Mastite subclínica bovina: teores de proteína no leite após o tratamento durante a lactação

ABSTRACT The present study assessed the protein fractions of the milk in 135 mammary quarters with subclinical mastitis caused by Staphylococcus aureus. These quarters were classified in two groups: treated (67) and not treated (68). The antimicrobial drug used for the treatment was gentamicin (150 mg) once a day and for three consecutive days. The herd was situated in the Barretos region, state of São Paulo, Brazil. Mammary quarters were considered cured when samples of milk were negative for the isolation of S. aureus 30 days after the treatment. Fractions of total protein, true protein, casein and whey protein were determined, before and after lactation. Total solids, somatic cell counts and milk production were also analyzed. After the analyses of the data, it was verified that there was no significant difference for total protein, true protein or whey protein after the treatment, while the same difference found in sick mammary quarters for casein, before and after the treatment, was verified for the healthy quarters. In conclusion, the treatment of subclinical mastitis caused by S. aureus during lactation did not produce improvement in the quality of the product when the milk protein levels were analyzed.

RESUMO Verificou-se os teores protéicos do leite em 135 quartos mamários com mastite subclínica causada por Staphylococcus aureus divididos em dois grupos, tratados (67) e não tratados (68). Utilizou-se para a tratamento a dose de 150 mg de gentamicina, uma vez ao dia e por três dias consecutivos, em uma propriedade com rebanho leiteiro experimental localizada na região de Barretos, interior do Estado de São Paulo. Foram considerados curados os quartos mamários cujas amostras de leite mostraram-se negativas ao isolamento das cepas de S. aureus 30 dias após o tratamento. Determinou-se as frações de proteína total (PT), proteína verdadeira (PV), caseína (CAS) e soroproteínas (SP), antes e depois do tratamento durante a lactação. As análises do extrato seco total (EST), da contagem de células somáticas (CCS) e da produção de leite também foram efetuadas. Após as análises dos dados, verificou-se que não houve diferença significativa para PT, PV e SP após o tratamento, enquanto a mesma diferença encontrada em quartos mamários doentes para CAS, antes e após o tratamento, também foi verificada para os quartos sadios que serviram de controle. Dessa maneira, concluiu-se que o tratamento da mastite subclínica causada por S. aureus durante a lactação não acarretou melhoria na qualidade do produto quando os itens analisados foram os teores protéicos do leite.

Influência da mastite subclínica bovina sobre as frações protéicas do leite

ABSTRACT The influence of bovine subclinical mastitis caused by Staphylococcus aureus upon the milk protein fractions was evaluated with the comparison among mammary quarters with subclinical mastits and healthy mammary quarters. The trial was performed in a dairy herd with crossbred Holstein cows and the diagnosis of subclinical mastitis was previously made by California Mastitis Test. The milk fractions as total protein, true protein, casein, whey protein, nonprotein nitrogen, noncasein nitrogen, as well as the somatic cell counts (SCC) from milk were determined. The animals were distributed into two groups in conformity to lactational stage. Group 1 included animals between 10 and 60 days in milk and the group 2 included animals between 61 days and ninth month in milk. The infected quarters SCC in the cows from the two groups was higher than healthy mammary quarters (P 0.0001). The whey proteins and the noncasein nitrogen in the milk from mammary quarters with subclinical mastitis caused by S. aureus were significantly higher in the cows above 60 days in milk.

RESUMO Avaliou-se a influência da mastite subclínica bovina causada por Staphylococcus aureus sobre as frações protéicas do leite pela comparação entre quartos mamários doentes e sadios. O estudo foi realizado em propriedade leiteira com rebanho experimental de vacas holandesas e o diagnóstico da mastite subclínica foi previamente realizado pelo California Mastitis Test (CMT). Determinou-se as frações de proteína total, proteína verdadeira, caseína, soroproteínas, nitrogênio não protéico e nitrogênio não caséico, além da contagem de células somáticas (CCS) do leite dos quartos mamários. Os animais selecionados foram distribuídos em dois grupos de acordo com o estágio de lactação e classificados em Grupo 1, composto por animais em estágio inicial de lactação compreendido entre os dez dias e os dois meses após o parto, e Grupo 2, formado por animais em estágio de lactação compreendido entre o início do terceiro mês após o parto até o nono mês de lactação. A CCS dos quartos infectados dos animais pertencentes a ambos os grupos foi superior à encontrada para os quartos sadios (P 0,0001). O conteúdo de soroproteínas e de nitrogênio não caséico no leite de quartos mamários com mastite subclínica por S. aureus foi significativamente superior em animais acima dos 60 dias em lactação, quando comparados com quartos mamários sem mastite.

