of unsaturated fatty acid (Megalac-E). Dry matter and nutrient intake, and daily milk production were evaluated. The samples used to analyze milk composition were collected in two alternate days and were obtained from two daily milking. Milk composition and total nitrogen, non-protein nitrogen and non-casein nitrogen ratios were analyzed. The casein, serum protein and true protein ratios were obtained by difference. Dry matter and nutrient intakes were lower when cows received the diet containing calcium salts of fatty acids, in relation to the control diet. Among the diets with fat sources, the one with whole raw soybean and calcium salts decreased milk production. There was no effect of fat sources added to the diet on crude protein, non-protein nitrogen, non-casein nitrogen, true protein, casein, casein/milk true protein ratio and serum protein. Similarly, the experimental diets did not influence the protein fractions when expressed in percentage of milk crude protein. The utilization of fat sources in diets changes milk production and composition of lactating cows, but does not influence the composition of milk protein fractions.

Níveis de uréia na ração de novilhos de quatro grupos genéticos: consumo e digestibilidades totais

The effects of diet adaptation protocol by steers and of feeding four dietary urea levels (0, 0.65, 1.3, and 1.95%, dry matter - DM basis) on intake and total apparent digestibility of DM, organic matter (OM), crude protein (CP), ether extract (EE), total carbohydrates (CHO), neutral detergent fiber (NDF), nonfiber carbohydrates (NFC) and total digestible nutrients intake (TDN) for Holstein, ½ Holstein-Guzera, ½ Holstein-Gir and Zebu steers were evaluated in this trial. The animals were assigned to four 4x4 latin squares (genetic groups): four animals, four experimental periods and four treatments (diets). The animals were fed diets (12% CP, with increasing urea levels) with 50% tifton-85 bermudagrass hay and concentrate. The first experimental period lasted 19 days, 13 days for adaptation and 6 days for feces collection. The possibility of reducing diet adaptation in the subsequent periods was investigated by evaluating daily DM intake in the adaptation period. The indigestible acid detergent fiber (FDAi) was used as marker of fecal dry matter flow. The adaptation to diets of the subsequent experimental periods was reduced by 10 days, because DM intake means, for each urea level, from 1st to 12th day of adaptation did not differ from the standard mean (13th day). The intake, expressed as kg/day, was higher for Holstein animals, followed by the crossbreds and Zebu. Total DM digestibility was affected nor by the genetic groups, neither by the dietary urea levels.

Desempenho e parâmetros sanguíneos de vacas leiteiras alimentadas com grão de soja

The editorial process of Archivos de Zootecnia during 2012 is reported below. A total of 361 manuscripts coming from 28 countries, mainly from Brazil (78 %), were received. Consequently, the language most frequently used in the manuscripts was Portuguese, followed by Spanish and English. The mean time elapsed from submission of a manuscript until printing, was 599 days, a hundred days shorter than 2011. The rejection rate was 65 %. In 2011, 53 articles, 11 short notes and 7 reviews (total 72) were published by authors coming from 14 different countries.

Total tract nutrient digestion and milk fatty acid profile of dairy cows fed diets containing different levels of whole raw soya beans

Whole oilseeds such as soya beans have been utilized in dairy rations to supply additional fat and protein. However, antinutritional components contained in soya beans, such as trypsin inhibitors and haemagglutinins (lectins) may alter digestibility of nutrients and consequently affect animal performance. The objective of the present experiment was to quantify the effect of different levels of whole raw soya beans in diets of dairy cows on nutrient intake, total tract digestion, nutrient balances and milk yield and composition. Sixteen mid to late-lactation cows (228 ± 20 days in milk; mean ± SD) were used in four replicated 4 × 4 Latin square design experiment with 21-d periods. Cows were assigned to each square according to milk yield and DIM. The animals were randomly allocated to treatments: control (without soya beans addition; CO), WS9, WS18 and WS27, with addition of 9%, 18% and 27% of whole raw soya bean in diet on a dry matter (DM) basis respectively. All diets contained identical forage and concentrate components and consisted of maize silage and concentrate based on ground corn and soya beans at a ratio of 60:40. There were no differences in OM, CP, NDF and NEL intakes (kg/day and MJ/day) among the treatments (p > 0.05). However, DM and NFC intakes were negatively affected (p = 0.04 and p < 0.01, respectively) and ether extract (EE) intake was positively affected (p < 0.01). Total tract digestion increased linearly with whole raw soya beans for EE (p < 0.01) and NDF (p = 0.01). The excretion (kg/day) of digested soya beans grains increased linearly according to addition of whole raw soya beans. However, the nutritive characteristics of excreted grains were not altered. Milk (kg), milk lactose (kg) and protein (kg) yield decreased linearly (p < 0.01, p < 0.01 and p = 0.04, respectively) milk fat content (%) increased linearly (p < 0.01) with whole raw soya beans inclusion. Increasing addition of whole raw soya beans affected milk fatty acid profile with a linear decrease of cis-9-trans 11CLA and total saturated FA; and linear increase of total unsaturated and C18:3 FA. Energy balance was positively affected (p = 0.03) by whole raw soya beans as well as efficiency of NEL milk/DE intake (p = 0.02). Nitrogen balance and microbial protein synthesis were not affected by whole raw soya beans. Increasing doses of whole raw soya beans decreased dry matter intake and milk yield, however, led to an increase of unsaturated acids in milk and higher milk fat concentration.

Global gene expression in the bovine corpus luteum is altered after stimulatory and superovulatory treatments.

