JDS communications最新文献

Increased expression of interferon-stimulated gene 15 (ISG15) in cervical cells on day 14 of pregnancy in Holstein heifers.

JDS communications

Pub Date : 2024-11-28 eCollection Date: 2025-01-01 DOI: 10.3168/jdsc.2024-0596

Graciana R Mendina, Victoria de Brun, Maria de Lourdes Adrien, Victoria Pons, Rodrigo Vivian Paradizo, Jorge Gil, Cecilia C Rocha, Mario Binelli, Ana Meikle

In cattle, expression of IFN-stimulated genes in the female reproductive tract has been reported as an early pregnancy diagnostic tool, as early as d 17 of pregnancy. The hypothesis of this study was that expression of ISG15 in the cervix of pregnant heifers is increased on d 14 of pregnancy. The objective was to compare the expression of ISG15 in cervical cells between pregnant and cyclic heifers (control, sham-inseminated) on d 14, 16, and 18 after insemination (d 0). Holstein heifers were submitted to an estrus synchronization protocol and inseminated with extender only ("control," n = 6), or with regular semen (n = 15). Heifers were classified as pregnant (n = 10) by ultrasound at d 30 through the detection of a viable embryo with a heartbeat. Blood samples from the coccygeal vein were collected to determine serum progesterone concentrations on d 14, 16, and 18. The expression of ISG15 and PGR in cervical cells collected through cytobrush was measured on d 14, 16, and 18. A receiver operating characteristic (ROC) curve was calculated to quantify the pregnancy diagnostic accuracy of ISG15 and PGR expression. The expression levels of ISG15 in cervical cells were significantly greater in pregnant compared with control heifers on d 14, and remained greater on d 16 and 18, whereas differences in PGR were observed only on d 18. Scatter plots and ROC analyses showed the most accurate prediction of pregnancy for ISG15 on d 16. In conclusion, cervical cells express greater ISG15 mRNA in pregnant versus control heifers as early as d 14 postinsemination, with the best accuracy on d 16.

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引用次数: 0

Automating hock wound detection in dairy cattle.

JDS communications

Pub Date : 2024-11-05 eCollection Date: 2025-01-01 DOI: 10.3168/jdsc.2024-0671

W Flanders, P S Basran, M Wieland

Hock scoring in dairy cattle is a crucial welfare assessment tool used to evaluate the condition of a cow's hocks, particularly for signs of injury, swelling, or lesions. These scores provide insight into the overall well-being of the animals and are essential for ensuring proper management and housing conditions. Accurate hock scoring is vital because it can indicate issues such as poor bedding quality or inadequate space, which directly affect the health and productivity of the herd. Traditionally, hock scoring is performed manually by trained observers. However, consistency in scoring can be a challenge. Two studies were conducted to quantify inconsistency in hock scoring. In one study, manual scoring reproducibility was measured. In the second study, manual and video scoring repeatability was measured. Repeatability was quantified with a weighted Cohen's kappa metric. Manual scoring was found to be inconsistent but more consistent than video scoring. This variability highlights the need for a more reliable, objective method of scoring. To address this, we explored the automation of hock score detection using artificial intelligence. Specifically, we employed a simple U-net semantic segmentation algorithm to detect wounds on the hocks without classifying them into specific categories. Automating the detection process can reduce observer bias, improve consistency, and allow for continuous monitoring of large herds. This approach holds promise for enhancing animal welfare by providing a more efficient and accurate method of assessing hock health in dairy cattle.

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引用次数: 0

Specificity of 2 peripartum blood markers for early-lactation acute uterine inflammation in pasture-fed, seasonal-calving dairy cows 两种围产期血液标记物对牧草喂养、季节性产犊奶牛泌乳早期急性子宫炎症的特异性。

JDS communications

Pub Date : 2024-11-01 DOI: 10.3168/jdsc.2023-0509

O.K. Spaans , J.R. Roche , C.R. Burke , C.V.C. Phyn , S. McDougall , C.B. Reed , B. Kuhn-Sherlock , A. Hickey , A. Heiser , M.A. Crookenden

