Effect of ß-casein A1 or A2 milk on body composition, milk intake, and growth in Holstein, Simmental, and crossbred dairy calves of both sexes.

The aim of this study was to compare the effects of feeding homozygous ß-CN A1 or A2 milk on the body composition, milk intake, and growth of German Holstein (GH), German Simmental (GS), and crossbred (CR) dairy calves of both sexes during the first 2 wk of life. A total of 104 calves (n = 54 female, f; and n = 50 male, m) from the breed groups GH (n = 23), GS (n = 61), and crossbred GH × GS (n = 20) were evaluated. Calves were weighed after birth and received colostrum ad libitum. On the second day, calves were alternately housed in pairs in double-igloo systems according to their random birth order and received either A1 milk (n = 52; 27 female and 25 male) or A2 milk (n = 52; 27 female and 25 male). They were offered 7.5 L/d, and the individual actual total milk intake was recorded. Daily energy-corrected milk intake was also calculated based on the milk composition (fat and protein). Fecal scores were recorded daily. On d 15, visceral adipose tissue (VAT) volume was assessed by open magnetic resonance imaging and dual-energy X-ray absorptiometry (DXA). In addition, fat and lean mass (g), as well as bone mineral content (g) and bone mineral density (g/cm2), were determined by DXA. The body composition, milk intake, and growth were similar between the 2 types of milk in the first 2 wk of life. Female calves had more VAT and fat mass, but less lean mass than male calves. GH and CR calves had more VAT and less lean mass than GS calves. Male calves were heavier than female calves after birth and on d 15. The average days with diarrhea and diarrhea occurrence were similar between calves fed A1 and A2 milk and between both sex groups. GS calves presented slightly more days with diarrhea and increased odds of having diarrhea compared with GH calves, not differing from CR.

Perfil metabólico de vacas Holandês e mestiças Holandês x Jersey no periparto / Metabolic profile of Holstein and crossbred Holstein x Jersey cows in the peripartum

O objetivo do presente trabalho foi determinar e comparar o perfil metabólico de vacas Holandês (H) e mestiças Holandês x Jersey (HxJ) no periparto. Avaliaram-se 24 vacas, sendo 11 vacas Holandês e 13 mestiças Holandês x Jersey. Semanalmente, coletou-se sangue para a determinação das concentrações séricas de glicose, beta-hidroxibutirato (BHB), proteína total, albumina, aspartato aminotransferase (AST), creatinoquinase (CK), cálcio total, cálcio iônico, magnésio, fósforo inorgânico e colesterol. Avaliou-se também o peso vivo e o escore de condição corporal (ECC). Os dados foram submetidos à análise de variância com medidas repetidas no tempo. As vacas Holandês apresentaram maior peso vivo. Não houve diferença entre os grupamentos genéticos para ECC. Foi observada tendência de maiores concentrações séricas de BHB, AST e maior concentração de cálcio iônico em vacas mestiças Holandês x Jersey. Vacas mestiças Holandês x Jersey e Holandês apresentaram perfil energético similar durante o período de transição pré e pós-parto na maioria dos indicadores, com exceção do cálcio, que foi maior nas vacas mestiças, e do fósforo, que foi superior nas vacas Holandês.(AU)

The aim of this study was to determine and compare the metabolic profile of Holstein (H) and crossbred Holstein x Jersey (HxJ) on peripartum. For this, 24 cows were evaluated, 11 Holstein and 13 crossbreeds Holstein x Jersey. Weekly, venous blood sample were collected to determine concentration of glucose, beta-hydroxybutyrate (BHBA), total protein, albumin, aspartate aminotransferase (AST), creatine kinase (CK), total calcium, ionic calcium, magnesium, inorganic phosphorus and cholesterol. Body weight (BW) and body condition score (BCS) were also evaluated. The data were submitted to analysis of variance with repeated measures in time. Holstein cows presented higher BW, however, there was no difference for BCS in compare to crossbreed Holstein x Jersey cows. Tendency for higher serum concentrations of BHBA, AST and higher concentration of ionic calcium was observed in crossbreed cows in comparison to the Holstein. The energetic profile during the pre and postpartum transition period is similar for both genetic groups with higher concentrations of BHBA on the first week of lactation, however, with a tendency of higher serum concentrations of BHBA for crossbreed cows. Higher concentrations of ionic calcium were observed in crossbreed cows and higher concentrations of phosphorus in Holstein cows on peripartum. Holstein and Holtein x Jersey crossbreed cows have a similar energy profile during the pre and postpartum transition period in most of the indicators, except for calcium that was higher in crossbred cows and higher phosphorus in Holstein cows.(AU)

Produção e composição do leite em função da alimentação de vacas mestiças Holandês x Zebu confinadas em condições experimentais no Brasil: metanálise / Milk yield and composition a function of feeding of crossbred Holstein x Zebu cows confined under experimental conditions in Brazil: meta-analysis

