Gastrointestinal tract size, total-tract digestibility, and rumen microflora in different dairy cow genotypes

Abstract

Interpretive Summary 67 DAIRY COW DIGESTIBILITY 68 3Beecher 69 70This study aimed to measure if differences existed among dairy cow genotypes in 71 gastrointestinal tract size, digestibility and selected rumen microbial populations. Jersey and 72JerseyHolstein-Friesian cows had proportionally larger gastrointestinal tract weight than 73Holstein-Friesian cows. Jersey cows had a superior total tract digestibility and lower relative 74 abundance of Ruminococcus flavefaciens in the rumen than Holstein-Friesian cows. These 75 differences could contribute to the production efficiency differences among genotypes 76 previously reported. 77The superior milk production efficiency of Jersey (JE) and JerseyHolstein-Friesian 80 (JEHF) cows compared with Holstein-Friesian (HF) has been widely published. The 81 biological differences among dairy cow genotypes, which could contribute to the milk 82 production efficiency differences, have not however been as widely studied. A series of 83 component studies were conducted using cows sourced from a longer-term genotype 84 comparison study (JE, JEHF and HF). The objectives were to: (i) determine if differences 85 exist among genotypes regarding gastrointestinal tract (GIT) weight, (ii) assess and quantify 86 if the genotypes tested differ in their ability to digest perennial ryegrass, and (iii) examine the 87 relative abundance of specific rumen microbial populations potentially relating to feed 88 digestibility. Over 3 yr the GIT weight was obtained from 33 HF, 35 JE and 27 JEHF non-89 lactating cows post-slaughter. During the dry period the cows were offered a perennial 90 ryegrass silage diet at maintenance level. The unadjusted GIT weight was heavier for the HF 91 than for the JE and JEHF. When expressed as a proportion of bodyweight (BW) the JE and 92 JEHF had a heavier GIT weight than the HF. In vivo digestibility was evaluated on 16 each 93 of JE, JEHF and HF lactating dairy cows. Cows were individually stalled allowing for the 94 total collection of feces and were offered freshly cut grass twice daily. During this time daily 95 milk yield, BW and dry matter intake (DMI) were greater for HF and JEHF than for JE. 96Milk fat and protein concentration ranked oppositely. Daily milk solids yield did not differ 97 among the 3 genotypes. Intake capacity, expressed as DMI/BW, tended to be different among 98 treatments, with the JE having the greatest DMI/BW, the HF the lowest and the JEHF cows 99 were intermediate. Production efficiency, expressed as milk solids/DMI, was higher for the JE 100 than HF and JEHF. Digestive efficiency, expressed as digestibility of dry matter, organic 101 matter, N, neutral detergent fibre and acid detergent fibre, was higher for JE than HF. In 102 grazing cows (n=15 per genotype) samples of rumen fluid, collected using a transesophageal 103 5 sampling device, were analyzed to determine the relative abundance of rumen microbial 104 populations of cellulolytic bacteria, protozoa and fungi. These are critically important for 105 fermentation of...

Dairy cow breed interacts with stocking rate in temperate pasture-based dairy production systems

“…For example, Prendiville et al (2009) reported that Jersey (J) cows required 7 to 8% less total feed for every kilogram of milk fat and protein produced in a pasture-based dairy production system compared with HF cows. This is consistent with the reported differences in the mass of the gastrointestinal tract (i.e., 24% lighter in J cows; Beecher et al, 2014), a 2 to 3% greater digestibility of DM and NDF by J cows (Beecher et al, 2014), and the greater use of consumed ME for productive purposes by the J cow (L'Huillier et al, 1988) compared with HF cows. The improvement in the efficiency of ME use, however, was apparent only in a grazing environment with restricted DMI, where J cows produced 20% more milk/kg of DMI (L'Huillier et al, 1988); under ad libitum feeding, this ME conversion gain disappeared.…”

Harnessing the genetics of the modern dairy cow to continue improvements in feed efficiency

“…A study with dairy cattle failed to find a difference in microbial populations of high and low RFI cows (Rius et al, 2012). However, the relative abundance of Ruminococcus flavefaciens was correlated with digestibility and was considered a possible explanation for differences in efficiency of grazing Irish Jersey compared with Holstein cows (Beecher et al, 2014). In the end, it is difficult to know what is causal in the relationship between the microbiome and digestibility.…”

Effects of concentrate crude protein content on nutrient digestibility, energy utilization, and methane emissions in lactating dairy cows fed fresh-cut perennial grass

“…It is well documented that improving productivity can lead to a reduction in CH 4 emissions per unit of produce (Chagunda et al, 2009;Wall et al, 2010;Cottle et al, 2011) while making mitigation strategies appealing to producers. Beecher et al (2014) and Palladino et al (2010) showed that Holstein-Friesian cows on perennial ryegrass silage diets offered at maintenance levels and grazing perennial ryegrass, respectively, may exhibit differences in production efficiency compared with Jersey and Jersey × Holstein-Friesian cows. However, comparisons of CH 4 emissions between Holstein and other breeds under grazing or zero-grazing conditions have been limited, with the literature focusing on ensiled forage (Xue et al, 2011;Arndt et al, 2015).…”