A delayed recovery of the reproductive tract from natural inflammatory processes associated with postpartum involution will compromise further reproductive function. Following a literature review, we selected serum amyloid A (SAA) and α1-acid glycoprotein (α1-AGP) to assess as potential circulating markers of acute uterine inflammation, as concentrations of these 2 acute phase proteins were reported to be elevated early postpartum in dairy cows with active uterine infection. Convenience serum samples from an induced model of uterine infection were used to measure concentrations of these markers. Infection was induced by infusing either 10⁷ or 10⁹ cfu of Trueperella pyogenes (n = 9 cows each; bacteria group n = 18) or saline as a control (n = 18) into the uterus at 48 d postpartum. Although infection stimulated an increase in uterine polymorphonuclear neutrophils, SAA and α1-AGP concentrations in serum were not different between infusion groups. Cows were subsequently classified into uterine health groups based on the presence of endometritis, with or without the presence of T. pyogenes in uterine culture in response to uterine infusion. Mean SAA concentrations were greater in cows that were either endometritis negative–infection positive (n = 9), endometritis positive–infection negative (n = 5), or endometritis positive–infection positive, compared with the endometritis negative–infection negative (n = 11) cows. There was no difference between uterine health groups for α1-AGP concentrations.

生殖道从与产后内陷相关的自然炎症过程中恢复的延迟将损害进一步的生殖功能。根据文献综述，我们选择了血清淀粉样蛋白 A（SAA）和α1-酸性糖蛋白（α1-AGP）作为急性子宫炎症的潜在循环标记物进行评估，因为有报道称这两种急性期蛋白的浓度在患有活动性子宫感染的奶牛产后早期会升高。我们从子宫感染诱导模型中采集了血清样本，用于测量这些标记物的浓度。在产后 48 天，通过向子宫注入 107 或 109 cfu 的化脓性真菌（每头奶牛 n = 9；细菌组 n = 18）或生理盐水作为对照（n = 18）来诱导感染。虽然感染刺激了子宫多形核中性粒细胞的增加，但不同输注组血清中的 SAA 和 α1-AGP 浓度并无差异。随后，根据子宫内膜炎的存在情况，将奶牛分为子宫健康组和子宫输液组。与子宫内膜炎阴性-感染阳性（9 头）、子宫内膜炎阳性-感染阴性（5 头）或子宫内膜炎阳性-感染阳性的奶牛相比，子宫内膜炎阴性-感染阴性（11 头）的奶牛的平均 SAA 浓度更高。α1-AGP浓度在子宫健康组之间没有差异。

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引用次数: 0

A comprehensive integration of factors affecting vitamin B12 concentration in milk of Holstein cows: Genetic variability, milk productivity, animal characteristics, and feeding management 全面整合影响荷斯坦奶牛牛奶中维生素 B12 浓度的因素：遗传变异、产奶量、动物特征和饲养管理

JDS communications

Pub Date : 2024-11-01 DOI: 10.3168/jdsc.2023-0535

Mélissa Duplessis , Christiane L. Girard , Doris Pellerin , Liliana Fadul-Pacheco , Roger I. Cue

Daily vitamin B₁₂ (VB₁₂) requirements of humans can naturally be fulfilled by animal product consumption, especially products from ruminants because of bacteria dwelling in their rumen. Indeed, only bacteria can synthesize this vitamin. Milk is hence an excellent source of VB₁₂. This cross-sectional study was undertaken to unravel factors, such as genetic variation, diet and cow characteristics, and milk production, explaining the large variation in milk VB₁₂ concentration among cows by using an integrative approach. Milk samples from 2 consecutive milkings were collected from 3,533 Canadian Holstein cows (1,239 first, 932 second, and 1,362 third and more lactations) located in 99 herds with various feeding management. For the purpose of genetic variation analysis, pedigrees were traced back for 3 complete generations for each sire and dam. A total of 10,021 identities were used in the subsequent genetic analyses. Milk VB₁₂ averaged 4.2 ng/mL with a range between 0.7 and 9.0 ng/mL. Dietary fiber (NDF from forage, dietary NDF, ADF, and lignin) increased and dietary components related to energy (NFC, starch, NE_L, and percentage of concentrate) decreased VB₁₂ in milk. Milk VB₁₂ varied with DIM, with a similar pattern as milk fat and protein concentration lactation curves. Milk VB₁₂ increased as age at calving increased. When disregarding the herd variance, the heritability value was 0.37, meaning that milk VB₁₂ can be modified by genetic selection. The final model including factors related to the diet, animal characteristics and milk productivity, and genetic variation explained 79% (pseudo-R²) of the milk VB₁₂ variation. When excluding the random effect of the cow (i.e., excluding the animal and genetic relationships), the pseudo-R² dropped to 43%, reinforcing the importance of genetic variation in explaining milk VB₁₂ variation. To our knowledge, the present study is the most comprehensive evaluation of factors affecting milk VB₁₂ variation including the greatest number of cows from various lactation stages.