Objetivou-se avaliar os fatores da composição da dieta que podem interferir no consumo, na digestibilidade, na produção e na composição do leite de vacas mestiças Holandês x Zebu confinadas em condições experimentais no Brasil. A metanálise foi utilizada para o levantamento de trabalhos científicos de domínio público, compreendendo o período de janeiro de 2000 a dezembro de 2015. A base de dados foi constituída por 40 experimentos com 159 tratamentos, envolvendo 735 vacas em lactação. O consumo de nutrientes digestíveis totais (NDT) é comprometido pelo teor de fibra em detergente ácido (FDA) da dieta, relacionando-se com a digestibilidade da matéria seca (MS) e da fibra em detergente neutro (FDN), o que repercute na eficiência alimentar (EA). Observa-se a relação do teor de carboidratos não fibrosos (CNF) da dieta com o teor de lactose e o efeito do teor de MS da dieta e o elevado teor de FDN no consumo em função das características específicas dos tipos de volumosos utilizados. O consumo de NDT da dieta é prejudicado pela digestibilidade da MS e, principalmente, da FDN em função da proporção e das características dos volumosos utilizados na dieta, e esses fatores repercutem na EA, bem como na produção e na composição do leite.(AU)

The aim was to evaluate diet composition factors that may interfere with intake, digestibility, milk yield and composition of crossbred Holstein x Zebus cows confined under Brazilian experimental conditions. The meta-analysis was used for the survey of scientific works of public domain, covering the period from January 2000 to December 2015. The database consisted of 40 experiments with 159 treatments, involving 735 lactating cows. The voluntary intake of total digestible nutrients (TDN) is compromised by the acid detergent fiber (FAD) content of the diet, related to dry matter digestibility (DM) and neutral detergent fiber (NDF), affecting dietary efficiency (DE). The relation of the non-fibrous carbohydrate (NFC) content of the diet with the lactose content and the effect of the DM diet content and the high NDF content on the voluntary intake are specific characteristics of the types of roughage used. Dietary NDT intake is affected by the digestibility of DM and, mainly, NDF, depending on the proportion and characteristics of the nutrients used in the diet, and these factors have an impact on dietary efficiency, as well as on milk composition.(AU)

Influência da sanificação da água e das práticas de ordenha na qualidade do leite / Influence of water treatment and milking practices on milk quality

Objetivou-se avaliar a influência da cloração da água utilizada em salas de ordenha, assim como do manejo e da infraestrutura da ordenha, sobre a qualidade microbiológica da água e do leite. Foi instalado um equipamento para cloração de água, por duas semanas, na caixa de água de 20 propriedades leiteiras. Foram coletadas amostras de água e leite ao primeiro dia (sem cloro: controle), no sétimo e 14° dias (com cloro) e no 21º dia após a desinstalação dos cloradores (sem cloro: controle). Foram realizadas análises microbiológicas da água e do leite (contagem de células somáticas do leite, bactérias psicotróficas, mesófilas e coliformes totais), análises físico-químicas da água (pH, dureza e matéria orgânica), e aplicou-se um questionário estruturado aos produtores visando conhecer as técnicas de manejo de ordenha adotadas na propriedade. O uso de cloração na água melhorou (P<0,0001) a qualidade microbiológica da água, porém não afetou a qualidade microbiológica do leite (P>0,05). Práticas adequadas de manejo e higiene de ordenha e adequada estrutura para a ordenha estão relacionadas a baixas contagens de microrganismos no leite. Conclui-se que a cloração melhora a qualidade microbiológica da água, sem afetar a qualidade microbiológica do leite, a qual é melhorada pela adoção de boas práticas de ordenha e adequada infraestrutura.(AU)

The aim was to evaluate the influence of the use of sanitizing the water used on dairy farms, the management and the infrastructure on the dairy farm on the microbiological quality of water and milk. It was installed an equipment to chlorinate the water for a period of two weeks, in the water box of 20 dairy farms. In each dairy farm, water and milk samples were collected, being the first day (without chlorine: control), in the 7th and 14th day (chlorine), and 21 days after uninstalling the chlorinators (Chlorine-free: control). Microbiological analysis of water and milk (Somatic cell counts of milk, psychrotrophic bacteria, mesophilic and total coliforms) and physicochemical analysis of water were performed and a survey was applied to the farmers. The use of chlorine tablets in water improved (P<0.0001) the microbiological quality of water, but did not affect the microbiological quality of the milk (P>0.05). Management practices, hygiene and the structure of dairy farms are related to low microorganism counts in milk. In conclusion, chlorination of water improves the microbiological quality of water without affecting the microbiological quality of milk, which is improved by the adoption of good milking practices and adequate infrastructure.(AU)