Performance, carcass yield, and qualitative characteristics of breast and leg muscles of broilers fed diets supplemented with vitamin E at different ages

The effects of vitamin E supplementation (300 mg/kg diet) in the diet of broiler chickens for different periods during rearing on the performance and qualitative traits of breast and leg muscles were evaluated. Seven hundred and twenty day-old chicks were distributed into six treatments: basal diet (25 mg vitamin E/kg diet), and diet supplemented with vitamin E from 1 to 15, 1 to 30, 1 to 45, 14 to 45 and 30 to 45 days of age. Vitamin E content, lipid percentage, TBARS (0 and 3 days of storage), color (*L, *a, *b), and pH were evaluated. There were no differences (p>0.05) among treatments in performance, carcass yield, and cut yields. Qualitative parameters (pH and color) presented no differences, although vitamin E positively affected TBARS values at 3 days of storage, mainly in leg muscles. Vitamin E levels in both muscles were higher in the birds supplemented throughout the experiment.

Performance, carcass yield, and qualitative characteristics of breast and leg muscles of broilers fed diets supplemented with vitamin E at different ages

The effects of vitamin E supplementation (300 mg/kg diet) in the diet of broiler chickens for different periods during rearing on the performance and qualitative traits of breast and leg muscles were evaluated. Seven hundred and twenty day-old chicks were distributed into six treatments: basal diet (25 mg vitamin E/kg diet), and diet supplemented with vitamin E from 1 to 15, 1 to 30, 1 to 45, 14 to 45 and 30 to 45 days of age. Vitamin E content, lipid percentage, TBARS (0 and 3 days of storage), color (*L, *a, *b), and pH were evaluated. There were no differences (p>0.05) among treatments in performance, carcass yield, and cut yields. Qualitative parameters (pH and color) presented no differences, although vitamin E positively affected TBARS values at 3 days of storage, mainly in leg muscles. Vitamin E levels in both muscles were higher in the birds supplemented throughout the experiment.

Effect of deboning time on the quality of broiler breast meat (Pectoralis major)

The present study evaluated the effect of different deboning times on the quality of broiler breast meat. Seventy-two broiler breasts were evaluated. They were distributed in a completely randomized experimental design, with six treatments, six repetitions and two birds per parcel. The treatments were denominated as follows: A - deboning immediately after chilling, B - deboning 1 h after chilling, C - deboning 2 h after chilling, D - deboning 3 h after chilling, E - deboning 4 h after chilling, and F - deboning 24 hours after chilling. Lowest pH values (p 0.05) were seen when deboning was performed 24 h after carcass chilling (pH=6.00) in comparison to deboning at 0 h (6.69) and 1 h (6.42) after chilling. R values were inversely proportional to pH values, i.e., R values were lower (p 0.05) in treatments A (1.05) and B (1.07) when compared to treatment F (1.44). No differences were seen in cooking loss during thermal treatment (broiling) of the muscle P. major. Higher shear forces (p 0.05) were seen in broiled muscles from carcasses with shorter storage times (A - 11.78 kgf and B - 10.75 kgf) before deboning, when compared to treatments E (6.11 kgf) and F (5.64 kgf). Higher L* values were observed in the treatment in which carcass deboning was performed 24 hours after chilling (49.26) in comparison to deboning immediately after chilling (44.68). Therefore, it was concluded that an interval of at least 4 hours is needed between chilling and deboning to obtain broiled breast fillets with tender texture. Furthermore, paler meat color (L* value) was produced with longer carcass storage before deboning.

Carcass and cut yields and meat qualitative traits of broilers fed diets containing probiotics and prebiotics

This study evaluated the use of different probiotics, prebiotics and symbiotics on the quality of carcasses and meat of broiler chickens. One hundred and eight day-old Cobb male broilers were used (n=108) in a completely randomized design according to a 3x3 factorial, with 3 probiotics in the diet (no probiotics, probiotics 1, probiotics 2) and 3 prebiotics in the diet (no prebiotics, prebiotics 1, prebiotics 2). There were nine treatments with 4 replicates and 3 birds per replicate. The results showed that the carcass and cut yields, color (L* - lightness, a* - redness, and b* - yellowness), pH, cooking losses, shearing force and sensory analysis were not affected by the use of different growth promoters at 42 days of age. It was concluded that growth promoters supplemented to the diet did not affect the studied quantitative and qualitative parameters of the carcass and breast meat of broiler chickens.

Carcass and cut yields and meat qualitative traits of broilers fed diets containing probiotics and prebiotics

This study evaluated the use of different probiotics, prebiotics and symbiotics on the quality of carcasses and meat of broiler chickens. One hundred and eight day-old Cobb male broilers were used (n=108) in a completely randomized design according to a 3x3 factorial, with 3 probiotics in the diet (no probiotics, probiotics 1, probiotics 2) and 3 prebiotics in the diet (no prebiotics, prebiotics 1, prebiotics 2). There were nine treatments with 4 replicates and 3 birds per replicate. The results showed that the carcass and cut yields, color (L* - lightness, a* - redness, and b* - yellowness), pH, cooking losses, shearing force and sensory analysis were not affected by the use of different growth promoters at 42 days of age. It was concluded that growth promoters supplemented to the diet did not affect the studied quantitative and qualitative parameters of the carcass and breast meat of broiler chickens.