:人类每天所需的维生素 B 12 (VB 12) 自然可以通过食用动物产品，特别是反刍动物的产品来满足，因为反刍动物的瘤胃中含有细菌。事实上，只有细菌才能合成这种维生素。因此，牛奶是 VB 12 的最佳来源。这项横断面研究采用综合方法，旨在揭示造成奶牛之间牛奶 B 12 浓度差异巨大的各种因素，如遗传变异、饮食和奶牛特征以及牛奶产量。研究人员从 3,533 头加拿大荷斯坦奶牛（1,239 头头等奶牛、932 头中等奶牛、2,533 头中等奶牛）中收集了连续两次挤奶的牛奶样本。

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引用次数: 0

Multi-omics analysis elucidates the host-microbiome interplay in severe udder cleft dermatitis lesions in dairy cows 多组学分析阐明奶牛严重乳房裂皮炎病变中宿主与微生物组的相互作用

JDS communications

Pub Date : 2024-11-01 DOI: 10.3168/jdsc.2023-0537

A.S. Vermeersch , F. Van Nieuwerburgh , Y. Gansemans , M. Ali , R. Ducatelle , P. Geldhof , D. Deforce , J. Callens , G. Opsomer

Udder cleft dermatitis is a skin disease in dairy cattle that is characterized by painful, large open wounds between the udder halves or at the front udder attachment. Its impact on animal welfare and production warrants an in-depth investigation of its pathogenesis. The present study delves into the pathophysiology of severe udder cleft dermatitis, employing a multi-omics approach by integrating transcriptomic and metagenomic data obtained from samples of severe udder cleft dermatitis lesions and healthy udder skin of dairy cattle. All dominant features selected from the virulence factor, taxonomic, and transcriptomic datasets, except for the facultative pathogen Streptococcus pyogenes, form a network that could be associated with the healthy udder skin. The severe udder cleft dermatitis–associated Streptococcus pyogenes exhibited a negative correlation with these virulence factors and genes, but was not correlated with the other commensal bacteria in the analysis. Examining the different components interacting with each other could advance our understanding of the pathogenesis of severe udder cleft dermatitis.

乳房裂皮炎是奶牛的一种皮肤病，其特征是在乳房两半之间或乳房前部附着处出现疼痛的大面积开放性伤口。这种疾病对动物福利和生产都有影响，因此有必要对其发病机制进行深入研究。本研究采用多组学方法，通过整合从严重乳房裂皮炎病变和奶牛健康乳房皮肤样本中获得的转录组和元基因组数据，对严重乳房裂皮炎的病理生理学进行了深入研究。除化脓性链球菌外，从毒力因子、分类学和转录组数据集中选取的所有优势特征都形成了一个可能与健康乳房皮肤相关的网络。与严重乳房裂皮炎相关的化脓性链球菌与这些毒力因子和基因呈负相关，但与分析中的其他共生细菌无关。研究不同成分之间的相互作用可加深我们对严重乳房裂皮炎发病机理的了解。

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引用次数: 0

ST8-t008-SCCmec IV methicillin-resistant Staphylococcus aureus in retail fresh cheese 零售新鲜奶酪中的 ST8-t008-SCC IV 型耐甲氧西林金黄色葡萄球菌（MRSA）

