H.G. Monardes

Variation in the N -acetyl neuraminic acid content of bovine κ-casein

A total of 555 milk samples was collected from 53 Holstein cows for 1 year. Samples were analysed for N -acetyl neuraminic acid (NANA) content, κ-casein content and somatic cell count. The extent of glycosylation of κ-casein was estimated through the NANA content of κ-casein in each milk sample. The overall mean value for the NANA content was 63·6 ± 20 μg/mg of κ-casein with a range of 23–166 μg/mg. Least squares analysis showed significant ( P

Effect of κ-casein glycosylation on cheese yielding capacity and coagulating properties of milk

Abstract The effects of the average degree of glycosylation of milk κ-casein on rennetclotting time, rate of curd firming and curd firmness 30 min after the addition of chymosin were measured on 55 blended-milks by a Formagraph. The degree of glycosylation, which is reflected by the N-acetylneuraminic content of κ-casein ( NANA κ-CN ) varied from 43 to 93 μg/mg of κ-CN during the study. Significant (p NANA κ-CN ratio were observed, suggesting that a firmer curd can be obtained with milk having a high NANA κ-CN value. To study the effect of the degree of glycosylation of κ-casein on cheese yielding capacity, laboratory-scale Cheddar-type cheese was prepared from 45 blended-milks. No significant (p > 0·1) difference in the 37% moisture-adjusted cheese yield was observed. It is concluded that the improvement of the coagulating properties of milk brought about by the increase in the average degree of glycosylation of κ-casein did not result in a greater cheese yield.

Sólidos totais do leite em amostras de tanque nos estados do Paraná, Santa Catarina e São Paulo

Objetivou-se, neste trabalho, estudar a variacao dos solidos totais em amostras de leite de tanques de 32.590 rebanhos dos estados do Parana, Santa Catarina e Sao Paulo. Foram analisadas 257.540 amostras de leite de tanques coletadas entre janeiro de 1999 e novembro de 2001, no Laboratorio Central do Programa de Analise de Rebanhos Leiteiros do Parana (PARLPR), da Associacao Paranaense de Criadores de Bovinos da Raca Holandesa. Utilizando-se o metodo dos quadrados minimos, foram estudados os efeitos de rebanho, regiao, mes e ano de analise, idade da amostra e escore de celulas somaticas sobre os solidos totais, em amostras de leite de tanques. As medias ajustadas dos solidos totais por regiao variaram de 11,78 a 12,83%; a maior media foi verificada em maio de 2001 e a menor, em janeiro de 2000; os solidos totais nao demonstraram variacao ate o quinto dia de analise; o efeito de escore de celulas somaticas foi contraditorio, se comparado aos relatados por outros autores. Todos os fatores incluidos no modelo linear foram altamente significativos sobre as caracteristicas analisadas. O coeficiente de correlacao entre solidos totais e seus componentes foi de 0,875 para gordura, 0,653 para proteina, 0,237 para lactose, e 0,643 para solidos nao-gordurosos. A correlacao de solidos totais com contagem de celulas somaticas foi 0,012, e com escore de celulas somaticas, de 0,023.

Milk and fat production of crossbred Holstein-Gir cows (Bos taurus taurus-Bos taurus indicus) in the agreste region of the Brazilian state of Pernambuco

The productive performance of four Holstein-Gir genetic groups (1/2H, 1/4H, 5/8H, 5/8Hinter se) and the effects of non-genetic factors on production traits was evaluated using a data set of 7,951 test-day samples collected between January 1980 and December 1999 from the Arcoverde Experimental Station in the Brazilian state of Pernambuco (Empresa Pernambucana de Pesquisa Agropecuaria). The statistical model included the fixed effects of calving year (1980 to 1999) and month (January to December), genetic group of the cow, age at months of calving (33 to 190) and days in milk at each test-day. Random effects were sire, cow and residual with test-days treated as repeated records within each cow within each lactation. For the four genetic groups the milk yield (MY) means were 1/2H = 8.61 kg ± 1.16 kg, 1/4H = 5.34 kg ± 0.46 kg, 5/8H = 7.42 kg ± 0.39 kg and 5/8Hinter se = 5.76 kg ± 0.46 kg; the fat yield (FY) means were 1/2H = 0.375 kg ± 0.052 kg, 1/4H = 0.231 kg ± 0.026 kg, 5/8H = 0.299 kg ± 0.025 kg and 5/8Hinter se = 0.231 kg ± 0.026 kg; and the fat percentage (FP) means were 1/2H = 4.45 kg ± 0.29%, 1/4H = 4.08 kg ± 0.12%, 5/8H = 3.87 kg ± 0.10% and 5/8Hinter se = 3.89 kg ± 0.12%. Phenotypic correlations between tests were MY = 0.97, FY = 0.94 and FP = 0.98. The best productive performance was for the 1/2H group, followed by the 5/8H group. The performance of the synthetic group was substantially below the performance of the 5/8H group.

Curvas de lactação de vacas holandesas do Estado do Paraná, Brasil

A data set from the dairy herd analysis system in the State of Parana, Brazil (PARLPR - APCBRH), containing 27029 lactation records from 422 herds, was used to plot lactation curves. Lactation curves were plotted according to three parity groups and six levels of production. Production at peak increases with increases in herd production level and with increases in lactation number. Daily decline increases with increases in herd production level, in the case of second or greater lactation; for first lactation animals, no trend was identified for this characteristic. The curves, peak and persistency values obtained are to be used as management tools on dairy farms in the State of Parana.