The effects of sprinkler+fan, fish meal or dietary fat on milk yield and milk composition of dairy cows in mid lactation during summer

Abstract

Two studies were conducted to evaluate 1. the effectiveness of sprinkler+fan (SF) and fish meal (FM) and 2. SF and protected fat (PF) in alleviation of heat stress in dairy cows in mid lactation. The studies were carried out in 2 × 2 factorial arrangement, in a 4 × 4 Latin square design on four multiparous lactating dairy cows. The treatments in the first trial were 1. no SF and no FM, 2. no SF and 3.67% FM in the diet (on DM basis), 3. SF and no FM and 4. SF and 3.67% FM. The treatments in the second trial were 1. no SF and no PF, 2. no SF and 2.54% PF in the diet (on DM basis), 3. SF and no PF and 4. SF and 2.54% PF. Cows were fed with isoenergetic and isonitrogenic TMR, containing 2.52 Mcal ME/kg DM and 180 g CP/kg DM. The cows received mild heat stress for 9 h (from 07.00 to 10.00 and from 17.00 to 23.00) and moderate heat stress for 7 h (from 10.00 to 17.00) daily for the entire experimental period.SF ). FM had no effect on milk yield of neither cooled nor no cooled cows, but tended to increase (P=0.12) milk protein, independently from SF application. Additionally, PF increased FCM and fat yield (P<0.05) and tended to increase (P=0.07) milk fat content independently from SF application.Journal of Animal and Feed Sciences, 14, 2005, 639- FATS AFFECT MILK YIELD AND COMPOSITIONThe results of both studies suggest that applying sprinklers plus fan can improve milk yield better than nutritional manipulation using either FM or PF. The results also suggested that PF could be more beneficial than FM under heat stress condition when the dietary protein level is high.

Heat production, eating behavior and milk yield of lactating cows fed two rations differing in roughage content and digestibility under heat load conditions

“…These data are in accord with results from earlier studies that used soy hulls as corn silage replacer in TMR for lactating cows (Halachmi et al, 2004;Miron et al, 2003). However, other studies that employed starchy grain (Cummins, 1992;West et al, 1999) or fat supplementation (Chan et al, 1997;Huber et al, 1994;Serbester et al, 2005) used to increase the energy content of TMR, failed to enrich DMI, milk and milk protein production up to the levels obtained in the present study.…”

“…They suggested to reduce it to 12-15% of total mixed rations (TMRs) fed to high producing lactating cows that are exposed to hot weather conditions. Partial replacement of forage by starchy grain (Cummins, 1992;West et al, 1999) and addition of fat or protected fat to the diet (Chan et al, 1997;Huber et al, 1994;Serbester et al, 2005) have been tried as approaches to increase the energy consumption of cows under heat load conditions. These strategies have proven ineffective at increasing DMI, milk and milk fat production.…”

Efeitos da substituição parcial do farelo de soja por uma fonte de proteína microbiana derivada de levedura, em dietas de vacas holandesas em lactação

“…Moussavi et al (2007) verificaram que a utilização de uma fonte de proteína não degradável no rúmen ou ácidos graxos n-3-polinsaturados para vacas no inicio da lactação, aumentou a ingestão de matéria seca e a produção de leite, sem nenhuma alteração na composição do leite. Entretanto, Serbester et al (2005) não observaram efeitos do uso de proteína não degradável no rúmen sobre a produção de leite em vacas, mas verificaram aumento absoluto no teor de proteína do leite.…”