JDS communications

Pub Date : 2024-11-01 DOI: 10.3168/jdsc.2023-0521

Carolina Chaves , Melissa Montenegro , Hyrina Piedra , Marta Pérez-Villanueva , César Rodríguez

This study reports the finding of 3 ST8-t008-SCC_mec IVa (2B) methicillin-resistant Staphylococcus aureus (MRSA) strains in fresh cheese purchased within a single market in Costa Rica. In line with the finding of the resistance genes mecA, blaZ, mph(C), and msr(A) in their genomes, these bacteria showed phenotypic resistance to multiple β-lactams and erythromycin. In addition, they carry genes for acquired resistance to aminoglycosides (aph(3′)-III) and fosfomycin (fosD), and genes for a myriad of virulence factors, including adhesins, hemolysins, and exotoxins. Our strains share multiple genomic features with MRSA from the USA300 lineage, which is a widely distributed and highly virulent strain implicated in community infections. As a result, consuming these or similar products could lead to multidrug infections in susceptible individuals. These results highlight safety deficiencies in cheese production practices and emphasize the risk of foodborne transmission of hard-to-treat ST8 MRSA strains.

本研究报告称，在哥斯达黎加一个市场上购买的新鲜奶酪中发现了 3 株 ST8-t008-SCCmec IVa (2B) 耐甲氧西林金黄色葡萄球菌（MRSA）。由于在其基因组中发现了耐药基因 mecA、blaZ、mph(C) 和 msr(A)，这些细菌表现出对多种 β-内酰胺类药物和红霉素的表型耐药性。此外，它们还携带对氨基糖苷类（aph(3′)-III）和磷霉素（fosD）的获得性抗性基因，以及大量毒力因子的基因，包括粘附素、溶血素和外毒素。我们的菌株与美国 300 株系的 MRSA 有多个基因组特征，后者是一种广泛分布的高致病性菌株，与社区感染有牵连。因此，食用这些产品或类似产品可能会导致易感人群感染多种药物。这些结果凸显了奶酪生产实践中的安全缺陷，并强调了难以处理的 ST8 MRSA 菌株通过食物传播的风险。

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引用次数: 0

Evaluation of serum concentrations of total protein and gamma-globulin as an indicator of serum immunoglobulin G concentration in dairy calves 将血清总蛋白和伽马球蛋白浓度作为奶牛血清免疫球蛋白 G 浓度的指标进行评估

JDS communications

Pub Date : 2024-11-01 DOI: 10.3168/jdsc.2023-0469

K. Murayama , N. Kobayashi , N. Nishizawa , M. Oba , T. Sugino

The aim of this study was to evaluate precision of estimating serum IgG concentration from total protein (TP) or gamma-globulin (γGLB) concentration as an alternative approach, and to compare morbidity of preweaning dairy calves differing in serum γGLB concentration. In trial 1, blood was sampled from 129 Holstein calves in the first week after birth, and serum concentrations of TP, γGLB, and IgG were measured. Spearman's correlation coefficient (r_s) between serum IgG and TP concentrations was 0.89, and r_s between serum IgG and γGLB concentrations was 0.96. Absolute residual (observed − predicted) serum IgG concentrations were smaller when estimated by serum γGLB concentration than by serum TP concentration, and differences in the absolute residuals were smaller for calves fed colostrum replacer (1.68 vs. 4.29 g/L) than those fed whole colostrum (2.41 vs. 3.48 g/L). In trial 2, blood was sampled from 740 Holstein heifer calves during the first week of age, and serum γGLB concentration was measured. The calves were divided into 4 categories based on their serum γGLB concentration; ≥1.0 g/dL (excellent), 0.7 ≤ γGLB <1.0 g/dL (good), 0.4 ≤ γGLB <0.7 g/dL (fair), and <0.4 g/dL (poor). Morbidity for diarrhea and respiratory disease in preweaning dairy calves was determined for the first 28 and 56 d of age, and compared among the 4 categories based on serum γGLB concentration. Calves with serum γGLB concentration higher than 0.7 g/dL (good and excellent) had less diarrhea during the first 28 d of age than those with lower serum γGLB concentration (fair and poor). Calves with serum γGLB concentration higher than 1.0 g/dL (excellent) had less respiratory diseases for the first 56 d of age than those with lower serum γGLB concentration (good, fair, and poor). These results suggest that serum IgG concentration can be estimated more precisely from concentration of γGLB than TP particularly for calves fed colostrum replacer, and that γGLB concentrations in the first week of age are associated with morbidity of calves. Transfer of passive immunity in dairy calves can be assessed effectively by serum γGLB concentration.

