Variation of nutritive value, measured by proximal hyperspectral sensing, of herbage offered to grazing dairy cows

A trial was carried out at Dexcel in Hamilton to investigate the effects of silage supplementation of grazing dairy cows post-peak lactation. Forage mixtures used in the four week trial were based on previous trial results and information from in vitro and in sacco incubations. Sulla and maize silages were used to supplement pasture and to meet minimum requirements for protein. Five groups of ten cows were grazed on a restricted daily allowance of 18 kg dry matter (DM) pasture/cow to simulate a summer pasture deficit, and four groups received sulla silage (S) or maize silage (M) alone or in mixtures of 25M:15S or 15M:25S to make up 40% of total DM intake. A sixth group was given an unrestricted (38 kg DM/cow/day) pasture allowance. The pasture was of high nutritive value and not typical of usual summer conditions, which limited the effects of supplementation in the trial. The restricted pasture allowance resulted in a low level of substitution (0.29) when the silages were fed and substantially increased feed intakes. Although differences in cow responses to the silage mixtures were minor, liveweight and milk production were improved relative to restricted pasture allowance but not for cows given 38 kg pasture DM/ day. The low level of substitution demonstrated the impact of the restricted pasture allowance on cow performance. In sacco data show highest DM degradation rate (k, h-1) when cows were fed pasture with sulla silage (0.08); diets with a high proportion of maize silage were degraded slowly (P

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Identification of Genomic Regions Associated with Concentrations of Milk Fat, Protein, Urea and Efficiency of Crude Protein Utilization in Grazing Dairy Cows

Genes ◽

10.3390/genes12030456 ◽

2021 ◽

Vol 12 (3) ◽

pp. 456

Author(s):

Hewa Bahithige Pavithra Chathurangi Ariyarathne ◽

Martin Correa-Luna ◽

Hugh Thomas Blair ◽

Dorian John Garrick ◽

Nicolas Lopez-Villalobos

Keyword(s):

Gene Ontology ◽

New Zealand ◽

Dairy Cows ◽

Candidate Genes ◽

Milk Fat ◽

Crude Protein ◽

Single Locus ◽

Protein Utilization ◽

Grazing Dairy Cows ◽

Genomic Regions

The objective of this study was to identify genomic regions associated with milk fat percentage (FP), crude protein percentage (CPP), urea concentration (MU) and efficiency of crude protein utilization (ECPU: ratio between crude protein yield in milk and dietary crude protein intake) using grazing, mixed-breed, dairy cows in New Zealand. Phenotypes from 634 Holstein Friesian, Jersey or crossbred cows were obtained from two herds at Massey University. A subset of 490 of these cows was genotyped using Bovine Illumina 50K SNP-chips. Two genome-wise association approaches were used, a single-locus model fitted to data from 490 cows and a single-step Bayes C model fitted to data from all 634 cows. The single-locus analysis was performed with the Efficient Mixed-Model Association eXpedited model as implemented in the SVS package. Single nucleotide polymorphisms (SNPs) with genome-wide association p-values ≤ 1.11 × 10−6 were considered as putative quantitative trait loci (QTL). The Bayes C analysis was performed with the JWAS package and 1-Mb genomic windows containing SNPs that explained > 0.37% of the genetic variance were considered as putative QTL. Candidate genes within 100 kb from the identified SNPs in single-locus GWAS or the 1-Mb windows were identified using gene ontology, as implemented in the Ensembl Genome Browser. The genes detected in association with FP (MGST1, DGAT1, CEBPD, SLC52A2, GPAT4, and ACOX3) and CPP (DGAT1, CSN1S1, GOSR2, HERC6, and IGF1R) were identified as candidates. Gene ontology revealed six novel candidate genes (GMDS, E2F7, SIAH1, SLC24A4, LGMN, and ASS1) significantly associated with MU whose functions were in protein catabolism, urea cycle, ion transportation and N excretion. One novel candidate gene was identified in association with ECPU (MAP3K1) that is involved in post-transcriptional modification of proteins. The findings should be validated using a larger population of New Zealand grazing dairy cows.

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Supplementation of grazing dairy cows with a brewers grains/treated straw mixture

Proceedings of the British Society of Animal Production (1972) ◽

10.1017/s0308229600018274 ◽

1990 ◽

Vol 1990 ◽

pp. 46-46 ◽

Cited By ~ 1

Author(s):

J.D. Leaver ◽

R.C. Campling

Keyword(s):

Dairy Cows ◽

Crude Protein ◽

Dry Matter ◽

Barley Straw ◽

Severe Drought ◽

Grass Silage ◽

Metabolisable Energy ◽

Grazing Dairy Cows ◽

Similar Cost ◽

Friesian Cows

Supplementary feeding of grazing dairy cows is often uneconomic, and whilst supplementation with silage (buffer feeding) can be worthwhile, this often leads to a depletion of winter forage stores. In this study, a mixture of brewers grains and treated straw was used as a supplement. Offered as a 1:1 mixture in the dry matter (DM), it is a purchased substitute for grass silage, having a similar cost, and similar metabolisable energy (ME) and crude protein (CP) contents. The high seasonality adjustments to milk price in mid-late season make supplementation potentially worthwhile.Experiments were carried out from April to September in 1988 and 1989, which had moderate and very low rainfall respectively. Each year 20 British Friesian cows which calved December to March (1988 experiment) and February-April (1989) were allocated at random to either treatment B or C. In B, the cows were offered a 1:1 mixture (DM basis) of brewers grains and NaOH treated chopped barley straw for 60 minutes after morning milking. In C, the cows received no supplement. Both groups were fed 1.0 kg/day of concentrates in the milking parlour. Due to the severe drought in 1989, concentrate feeding was increased to 5.0 kg/day for all cows during the last 4 weeks of the experiment. Also, urea-treated whole crop wheat was fed at a level of 2.5 kg DM/day during the last 7 days.

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