Influence of oestrus on the heat stability and other characteristics of milk from dairy goats

We examined the heat stability, somatic cell count (SCC), pH, fat, protein and lactose content of milk from goats during the oestrous period, in order to investigate evidence of possible oestrus effects on milk physical and chemical properties. Goats free from mammary infections were ranked on average SCC from three tests so that they could be stratified randomly in pairs to synchronized oestrus or left as unsynchronized non-oestrus controls. The synchronisation consisted of insertion of an intravaginal progesterone-releasing device for 17 cl, and introduction of the bucks the day of the device removal (DO). The repeated measurements analysis of variance model included the fixed effects of the experimental group (oestrus or control) and day and the corresponding interaction and also the random effect of doe. Reduced milk-heat stability, increased SCC, increased protein content and reduced pH were found in the milk samples of the oestrus group on D1, 2 and 3. The fat and lactose content of the milk was not affected by oestrus. These data indicate that the milk of goats during the mating period has reduced heat stability and, therefore, that dilution into bulk tanks should be recommended to avoid clotting when milk is intended for high thermal treatment

A Tool For Explaining The Differences on Renneting Characteristics of Milks From Different Origins: The Surface Hydrophobicity Approach

The differences between renneting characteristics of raw milk samples from different origins (bovine, ovine, caprine, buffalo) were investigated by protein surface hydrophobicity approach. 8-Anilinonaphthalene-1-sulfonic acid (ANS) binding method was used to evaluate surface hydrophobicity of raw milk samples and rennet precipitates. The following surface hydrophobicity parameters were calculated: number of surface hydrophobic sites (F (max)), dissociation constant of the fluorescent ANS-protein complex (K (d)), binding affinity of ANS to protein surface (1/K (d)), the average tightness of binding of ANS to the protein (F (max)/K (d)), turnover number (k (cat)), and protein surface hydrophobicity index (PSHI). The number of hydrophobic sites on the protein surface was found to be highest in cow milk, whereas ovine milk samples had the lowest number of hydrophobic sites and binding affinity to ANS. Protein content was not found directly related to the number of surface hydrophobic sites. The binding affinity of the proteins to ANS was greater in buffalo milk. PSHI was found to be the highest for bovine milk and the lowest for ovine milk. Renneting period was interpreted in two phases (enzymatic phase and flocculation phase) for each origin via ANS partition curves of rennet precipitates. Same trends between bovine-ovine and caprine-buffalo milks were observed during renneting. Buffalo milk completed both of two phases and total renneting period significantly earlier than the milks from the other origins. The hydrophobic parameters of proteins were found to play a key role on coagulation properties.Wo

Consumo de volumosos, produção e composição físico-química do leite de cabras F1 Boer × Saanen Roughage intake, milk yield and physicochemical composition from F1 Boer × Saanen goats

Avaliaram-se os efeitos do fornecimento de volumosos suplementares sobre o consumo, a produção e a composição físico-química do leite de cabras F1 (Boer &#215;Saanen). Utilizaram-se 18 cabras distribuídas em três baias, recebendo como suplemento, à vontade, silagem de sorgo, silagem de milho ou feno de amoreira com controle diário do consumo de matéria seca. A média diária para produção semanal foi calculada reunindo-se dados leiteiros em três períodos pós-parto: 1 (34 a 40 dias/7 dias); 2 [(64 a 70 dias/7 dias) + (91 a 97 dias)/7 dias)]/2; e 3 (125 a 131 dias/7 dias) e a média pontual diária do período pelas datas de referência dos períodos da média diária para produção semanal, que foi correlacionada à composição de gordura, proteína, lactose e extrato seco total e à contagem de células somáticas. Os dados semanais de acidez e densidade foram agrupados em 37, 81&plusmn;13, 128 e 151&plusmn;10 dias pós-parto. Com modelos mistos, o animal foi computado como aleatório e os efeitos fixos foram três suplementos e três períodos (composição, médias diárias as produções semanal e do período) ou quatro (acidez e densidade). O consumo de feno de amoreira (0,657 kg) superou o de silagem de milho (0,604 kg), que foi superior ao de silagem de sorgo (0,305 kg). No período 2, a composição em extrato etéreo foi menor, em razão do decréscimo de gordura e lactose. No período 3, a composição em proteína e a acidez aumentaram e a densidade foi maior nos períodos 1 (1,0270) e 3 (1,0277). A mamite aumentou a CCS no período 2. Para proteína, o tipo de suplemento não foi significativo, mas houve efeito da interação período pós-parto &#215;suplemento. As demais variáveis não foram influenciadas pelo tipo de suplemento, apenas pelo período pós-parto. O feno de amoreira aumenta o consumo suplementar pelas cabras em relação às silagens de milho e sorgo, mas não melhora as médias de produção e composição do leite. Cabras Boer &#215;Saanen em pastejo e sob suplementação têm bom potencial leiteiro.<br>The effects were assessed of supplying supplementary roughage on intake, milk yield and milk physical and chemical composition in F1 (Boer &#215;Saanen) goats. Eighteen females were placed in three stalls, and received as ad libitum supplement sorghum silage, corn silage and mulberry hay (MHT), with daily control of dry matter intake. The average daily production per week was calculated by gathering the milk data in three post-parturition periods: 1 (34-40 days/7 days); 2 [(64-70 days/7 days) + (91-97 days)/7 days)]/2 and 3 (125-131 days/7 days). Daily spot-average of each period (DSAP) was calculated from the reference dates of average daily production per week, that was correlated with the composition of fat, protein, lactose, total solids composition and the somatic cell count. The weekly data for acidity and density were grouped in 37, 81&plusmn;13, 128 and 151&plusmn;10 days post-parturition. Using mixed models, the animal was computed as random and the fixed effects were three supplements and three periods (composition, average daily production per week and per period) or four (acidity and density). Mulberry hay intake (0.657 kg) was greater than corn silage (0.604 kg) that was greater than sorghum silage (0.305 kg). In period 2, the ether extract composition was smaller because of the decrease in fat and lactose. In period 3, protein and acidity increased and density was great in periods 1 (1.0270) and 3 (1.0277). Mastitis increased SCC in period 2. The type of supplement was not significant for protein, but there was post partum period &#215;supplement effect. The other variables were not influenced by the type of supplement, only by the post-partum period. Mulberry hay increased the supplement intake by the goats compared to corn and sorghum silage, but it did not improve milk yield = means and composition. Grazing Boer &#215;Saanen goats with supplementation have good milk production potential