本研究旨在评估从总蛋白（TP）或γ-球蛋白（γGLB）浓度估算血清IgG浓度的精确度，并比较不同血清γGLB浓度的断奶前乳牛的发病率。在试验 1 中，对 129 头荷斯坦犊牛出生后第一周的血液进行采样，并测量血清中 TP、γGLB 和 IgG 的浓度。血清 IgG 和 TP 浓度之间的 Spearman 相关系数 (rs) 为 0.89，血清 IgG 和 γGLB 浓度之间的 rs 为 0.96。用血清 γGLB 浓度估算的血清 IgG 绝对残差（观察值 - 预测值）小于用血清 TP 浓度估算的血清 IgG 绝对残差（观察值 - 预测值），饲喂牛初乳代用品的犊牛的绝对残差（1.68 克/升 vs. 4.29 克/升）小于饲喂全牛初乳的犊牛（2.41 克/升 vs. 3.48 克/升）。在试验 2 中，对 740 头荷斯坦小母牛在一周龄时进行了血液采样，并测量了血清 γGLB 浓度。根据血清 γGLB 浓度将犊牛分为 4 类：≥1.0 g/dL（优）、0.7 ≤ γGLB <1.0g/dL（良）、0.4 ≤ γGLB <0.7g/dL（中）和 <0.4g/dL（差）。测定断奶前奶牛犊牛头 28 天和 56 天的腹泻和呼吸道疾病发病率，并根据血清 γGLB 浓度对 4 个类别进行比较。与血清γGLB浓度较低（一般和较差）的犊牛相比，血清γGLB浓度高于0.7 g/dL（好和优）的犊牛在头28日龄腹泻较少。血清 γGLB 浓度高于 1.0 g/dL（优）的犊牛与血清 γGLB 浓度较低（良、中、差）的犊牛相比，在犊牛出生后的前 56 d 患呼吸道疾病的情况较少。这些结果表明，根据γGLB的浓度可以比TP更精确地估算血清IgG的浓度，特别是对于饲喂初乳代用品的犊牛，而且γGLB在犊牛出生后第一周的浓度与犊牛的发病率有关。通过血清γGLB浓度可有效评估奶牛犊牛被动免疫的转移。

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引用次数: 0

Inhibitory effect of bovine milk osteopontin on the initial attachment of Streptococcus mutans 牛乳补骨脂素对变异链球菌初始附着的抑制作用

JDS communications

Pub Date : 2024-11-01 DOI: 10.3168/jdsc.2024-0558

Hisako Ishizuka , Kazuna Ishihara , Hideo Yonezawa , Kazuyuki Ishihara , Takashi Muramatsu

We investigated the effect of bovine milk osteopontin (OPN) on the initial adhesion of Streptococcus mutans to hydroxyapatite. Hydroxyapatite pellets were immersed in a 5.4 µM OPN solution at 37°C for 30 min. As a control, Milli-Q water was used. Streptococcus mutans were incubated at 37°C for 2 h on the pellets. Crystal violet staining and the quantitation of DNA were evaluated. Violet staining was observed on the hydroxyapatite pellets in the control group, but faint staining was seen in the OPN group. The amount of DNA attached to the hydroxyapatite pellet was significantly lower in the OPN group. These results suggest that initial adhesion of S. mutans to the hydroxyapatite is inhibited with OPN.

