Crude glycerin in supplement to primiparous lactating cows grazing on tropical pasture: nutritional and productive characteristics

Abstract

-The objective of this study was to evaluate the nutritional and productive characteristics of primiparous lactating cows grazing on tropical pasture, using different levels of crude glycerin in the supplement. The experiment was conducted at Rancho Santana farm, located in Jequié city, Bahia, Brazil, in the period from December 21, 2010 to March 16, 2011. Ten ¾ Holstein × ¼ Dairy Gyr lactating primiparous cows, with 109±24 days of lactation and a mean age of 30±6 months and mean body weight of 426.2±68.29 kg were distributed into five treatments, using two simultaneous 5 × 5 latin squares. Treatments consisted of inclusion levels (0, 94, 191, 289, 389 g/kg dry matter basis) of crude glycerin in the supplement. Intake, digestibility, milk production and composition were measured. Results were statistically analyzed by analysis of variance and regression at 0.05 probability. For all consumption variables no significant differences were found between the levels of crude glycerin. Except for the digestibility of ether extract, all digestibility values were similar between treatments. The fat content and yield showed quadratic effect between treatments. No significant differences were observed for protein, lactose, total solids, nonfat dry extract, fat:protein ratio, milk urea nitrogen and somatic cell count between treatments. For primiparous lactating cows grazing on tropical pasture, up to 389 g of crude glycerin/kg of dietary supplement can be included without nutritional and productive interference.

Effects of high concentrations of dietary crude glycerin on dairy cow productivity and milk quality

“…Previous studies using lower glycerin concentrations also showed a reduction in milk fat (Khalili et al, 1997;Chung et al, 2007;Santana Junior et al, 2013). The increases in ruminal propionate:acetate ratio previously reported for animals on glycerol diets (Carvalho et al, 2011) may explain these changes, because acetate represents the main precursor to milk fat.…”

“…The improvement in feed efficiency in 21-d periods may be maintained by NEFA and will likely not be continued in a longer feeding period because of lower DMI in animals fed especially G30. Santana Junior et al (2013), evaluating changes in body condition and DMI, hypothesized that feed efficiency decreases with increasing dietary glycerin. This apparent discrepancy may result from the different indicators evaluated in the 2 studies: in the current study changes in milk yield were observed but not in BCS (average 3.13, in a 1-to-5 scale).…”

Glicerina bruta na dieta de novilhas Nelore em pastejo no período seco

“…Resultados semelhantes foram encontrados por Santana Junior et al (2013) que trabalhando com suplementação de vacas leiteiras em sistema de pastejo de Brachiaria brizantha com adição de GB na dieta (0,00; 3,33; 6,71; 10,05 e 12,74% na MS), observaram efeito linear crescente na digestibilidade do EE de 2,88% para cada um% de GB adicionado a dieta.…”

Glicerina bruta na dieta de vacas lactantes mantidas em pastagem tropical: comportamento ingestivo

“…Vários estudos descreveram a utilização de variáveis comportamentais para nortear a avaliação de dietas (ALLDEN; WHITTAKER, 1970;MISSIO et al, 2010;PEREIRA et al, 2011;SANTANA JÚNIOR et al, 2013b;SANTANA JÚNIOR et al, 2013c). Paralelamente, a ingestão de matéria seca pelas vacas mantidas em pastagens tropicais se constitui em um dos principais fatores que limitam a produção de leite (FUKUMOTO et al, 2010).…”

“…Neste contexto, a inclusão da glicerina bruta na dieta pode modificar o comportamento ingestivo dos ruminantes, notadamente em razão de algumas das suas características físicas e químicas. A sua apresentação na forma líquida à temperatura ambiente, como também o seu caráter lipídico, se constituem em exemplos destas características (SANTANA JÚNIOR et al, 2013a).…”