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Lactation and body composition responses to fat and protein supplies during the dry period in under - conditioned dairy cows

Por: Jaurena, Gustavo. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Nutrición y Alimentación Animal. Buenos Aires, Argentina.
Colaborador(es): Moorby, J. M. Aberystwyth University. Institute of Biology, Environment and Rural Sciences (IBERS), Gogerddan, Aberystwyth, United Kingdom.
ISSN: 0022-0302.Tipo de material: Artículos y capítulos. Recurso electrónico.Tema(s): DRY COW | MILK PRODUCTION | MILK QUALITY | BODY COMPOSITION | Recursos en línea: Haga clic para acceso en línea | LINK AL EDITOR En: Journal of dairy science Vol.100, no.2 (2017), p.1107-1121, grafs., tbls.Resumen: An experiment was designed to study the effect of precalving supplementation with protein (Pr) and rumeninert fat (F) on body composition and subsequent milk production and composition. Forty Holstein-Friesian dairy cows were allocated to 1 of 4 dietary treatments in the dry period (DP) based on a first - cut ryegrass silage, with 6 mature (in their third or greater pregnancy) and 4 young (in their second pregnancy) cows per treatment. These were low Pr, low F (silage alone); low Pr, high F (silage with 10% rumen-inert fat, mixed on a dry matter basis); high Pr, low F [silage with 5% high-protein corn gluten meal (CGM)]; and high Pr, high F (silage with 5% CGM and 10% rumen-inert fat). All the diets were individually offered ad libitum and dry matter intake (DMI) was recorded daily during the DP. After calving, all cows received ryegrass silage plus 8 kg/d of a commercial dairy concentrate. During the DP, DMI was higher for mature than for young cows. All animals recovered body condition score (0.13 units/wk, 1–5 scale), reaching a maximum score of 2.4 some days before calving. Precalving maximum muscle longissimus dorsi (LD) depth was greater for mature (47.5 mm) than for young cows 45.7 mm), and milk fat concentration was also higher for mature than foryoung cows (40.2 and 39.0 g/kg, respectively). Supplementation with CGM increased maximum LD depth (from 45.9 to 47.6 mm), calf birth weight (low Pr = 43.2, high Pr = 46.3 kg), and milk crude protein concentration (from 30.8 to 31.6 g/kg). Fat supplementation in the DP of the mature cows increased maximum back fat depth (from 3.6 to 4.5 mm), milk yield (low F = 26.3, high F = 28.7 kg/d), and Pr yields (low F = 837, high F = 899 g/d). Inclusion of F in the DP diets reduced casein concentration in milk at wk 3 of lactationlactation from 26.3 to 24.5 g/kg. Milk CP yield was also increased by CGM supplementation when compared within cows receiving F-supplemented silages (low Pr, high F = 832 g/d; high Pr, high F= 877 g/d). It can be concluded that CGM supplementation in the DP increased subsequent milk Pr concentration, but milk Pr yield increased only in those animals also receiving F supplementation. Dry period diet supplementation with F increased maximum back fat depth and milk and CP yields in the mature cows, and led to more LD muscle mobilization during early lactation. Second calving cows had a lower DMI and milk fat concentration than mature cows.
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An experiment was designed to study the effect of precalving supplementation with protein (Pr) and rumeninert fat (F) on body composition and subsequent milk production and composition. Forty Holstein-Friesian dairy cows were allocated to 1 of 4 dietary treatments in the dry period (DP) based on a first - cut ryegrass silage, with 6 mature (in their third or greater pregnancy) and 4 young (in their second pregnancy) cows per treatment.
These were low Pr, low F (silage alone); low Pr, high F (silage with 10% rumen-inert fat, mixed on a dry matter basis); high Pr, low F [silage with 5% high-protein corn gluten meal (CGM)]; and high Pr, high F (silage with 5% CGM and 10% rumen-inert fat). All the diets were individually offered ad libitum and dry matter intake (DMI) was recorded daily during the DP. After calving, all cows received ryegrass silage plus 8 kg/d of a commercial dairy concentrate. During the DP, DMI was higher for mature than for young cows.
All animals recovered body condition score (0.13 units/wk, 1–5 scale), reaching a maximum score of 2.4 some days before calving. Precalving maximum muscle longissimus dorsi (LD) depth was greater for mature (47.5 mm) than for young cows 45.7 mm), and milk fat concentration was also higher for mature than foryoung cows (40.2 and 39.0 g/kg, respectively). Supplementation with CGM increased maximum LD depth (from 45.9 to 47.6 mm), calf birth weight (low Pr = 43.2, high Pr = 46.3 kg), and milk crude protein concentration (from 30.8 to 31.6 g/kg).
Fat supplementation in the DP of the mature cows increased maximum back fat depth (from 3.6 to 4.5 mm), milk yield (low F
= 26.3, high F = 28.7 kg/d), and Pr yields (low F = 837, high F = 899 g/d).
Inclusion of F in the DP diets reduced casein concentration in milk at wk 3 of lactationlactation from 26.3 to 24.5 g/kg. Milk CP yield was also increased by CGM supplementation when compared within cows receiving F-supplemented silages (low Pr,
high F = 832 g/d; high Pr, high F= 877 g/d). It can be concluded that CGM supplementation in the DP increased subsequent milk Pr concentration, but milk Pr yield increased only in those animals also receiving F supplementation.
Dry period diet supplementation with F increased maximum back fat depth and milk and CP yields in the mature cows, and led to more LD muscle mobilization during early lactation. Second calving cows had a lower DMI and milk fat concentration
than mature cows.

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