我们研究了牛乳补骨脂素（OPN）对变异链球菌与羟基磷灰石初始粘附的影响。将羟基磷灰石颗粒浸泡在 5.4 µM 的 OPN 溶液中，温度为 37°C，时间为 30 分钟。使用 Milli-Q 水作为对照。变异链球菌在颗粒上 37°C 孵育 2 小时。对水晶紫染色和 DNA 定量进行评估。对照组的羟基磷灰石颗粒上观察到紫色染色，但 OPN 组的染色较淡。在 OPN 组中，附着在羟基磷灰石颗粒上的 DNA 数量明显较少。这些结果表明，OPN 可抑制变异棒状杆菌对羟基磷灰石的初始粘附。

引用次数: 0

Early-life cow-level risk factors for sole ulcers in primiparous dairy cows 初产奶牛鳎目鱼溃疡的早期奶牛风险因素

JDS communications

Pub Date : 2024-11-01 DOI: 10.3168/jdsc.2024-0544

Peter T. Thomsen , Hans Houe

Sole ulcers negatively affect cow welfare and production economy. Previous cases of sole ulcers increase the risk of new or recurrent cases, and prevention of sole ulcers during the first lactation may therefore have a long-term effect, also in later lactations. Until now, risk factors for sole ulcers in the first lactation, associated with the period before heifers calve for the first time, have not been investigated. This study evaluated early-life cow-level risk factors for sole ulcers at the first hoof trimming in the first lactation. Early-life risk factors were defined as risk factors associated with the period before a cow calves for the first time. A dataset including information about all hoof trimming recordings during the years 2020 to 2022, and information about individual cows, was retrieved from the Danish Cattle Database. The dataset included only primiparous cows, and only cows that were hoof trimmed at least once during the first lactation. Overall, 1.95% of 466,113 cows included in the study had sole ulcers at the first hoof trimming in the first lactation. Results from a logistic regression model demonstrated a statistically significant interaction between breed and age at first calving (grouped based on quartiles within breed). Overall, across breeds, odds ratios of sole ulcers at the first hoof trimming in the first lactation were generally approximately 0.5 in the first quartile of age at first calving, approximately 0.6 in the second quartile, and approximately 0.75 in the third quartile, compared with the fourth quartile within the same breed. Odds of sole ulcers were generally higher in Jersey and Danish Red Dairy cows, compared with Holstein. In conclusion, the odds of sole ulcers in the first lactation increased with increasing age at first calving, and was approximately twice as high in cows calving among the oldest 25% within a breed, compared with cows calving among the youngest 25%. Focus on early-life risk factors for sole ulcers may have a major influence on the occurrence of sole ulcers throughout the life of cows.

牛蹄底溃疡对奶牛的福利和生产经济产生负面影响。以前发生过的鳎目鱼溃疡会增加新发或复发的风险，因此在第一泌乳期预防鳎目鱼溃疡可能会对以后的泌乳期产生长期影响。迄今为止，与母牛首次产犊前有关的第一泌乳期足底溃疡风险因素尚未得到研究。本研究评估了第一泌乳期第一次修蹄时发生足底溃疡的母牛早期风险因素。生命早期风险因素被定义为与母牛首次产犊前相关的风险因素。我们从丹麦牛数据库（Danish Cattle Database）中检索了一个数据集，其中包括 2020 年至 2022 年期间所有修蹄记录的信息以及奶牛个体的信息。该数据集仅包括初产奶牛，以及在第一个泌乳期至少修蹄一次的奶牛。总体而言，在纳入研究的 466,113 头奶牛中，有 1.95% 的奶牛在第一个泌乳期第一次修蹄时患有足底溃疡。逻辑回归模型的结果表明，品种与首次产犊年龄之间存在显著的统计学交互作用（根据品种内的四分位数分组）。总体而言，与同一品种中的第四个四分位数相比，不同品种在第一个泌乳期第一次修蹄时发生足底溃疡的几率比一般在初产年龄的第一个四分位数约为 0.5，第二个四分位数约为 0.6，第三个四分位数约为 0.75。与荷斯坦奶牛相比，娟姗牛和丹麦红奶牛发生足底溃疡的几率普遍较高。总之，首次泌乳期发生足底溃疡的几率随着首次产犊年龄的增加而增加，在一个品种中，产犊年龄最大的 25% 的奶牛发生足底溃疡的几率大约是产犊年龄最小的 25% 的奶牛的两倍。关注蹄底溃疡的早期风险因素可能会对奶牛一生中蹄底溃疡的发生产生重大影响。