Effect of deboning time on the quality of broiler breast meat (Pectoralis major)

The present study evaluated the effect of different deboning times on the quality of broiler breast meat. Seventy-two broiler breasts were evaluated. They were distributed in a completely randomized experimental design, with six treatments, six repetitions and two birds per parcel. The treatments were denominated as follows: A - deboning immediately after chilling, B - deboning 1 h after chilling, C - deboning 2 h after chilling, D - deboning 3 h after chilling, E - deboning 4 h after chilling, and F - deboning 24 hours after chilling. Lowest pH values (p 0.05) were seen when deboning was performed 24 h after carcass chilling (pH=6.00) in comparison to deboning at 0 h (6.69) and 1 h (6.42) after chilling. R values were inversely proportional to pH values, i.e., R values were lower (p 0.05) in treatments A (1.05) and B (1.07) when compared to treatment F (1.44). No differences were seen in cooking loss during thermal treatment (broiling) of the muscle P. major. Higher shear forces (p 0.05) were seen in broiled muscles from carcasses with shorter storage times (A - 11.78 kgf and B - 10.75 kgf) before deboning, when compared to treatments E (6.11 kgf) and F (5.64 kgf). Higher L* values were observed in the treatment in which carcass deboning was performed 24 hours after chilling (49.26) in comparison to deboning immediately after chilling (44.68). Therefore, it was concluded that an interval of at least 4 hours is needed between chilling and deboning to obtain broiled breast fillets with tender texture. Furthermore, paler meat color (L* value) was produced with longer carcass storage before deboning.

Performance of broilers fed diets containing natural growth promoters

The present study evaluated the effect of different probiotics on the performance of broiler chickens. A thousand and fifty one-day-old male Cobb chicks were distributed in a completely randomized design in a 3 x 2 + 1 factorial arrangement (3 probiotics sources in the diet, 2 probiotics concentrations in drinking water and 1 control group), with 5 repetitions of 30 birds per parcel. The results showed better feed conversion (p 0.01) (1-21, 22-35 and 1-45 days) and weight gain (p 0.05) (22-35 and 1-45 days) in the control group in relation to the groups receiving probiotics. The use of Bacillus subtilis in the diet improved (p 0.05) feed conversion during the growing phase, but this was not seen in the following period. Thus, it was concluded that probiotics supplementation had no beneficial effects on the performance.

Performance of broilers fed diets containing natural growth promoters

The present study evaluated the effect of different probiotics on the performance of broiler chickens. A thousand and fifty one-day-old male Cobb chicks were distributed in a completely randomized design in a 3 x 2 + 1 factorial arrangement (3 probiotics sources in the diet, 2 probiotics concentrations in drinking water and 1 control group), with 5 repetitions of 30 birds per parcel. The results showed better feed conversion (p 0.01) (1-21, 22-35 and 1-45 days) and weight gain (p 0.05) (22-35 and 1-45 days) in the control group in relation to the groups receiving probiotics. The use of Bacillus subtilis in the diet improved (p 0.05) feed conversion during the growing phase, but this was not seen in the following period. Thus, it was concluded that probiotics supplementation had no beneficial effects on the performance.

Effect of different probiotics on broiler carcass and meat quality

The present work evaluated the effect of different probiotics on carcass and meat quality of broilers. One thousand and fifty male Cobb chicks were distributed at one day of age in a randomized design with 3 x 2 + 1 factorial arrangement (3 probiotics, 2 levels of probiotics in drinking water and 1 negative control group), using 5 replications with 30 birds. Carcass yield was higher (p 0.05) in control birds. Nevertheless, the groups fed with probiotics showed higher (p 0.01) leg yield at 45 days of age. There was a significant decrease in color (lightness) and increase in pH of breast muscle 5 hours after slaughter in the probiotics treated birds. In the sensory analysis, meat flavor and general aspect 72 hours after slaughter were better when probiotics were added in both water and diet. There were no differences in water holding capacity, cooking loss and shearing force among different probiotics or between them and the control. Thus, meat quality was better when probiotics were fed in the water and diet instead of only in the diet. Nevertheless, carcass and meat quality showed no alteration when the control group was compared to birds fed with probiotics, except for leg yield improvement in the latter.

Effect of different probiotics on broiler carcass and meat quality

The present work evaluated the effect of different probiotics on carcass and meat quality of broilers. One thousand and fifty male Cobb chicks were distributed at one day of age in a randomized design with 3 x 2 + 1 factorial arrangement (3 probiotics, 2 levels of probiotics in drinking water and 1 negative control group), using 5 replications with 30 birds. Carcass yield was higher (p 0.05) in control birds. Nevertheless, the groups fed with probiotics showed higher (p 0.01) leg yield at 45 days of age. There was a significant decrease in color (lightness) and increase in pH of breast muscle 5 hours after slaughter in the probiotics treated birds. In the sensory analysis, meat flavor and general aspect 72 hours after slaughter were better when probiotics were added in both water and diet. There were no differences in water holding capacity, cooking loss and shearing force among different probiotics or between them and the control. Thus, meat quality was better when probiotics were fed in the water and diet instead of only in the diet. Nevertheless, carcass and meat quality showed no alteration when the control group was compared to birds fed with probiotics, except for leg yield improvement in the latter.