Equine chorionic gonadotrophin (eCG) has been widely used in superovulation and artificial insemination programmes and usually promotes an increase in corpus luteum (CL) volume and stimulates progesterone production. Therefore, to identify eCG-regulated genes in the bovine CL, the transcriptome was evaluated by microarray analysis and the expression of selected genes was validated by qPCR and western blot. Eighteen Nelore crossbred cows were divided into control (n=5), stimulated (n=6) and superovulated groups (n=7). Ovulation was synchronised using a progesterone device-based protocol. Stimulated animals received 400 IU of eCG at device removal and superovulated animals received 2000 IU of eCG 4 days prior. Corpora lutea were collected 7 days after gonadotrophin-releasing hormone administration. Overall, 242 transcripts were upregulated and 111 transcripts were downregulated in stimulated cows (P ≤ 0.05) and 111 were upregulated and 113 downregulated in superovulated cows compared to the control animals (1.5-fold, P ≤ 0.05). Among the differentially expressed genes, many were involved in lipid biosynthesis and progesterone production, such as PPARG, STAR, prolactin receptors and follistatin. In conclusion, eCG modulates gene expression differently depending on the treatment, i.e. stimulatory or superovulatory. Our data contribute to the understanding of the pathways involved in increased progesterone levels observed after eCG treatment.

Níveis de uréia na ração de novilhos de quatro grupos genéticos: estimativa da produção de proteína microbiana por meio dos derivados de purinas na urina utilizando duas metodologias de coleta

Objetivou-se avaliar o efeito de quatro niveis de ureia na racao: 0; 0,65; 1,3 e 1,95% na materia seca (MS), sobre a estimativa da producao de proteina microbiana por meio dos derivados de purinas na urina, em duas metodologias de coleta em novilhos de quatro grupos geneticos: Holandes, ½ sangue Holandes-Guzera, ½ sangue Holandes-Gir e Zebu. Os animais foram alimentados com 50% de feno de capim tifton-85 e 50% de concentrado e distribuidos em quatro quadrados latinos (grupos geneticos) 4 ´ 4, sendo quatro animais, quatro periodos experimentais e quatro tratamentos (racoes). As dietas continham aproximadamente 12% PB. As amostras de urina, em cada periodo experimental, foram obtidas a partir de coletas em 24 horas e por meio da coleta spot de urina, quando os animais urinaram espontaneamente. Na urina foram realizadas as analises dos derivados de purinas, alantoina e acido urico. Foram feitas comparacoes entre a producao microbiana usando as bases purinas no abomaso com os derivados de purinas na urina; entre as determinacoes da producao microbiana pelos derivados de purinas com duas equacoes distintas ou com as bases purinas no abomaso; e entre a estimativa da producao urinaria, dos derivados de purinas e da producao microbiana atraves da coleta spot de urina com a coleta total de urina em 24 horas. A producao e as eficiencias microbianas mostraram-se superiores para os animais holandeses, intermediarias para os mesticos e inferiores para os zebuinos. A estimativa da producao de compostos nitrogenados microbianos pode ser feita a partir da excrecao dos derivados de purinas na urina. A coleta spot de urina consiste em metodologia rapida e eficaz na estimativa da excrecao urinaria dos derivados de purinas e da producao de compostos nitrogenados microbianos.

Níveis de uréia na ração de novilhos de quatro grupos genéticos: parâmetros ruminais, uréia plasmática e excreções de uréia e creatinina

Objetivou-se avaliar o efeito de quatro niveis de ureia na racao (0; 0,65; 1,3 e 1,95% na materia seca - MS) sobre pH e amonia ruminais, concentracao plasmatica de ureia, excrecao fracional de ureia e excrecoes de ureia e creatinina, bem como avaliar as perdas urinarias endogenas por meio da excrecao de creatinina em novilhos de quatro grupos geneticos (Holandes, ½ sangue Holandes-Guzera, ½ sangue Holandes-Gir e Zebu). Os animais foram distribuidos em quatro quadrados latinos (grupos geneticos) 4 ´ 4, sendo quatro animais, quatro periodos experimentais de 14 dias cada um e quatro tratamentos (racoes). As coletas de liquido ruminal, para determinacao do pH e das concentracoes de nitrogenio amoniacal (N-NH3), foram realizadas antes do fornecimento da dieta e 2, 4, 6 e 8 horas apos. Durante a coleta de urina realizada em 24 horas, foi coletado o sangue aproximadamente 4 horas apos a alimentacao e, apos centrifugacao, obtido o plasma. Nas amostras de urina e plasma, foram determinadas as concentracoes de ureia e creatinina. O pH ruminal apresentou comportamento semelhante para os grupos geneticos e foi influenciado positivamente pela inclusao de ureia na dieta. As concentracoes de N-NH3 foram influenciadas positivamente pelos niveis de ureia na racao para os animais holandeses e mesticos. A concentracao plasmatica de N-ureico aumentou linearmente em funcao da adicao de ureia na racao. A excrecao fracional de ureia apresentou comportamento linear decrescente em funcao dos niveis de ureia na dieta. A excrecao urinaria de ureia nao diferiu entre os animais holandeses e mesticos, mas foi superior em relacao aos zebuinos. A excrecao de creatinina nao foi influenciada pelos grupos geneticos, nem pela inclusao de ureia na dieta, apresentando valor medio de 27,76 mg/kg PV. Sugere-se que as perdas urinarias endogenas de compostos nitrogenados sejam estimadas a partir da excrecao de creatinina.