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引用次数: 0

Evaluation of National Academies of Sciences, Engineering, and Medicine (NASEM, 2021) feed evaluation model on predictions of milk protein yield on Québec commercial dairy farms NASEM 2021 对魁北克商业奶牛场牛奶蛋白产量预测的评估

JDS communications

Pub Date : 2024-11-01 DOI: 10.3168/jdsc.2024-0549

S. Binggeli , H. Lapierre , R. Martineau , D.R. Ouellet , E. Charbonneau , D. Pellerin

A recent study assessed the ability of 4 feed evaluation models to predict milk protein yield (MPY) in a commercial context, with data of 541 cows from 23 dairy herds in the province of Québec, Canada. However, the recently published Nutrient Requirements of Dairy Cattle from the National Academies of Sciences, Engineering, and Medicine (NASEM, 2021) was not released at that time. Thus, the current study evaluated NASEM using the same dataset. To be consistent with the previous study, predicted DMI was used. Therefore, MPY was predicted using the 2 estimations of DMI proposed by NASEM: one based on animal characteristics only (DMI_Ao) and one also including ration characteristics (DMI_A&R). For each type of DMI estimates, 2 MPY predictions were made, using (1) the multivariate equation directly published in NASEM and (2) a variable efficiency of utilization of MP predicted using inputs and outputs from NASEM, published a posteriori. With the 2 approaches, multivariate and variable efficiency, the DMI_A&R yielded the best MPY predictions. The multivariate equation showed a regression bias between observed and predicted MPY with both DMI estimations. The estimated variable efficiency allowed for MPY predictions without mean and regression biases. With DMI_A&R, concordance correlation coefficients (CCC) were 0.72 and 0.78 for MPY predicted using the multivariate and variable efficiency equations, respectively. In comparison, DMI_Ao CCC were 0.60 and 0.71, respectively. In conclusion, on commercial farms, where dairy rations are usually optimized for a group of cows, estimates of DMI based on animal and rations characteristics yielded the best MPY predictions. The multivariate equation from NASEM predicted MPY with a regression bias, whereas the variable efficiency of utilization of MP based on MP and energy supplies resulted in no bias in MPY predictions.

最近的一项研究利用加拿大魁北克省 23 个奶牛场的 541 头奶牛的数据，评估了 4 种饲料评估模型在商业环境中预测牛奶蛋白质产量（MPY）的能力。然而，美国国家科学、工程和医学院（NASEM，2021 年）最近出版的《奶牛营养需求》当时尚未发布。因此，本研究使用相同的数据集对 NASEM 进行了评估。为了与之前的研究保持一致，使用了预测的 DMI。因此，使用 NASEM 提出的两种 DMI 估计值来预测 MPY：一种仅基于动物特征（DMIAo），另一种还包括日粮特征（DMIA&R）。对于每种类型的 DMI 估计值，均使用以下两种方法预测 MPY：(1) NASEM 直接公布的多变量方程；(2) 使用 NASEM 的输入和输出预测的 MP 可变利用效率（事后公布）。通过多变量和可变效率这两种方法，DMIA&R 得出的 MPY 预测结果最好。多变量方程显示，在两个 DMI 估计值中，观测到的 MPY 与预测的 MPY 之间存在回归偏差。估算的变量效率使 MPY 预测没有平均偏差和回归偏差。在 DMIA&R 中，使用多元方程和变量效率方程预测的 MPY 的一致性相关系数 (CCC) 分别为 0.72 和 0.78。相比之下，DMIAo 的 CCC 分别为 0.60 和 0.71。总之，在商业化牧场中，奶牛日粮通常是针对一组奶牛进行优化，根据动物和日粮特征估算的 DMI 预测 MPY 最佳。来自 NASEM 的多元方程对 MPY 的预测存在回归偏差，而基于 MP 和能量供应的 MP 利用效率变量对 MPY 的预测没有偏差。

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